COPT Defense Properties
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COPT Defense Properties - 10-K annual report


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UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 10-K

ANNUAL REPORT PURSUANT TO SECTIONS 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

(Mark one) 

ý

ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2007

or

o

TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from                                    to                                     

Commission file number 1-14023

GRAPHIC

Corporate Office Properties Trust
(Exact name of registrant as specified in its charter)

Maryland
(State or other jurisdiction of incorporation or organization)
 23-2947217
(IRS Employer Identification No.)

6711 Columbia Gateway Drive, Suite 300
Columbia, MD

(Address of principal executive offices)

 

21046
(Zip Code)

Registrant's telephone number, including area code: (443) 285-5400


Securities registered pursuant to Section 12(b) of the Act:

(Title of Each Class)
 (Name of Exchange on Which Registered)
Common Shares of beneficial interest, $0.01 par value New York Stock Exchange
Series G Cumulative Redeemable Preferred Shares of beneficial interest, $0.01 par value New York Stock Exchange
Series H Cumulative Redeemable Preferred Shares of beneficial interest, $0.01 par value New York Stock Exchange
Series J Cumulative Redeemable Preferred Shares of beneficial interest, $0.01 par value New York Stock Exchange

Securities registered pursuant to Section 12(g) of the Act: None

          Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. ý Yes o No

          Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Exchange Act. o Yes ý No

          Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. ý Yes o No

          Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant's knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. o

          Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See definition of "large accelerated filer," "accelerated filer" and "smaller reporting company" in Rule 12b-2 of the Exchange Act. (Check One):

Large accelerated filer ý Accelerated filer o Non-accelerated filer o
(Do not check if a smaller
reporting company)
 Smaller reporting company o

          Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act.) o Yes ý No

          The aggregate market value of the voting and nonvoting common equity held by non-affiliates of the registrant was approximately $1.9 billion, as calculated using the closing price of the common shares of beneficial interest on the New York Stock Exchange and our outstanding shares as of June 29, 2007; for purposes of calculating this amount only, affiliates are defined as Trustees, executive owners and beneficial owners of more than 10% of the registrant's outstanding common shares of beneficial interest. At January 31, 2008, 47,383,967 of the registrant's common shares of beneficial interest, $0.01 par value, were outstanding.

          Portions of the annual shareholder report for the year ended December 31, 2007 are incorporated by reference into Parts I and II of this Form 10-K and portions of the proxy statement of the registrant for its 2008 Annual Meeting of Shareholders to be filed within 120 days after the end of the fiscal year covered by this Form 10-K are incorporated by reference into Part III of this Form 10-K.





Table of Contents

Form 10-K

 
  
  
PART I    
 
ITEM 1.

 

BUSINESS

 

4
 ITEM 1A. RISK FACTORS 10
 ITEM 1B. UNRESOLVED STAFF COMMENTS 19
 ITEM 2. PROPERTIES 20
 ITEM 3. LEGAL PROCEEDINGS 34
 ITEM 4. SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS 35

PART II

 

 

 

 
 
ITEM 5.

 

MARKET FOR REGISTRANT'S COMMON EQUITY, RELATED STOCKHOLDER MATTERS AND ISSUER PURCHASES OF EQUITY SECURITIES

 

35
 ITEM 6. SELECTED FINANCIAL DATA 37
 ITEM 7. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS 39
 ITEM 7A. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK 72
 ITEM 8. FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA 73
 ITEM 9. CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND FINANCIAL DISCLOSURE 73
 ITEM 9A. CONTROLS AND PROCEDURES 73
 ITEM 9B. OTHER INFORMATION 74

PART III

 

 

 

 
 
ITEM 10.

 

DIRECTORS, EXECUTIVE OFFICERS AND CORPORATE GOVERNANCE

 

74
 ITEM 11. EXECUTIVE COMPENSATION 74
 ITEM 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT AND RELATED STOCKHOLDER MATTERS 74
 ITEM 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS, AND DIRECTOR INDEPENDENCE 74
 ITEM 14. PRINCIPAL ACCOUNTANT FEES AND SERVICES 74

PART IV

 

 

 

 
 
ITEM 15.

 

EXHIBITS AND FINANCIAL STATEMENT SCHEDULES

 

74

2



FORWARD-LOOKING STATEMENTS

        This Form 10-K contains "forward-looking" statements, as defined in the Private Securities Litigation Reform Act of 1995, that are based on our current expectations, estimates and projections about future events and financial trends affecting the financial condition and operations of our business. Forward-looking statements can be identified by the use of words such as "may," "will," "should," "expect," "estimate" or other comparable terminology. Forward-looking statements are inherently subject to risks and uncertainties, many of which we cannot predict with accuracy and some of which we might not even anticipate. Although we believe that the expectations, estimates and projections reflected in such forward-looking statements are based on reasonable assumptions at the time made, we can give no assurance that these expectations, estimates and projections will be achieved. Future events and actual results may differ materially from those discussed in the forward-looking statements. Important factors that may affect these expectations, estimates and projections include, but are not limited to:

    our ability to borrow on favorable terms;

    general economic and business conditions, which will, among other things, affect office property demand and rents, tenant creditworthiness, interest rates and financing availability;

    adverse changes in the real estate markets including, among other things, increased competition with other companies;

    risks of real estate acquisition and development activities, including, among other things, risks that development projects may not be completed on schedule, that tenants may not take occupancy or pay rent or that development and operating costs may be greater than anticipated;

    risks of investing through joint venture structures, including risks that our joint venture partners may not fulfill their financial obligations as investors or may take actions that are inconsistent with our objectives;

    our ability to satisfy and operate effectively under Federal income tax rules relating to real estate investment trusts and partnerships;

    governmental actions and initiatives; and

    environmental requirements.

        For further information on factors that could affect the company and the statements contained herein, you should refer to the section below entitled "Item 1A. Risk Factors." We undertake no obligation to update or supplement forward-looking statements.

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PART I

Item 1.    Business

OUR COMPANY

        General.    We are a fully-integrated and self-managed real estate investment trust ("REIT") that focuses on the acquisition, development, ownership, management and leasing of suburban office properties in select markets and submarkets. We also focus on servicing the multi-location requirements of strategic customers and strategic industries in which tenants have specialized product requirements. Our properties are typically concentrated in large office parks located in demographically strong markets and submarkets and/or near demand drivers for strategic customers and industries. As of December 31, 2007, our investments in real estate included the following:

    228 wholly owned operating properties in Maryland, Virginia, Colorado, Texas, Pennsylvania and New Jersey containing 17.8 million rentable square feet that were 92.6% occupied;

    19 wholly owned office properties under construction or development that we estimate will total approximately 1.8 million square feet upon completion and one wholly owned office property totaling 74,749 square feet that was under redevelopment;

    wholly owned land parcels totaling 1,479 acres that were predominantly located near certain of our operating properties and that we believe are potentially developable into approximately 12.4 million square feet; and

    partial ownership interests through joint ventures in the following:

    18 operating properties containing approximately 805,796 rentable square feet that were 90.4% occupied;

    one property under construction that we estimate will total 151,800 square feet upon completion and an aggregate of 471,866 square feet in three properties that were under redevelopment; and

    land parcels totaling 225 acres (including 56 acres under contract) that were predominantly located near certain of our operating properties and potentially developable into approximately 2.5 million square feet.

        We conduct almost all of our operations through our operating partnership, Corporate Office Properties, L.P. (the "Operating Partnership"), a Delaware limited partnership, of which we are the managing general partner. The Operating Partnership owns real estate both directly and through subsidiary partnerships and limited liability companies ("LLCs"). The Operating Partnership also owns 100% of Corporate Office Management, Inc. ("COMI") and owns, either directly or through COMI, 100% of the following entities that provide real estate services primarily to us but also to third parties (collectively defined as the "Service Companies"): COPT Property Management Services, LLC ("CPM"), COPT Development & Construction Services, LLC ("CDC"), Corporate Development Services, LLC ("CDS") and COPT Environmental Systems, LLC ("CES").

        Interests in our Operating Partnership are in the form of common and preferred units. As of December 31, 2007, we owned approximately 84.7% of the outstanding common units and approximately 95.8% of the outstanding preferred units in our Operating Partnership. The remaining common and preferred units in our Operating Partnership were owned by third parties, which included certain of our Trustees.

        We believe that we are organized and have operated in a manner that permits us to satisfy the requirements for taxation as a REIT under the Internal Revenue Code of 1986, as amended, and we

4



intend to continue to operate in such a manner. If we qualify for taxation as a REIT, we generally will not be subject to Federal income tax on our taxable income that is distributed to our shareholders. A REIT is subject to a number of organizational and operational requirements, including a requirement that it distribute to its shareholders at least 90% of its annual taxable income (excluding net capital gains).

        Our executive offices are located at 6711 Columbia Gateway Drive, Suite 300, Columbia, Maryland 21046 and our telephone number is (443) 285-5400.

        Corporate Office Properties Trust's Internet address is www.copt.com. We make available on our Internet website free of charge our annual report on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K and amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) of the Exchange Act as soon as reasonably possible after we file such material with the Securities and Exchange Commission. In addition, we have made available on our Internet website under the heading "Corporate Governance" the charters for our Board of Trustees' Audit Committee, Nominating and Corporate Governance Committee and Compensation Committee, as well as our Corporate Governance Guidelines, Code of Business Conduct and Ethics and Code of Ethics for Financial Officers. We intend to make available on our website any future amendments or waivers to our Code of Business Conduct and Ethics and Code of Ethics for Financial Officers within four business days after any such amendments or waivers. The information on our Internet site is not part of this report.

        The Securities and Exchange Commission (the "SEC") maintains an Internet website that contains reports, proxy and information statements and other information regarding issuers that file electronically with the SEC. This Internet website can be accessed at www.sec.gov. The public may also read and copy paper filings that we have made with the SEC at the SEC's Public Reference Room. Information on the operation of the Public Reference Room may be obtained by calling (800) SEC-0330.

Significant 2007 Developments

        During 2007, we:

    experienced increased revenues, operating expenses and operating income due primarily to the addition of properties through acquisition and construction activities;

    finished the period with 92.6% occupancy of our wholly owned portfolio of properties;

    completed, on January 9 and 10, 2007, a series of transactions that resulted in the acquisition of 56 operating properties totaling approximately 2.4 million square feet and land parcels totaling 187 acres. We refer to these transactions collectively as the Nottingham Acquisition. All of the acquired properties are located in Maryland, with 36 of the operating properties, totaling 1.6 million square feet, and land parcels totaling 175 acres, located in White Marsh, Maryland (located in the Suburban Baltimore region) and the remaining properties and land parcels located in other regions in Northern Baltimore County and the Baltimore/Washington Corridor. We believe that the land parcels can support at least 2.0 million developable square feet. We completed the Nottingham Acquisition for an aggregate cost of $366.9 million. We financed the acquisition by issuing $26.6 million in Series K Cumulative Redeemable Convertible Preferred Shares of beneficial interest (the "Series K Preferred Shares") to the seller at a value of, and liquidation preference equal to, $50 per share, issuing $156.7 million in common shares of beneficial interest ("common shares") to the seller at a value of $49.57 per share, using $20.1 million from an escrow funded by proceeds from one of our property sales and using debt borrowings for the remainder;

5


      had five newly-constructed properties totaling 568,433 square feet become fully operational (68,196 of these square feet were placed into service in 2006). We also had 48,377 square feet placed into service in one partially operational property;

      sold four operating properties (including one acquired in the Nottingham Acquisition) and three parcels of land acquired in the Nottingham Acquisition for a total of $26.5 million, resulting in recognized gains before minority interest and taxes of $6.9 million (we incurred $1.1 million in income tax expense on these sales).

      amended and restated the credit agreement on our Revolving Credit Facility on October 1, 2007, increasing the amount of the lenders' aggregate commitment under the facility from $500.0 million to $600.0 million with a right for us to further increase the lenders' aggregate commitment during the term to a maximum of $800.0 million, subject to certain conditions. The facility matures on September 30, 2011, and may be extended by us for a period of one year, subject to certain conditions; and

      borrowed $150.0 million under a mortgage loan with a 10-year term at a fixed rate of 5.65%, using the proceeds to repay other debt.

    Subsequent Events

            Subsequent to December 31, 2007, we:

      completed the formation of M Square Associates, LLC, a consolidated joint venture in which we hold a 45% equity interest, on January 29, 2008. This joint venture will own, develop and manage office properties, approved for up to approximately 750,000 square feet, located in M Square Research Park in College Park, Maryland (College Park, Maryland is located in the Suburban Maryland region). This joint venture had construction underway on a 118,107 square foot property within M Square Research Park;

      had a 59,763 square foot property in Colorado Springs that was 100% pre-leased become fully operational on January 29, 2008; and

      completed the sale of the 429 Ridge Road property in the Northern/Central New Jersey region for $17.0 million on January 31, 2008.

    Corporate Objectives and Strategies

            Our primary objectives are to achieve sustainable long-term growth in results of operations and to maximize long-term shareholder value. Important elements of our strategy are set forth below:

            Market Strategy.    We typically concentrate our operations in markets and submarkets where we believe that we already possess or can achieve the critical mass necessary to maximize management efficiencies, operating synergies and competitive advantages through our acquisition, property management, leasing and development programs. The attributes we look for in selecting markets and submarkets include, among others: (1) proximity to large demand drivers; (2) strong demographics; (3) attractiveness to high quality tenants, including strategic customers and strategic industries; (4) potential for growth and stability in economic down cycles; and (5) future acquisition and development opportunities. When we select a market or submarket, our strategy generally involves establishing an initial presence by acquiring properties in that market or submarket and then increasing our ownership through future acquisitions and development. We typically focus on owning and operating properties in business parks located outside of central business districts. We believe that such parks generally attract long-term, high-quality tenants seeking to attract and retain quality work forces

    6



    because they are typically situated along major transportation routes with easy access to support services, amenities and residential communities.

            Customer Strategy.    We focus on establishing, maintaining and expanding strategic customer relationships in multiple locations with tenants that are large, financially sound entities with significant long-term space requirements. We believe that we differentiate ourselves from our competitors through our commitment to outstanding customer service, trust and integrity. We believe that this strategy enables us to establish long-term relationships with quality tenants and enhances our ability to become the landlord of choice in our targeted markets. To enhance the stability of our cash flow, we typically structure our leases with terms ranging from three to ten years. Given the terms of our leases, we monitor the timing of our lease maturities with the goal being that such timing should not be highly concentrated in any given one-year or five-year period.

            Industry Strategy.    As an outgrowth of our customer strategy, we also focus on strategic industries in which tenants have specialized product requirements. For example, a high concentration of our revenues is generated from tenants in the United States defense industry (comprised of the United States Government and defense contractors), predominantly in defense information technology. These tenants are particularly interested in a number of our property submarkets that are located near government installations. We also enable these tenants to benefit from our significant experience in constructing and operating secure properties and properties that meet the United States Government's Force Protection requirements. We believe that this experience coupled with our existing relationships in the United States defense industry position us well to continue and grow in this industry. We seek to reinforce and expand our relationships with current and prospective tenants in this industry, while monitoring our levels of concentration from a business risk perspective.

            Tenant Service Strategy.    Another outgrowth of our customer service strategy is our tenant service strategy, in which we seek to capitalize on our geographic focus and critical mass of properties in our core regions by providing high level, comprehensive services to our tenants. We conduct most of our tenant services activities through our subsidiary service companies. We believe that providing quality services is an integral part of our goal to achieve consistently high levels of tenant satisfaction and retention and, again, position ourselves as a landlord of choice.

            Acquisition Strategies.    We pursue the acquisition of suburban office properties through a three-part acquisition strategy. This strategy includes targeting: (1) entity acquisitions of significant portfolios along with their management to establish prominent ownership positions in new neighboring regions and enhance our management infrastructure; (2) portfolio purchases to enhance our existing submarket positions as well as enter selective new neighboring regions; and (3) opportunistic acquisitions of individual properties in our existing regions. We also pursue acquisition opportunities for properties that meet the multi-location requirements of our strategic customers and strategic industries. We typically seek to make acquisitions at attractive yields and below replacement cost. We also often seek to increase cash flow and enhance the underlying value of acquisitions through repositioning the properties and capitalizing on existing below market leases and expansion opportunities.

            Property Development Strategies.    We balance our acquisition program through selective development and expansion of suburban office properties as market conditions and leasing opportunities support favorable risk-adjusted returns. We generally develop sites that are located near our existing properties. We believe that developing such sites enhances our ability to effectively meet tenant needs and efficiently provide critical tenant services. We also develop sites acquired in other locations in order to meet the multi-location requirements of our strategic customers and strategic industries.

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            Internal Growth Strategies.    We aggressively manage our portfolio to maximize the operating performance of each property through: (1) proactive property management and leasing; (2) achieving operating efficiencies through increasing economies of scale and, where possible, aggregating vendor contracts to achieve volume pricing discounts; (3) renewing tenant leases and re-tenanting at increased rents where market conditions permit; and (4) expanding our tenant and real estate service capabilities.

    Financing Policy

            Our financing policy is aimed at maintaining a flexible capital structure in order to facilitate consistent growth and performance in the face of differing market conditions in the most cost-effective manner. Key components of our policy are set forth below:

      monitoring levels of debt relative to our overall capital structure;

      monitoring the relationship of certain measures of earnings to certain financing cost requirements; these relationships are known as coverage ratios. One coverage ratio on which our financing policy focuses is our fixed charge coverage ratio (defined as various measures of results of operations divided by the sum of (1) interest expense on continuing and discontinued operations; (2) dividends on preferred shares; and (3) distributions on preferred units in our Operating Partnership not owned by us). Coverage ratios such as the fixed charge coverage ratio are important to us in evaluating whether our operations are sufficient to satisfy the cash flow requirements of our debt and equity holders, including minority interest holders;

      monitoring the relationship of our total variable-rate debt to our total debt; this is important to us in limiting the amount of our debt that is subject to future increases in interest rates;

      monitoring the timing of our debt maturities to ensure that the maximum maturities of debt in any year, both including and excluding our primary Revolving Credit Facility, do not exceed a defined percentage of total debt;

      pursuing opportunities to reduce financing costs by refinancing existing debt or redeeming existing preferred equity when we believe market conditions to be favorable;

      pursuing the issuance of common and preferred shares when we believe market conditions to be favorable;

      using units in our Operating Partnership as an equity source to finance our investing activities; this strategy provides prospective property sellers the ability to defer taxable gains by receiving our partnership units in lieu of cash and reduces the need for us to access the equity and debt markets; and

      reducing our equity investment requirements in certain properties through the use of joint venture structures.

    Debt

            For information relating to future maturities of our debt, you should refer to the sections of this report entitled "Management's Discussion and Analysis of Financial Condition and Results of Operations" and "Quantitative and Qualitative Disclosures about Market Risk," as well as Note 9 to our Consolidated Financial Statements and notes thereto, which is located in a separate section at the end of this report beginning on page F-1.

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    Industry Segments

            We operate in one primary industry: suburban office real estate. At December 31, 2007, our suburban office real estate operations had nine primary geographical segments, as set forth below:

      Baltimore/Washington Corridor (generally defined as the Maryland counties of Howard and Anne Arundel);

      Northern Virginia (defined as Fairfax County, Virginia);

      Suburban Maryland (defined as the Maryland counties of Montgomery, Prince George's and Frederick);

      St. Mary's & King George Counties (located in Maryland and Virginia, respectively);

      Suburban Baltimore, Maryland (generally defined as the Maryland counties of Baltimore and Harford)("Suburban Baltimore");

      Colorado Springs, Colorado ("Colorado Springs");

      San Antonio, Texas ("San Antonio");

      Greater Philadelphia, Pennsylvania ("Greater Philadelphia"); and

      Northern/Central New Jersey (as of December 31, 2007, all of our properties in this segment were located in Central New Jersey).

            As of December 31, 2007, 138 of our wholly owned properties were located in what is widely known as the Greater Washington, D.C. region, which includes the first four regions set forth above, and 64 were located in neighboring Suburban Baltimore. At December 31, 2007, we also owned 13 wholly owned properties in Colorado Springs and two in San Antonio. In addition, we owned eight properties in total as of December 31, 2007 in the last two locations set forth above that are considered non-core to the Company. For information relating to these geographic segments, you should refer to Note 16 to our Consolidated Financial Statements, which is included in a separate section at the end of this report beginning on page F-1.

    Employees

            As of December 31, 2007, we had 351 employees. We believe that our relations with our employees are good.

    Competition

            The commercial real estate market is highly competitive. Numerous commercial properties compete with our properties for tenants. Some of the properties competing with ours may be newer or have more desirable locations, or the competing properties' owners may be willing to accept lower rents than are acceptable to us. In addition, the competitive environment for leasing is affected considerably by a number of factors including, among other things, changes in economic factors and supply and demand of space. These factors may make it difficult for us to lease existing vacant space and space associated with future lease expirations at rental rates that are sufficient to meeting our short-term capital needs.

            We also compete for the purchase of commercial property with many entities, including other publicly-traded commercial REITs. Many of our competitors have substantially greater financial resources than ours. In addition, our competitors may be willing to accept lower returns on their

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    investments. If our competitors prevent us from buying properties that we have targeted for acquisition, we may not be able to meet our property acquisition goals.

    Item 1A.    Risk Factors

            Set forth below are risks and uncertainties relating to our business and the ownership of our securities. You should carefully consider each of the risks and uncertainties below and all of the information in this Form 10-K and its Exhibits, including our Consolidated Financial Statements and notes thereto for the year ended December 31, 2007, which are included in a separate section at the end of this report beginning on page F-1.

            We may suffer adverse consequences as a result of our reliance on rental revenues for our income. We earn revenue from renting our properties. Our operating costs do not necessarily fluctuate in relation to changes in our rental revenue. This means that our costs will not necessarily decline and may increase even if our revenues decline.

            For new tenants or upon lease expiration for existing tenants, we generally must make improvements and pay other tenant-related costs for which we may not receive increased rents. We also make building-related capital improvements for which tenants may not reimburse us.

            If our properties do not generate revenue sufficient to meeting our operating expenses and capital costs, we may have to borrow additional amounts to cover these costs. In such circumstances, we would likely have lower profits or possibly incur losses. We may also find in such circumstances that we are unable to borrow to cover such costs, in which case our operations could be adversely affected. Moreover, there may be less or no cash available for distributions to our shareholders.

            In addition, the competitive environment for leasing is affected considerably by a number of factors including, among other things, changes due to economic factors and supply and demand of space. These factors may make it difficult for us to lease existing vacant space and space associated with future lease expirations at rental rates that are sufficient to meeting our short-term capital needs.

            Adverse developments concerning some of our major tenants and industry concentrations could have a negative impact on our revenue. As of December 31, 2007, 20 tenants accounted for 54.8% of the total annualized rental revenue of our wholly owned properties, excluding owner-occupied leasing activity, and our five largest of these tenants accounted for 35.0% of that total. We computed the annualized rental revenue by multiplying by 12 the sum of monthly contractual base rents and estimated monthly expense reimbursements under active leases in our portfolio of wholly owned properties as of December 31, 2007. We consider annualized rental revenue to be a useful measure for analyzing revenue sources because, since it is point-in-time based, it does not contain increases and decreases in revenue associated with periods in which lease terms were not in effect; historical revenue under GAAP does contain such fluctuations. We find the measure particularly useful for leasing, tenant, segment and industry analysis. Information regarding our five largest tenants is set forth below:

    Tenant
     Annualized
    Rental Revenue at
    December 31, 2007

     Percentage of
    Total Annualized
    Rental Revenue of
    Wholly Owned Properties

     Number
    of Leases

     
     (in thousands)
      
      
    United States of America $57,395 16.3%62
    Northrop Grumman Corporation(1)  26,199 7.4%17
    Booz Allen Hamilton, Inc.   19,568 5.5%8
    Computer Sciences Corporation(1)  11,446 3.2%4
    Unisys Corporation  8,843 2.5%4

    (1)
    Includes affiliated organizations and agencies and predecessor companies.

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            If any of our five largest tenants fail to make rental payments to us or if the United States Government elects to terminate several of its leases and the space cannot be re-leased on satisfactory terms, there would be an adverse effect on our financial performance and ability to make distributions to our shareholders.

            As of December 31, 2007, the United States defense industry (comprising the United States Government and defense contractors) accounted for approximately 47.9% of the total annualized rental revenue of our wholly owned properties. Most of the 16.3% of our total annualized rental revenue that we derived from leases with agencies of the United States Government as of December 31, 2007 is included in the 47.9% of our total annualized revenue from the United States defense industry. We classify the revenue from our leases into industry groupings based solely on management's knowledge of the tenants' operations in leased space. Occasionally, classifications require subjective and complex judgments. For example, we have a tenant that is considered by many to be in the computer industry; however, since the nature of that tenant's operations in the space leased from us is focused on providing service to the United States Government's defense department, we classify the revenue we earn from the lease as United States defense industry revenue. We do not use independent sources such as Standard Industrial Classification codes for classifying our revenue into industry groupings and if we did, the resulting groupings would be materially different.

            We have become increasingly reliant on defense industry tenants in recent years due primarily to: (1) increased activity in that industry following the events of September 11, 2001; (2) the strong presence of the industry in a number of our submarkets; and (3) our strategy to form strategic alliances with tenants in that industry. The percentage of our total annualized rental revenue derived from the defense industry could continue to increase. A reduction in government spending for defense could affect the ability of these tenants to fulfill lease obligations or decrease the likelihood that these tenants will renew their leases. In the case of the United States Government, a reduction in government spending could result in the early termination of leases. Such occurrences could have an adverse effect on our results of operations, financial condition, cash flows and ability to make distributions to our shareholders.

            We rely on the ability of our tenants to pay rent and would be harmed by their inability to do so. Our performance depends on the ability of our tenants to fulfill their lease obligations by paying their rental payments in a timely manner. In addition, as noted above, we rely on a few major tenants for a large percentage of our total rental revenue. If one of our major tenants, or a number of our smaller tenants, were to experience financial difficulties, including bankruptcy, insolvency or general downturn of business, there could be an adverse effect on our financial performance and ability to make expected distributions to shareholders.

            Most of our properties are geographically concentrated in the Mid-Atlantic region, particularly in the Greater Washington, D.C. region and neighboring Suburban Baltimore, or in particular office parks. We may suffer economic harm in the event of a decline in the real estate market or general economic conditions in those regions. Most of our properties are located in the Mid-Atlantic region of the United States and, as of December 31, 2007, our properties located in the Greater Washington, D.C. region and neighboring Suburban Baltimore accounted for a combined 87.5% of our total annualized rental revenue from wholly owned properties. Our properties are also typically concentrated in office parks in which we own most of the properties. Consequently, we do not have a broad geographic distribution of our properties. As a result, a decline in the real estate market or general economic conditions in the Mid-Atlantic region, the Greater Washington, D.C. region or the office parks in which our properties are located could have an adverse effect on our financial position, results of operations, cash flows and ability to make expected distributions to our shareholders.

    11


            We would suffer economic harm if we were unable to renew our leases on favorable terms.    When leases expire for our properties, our tenants may not renew or may renew on terms less favorable to us than the terms of their original leases. If a tenant vacates a property, we can expect to experience a vacancy for some period of time, as well as higher capital costs than if a tenant renews. As a result, our financial performance and ability to make expected distributions to our shareholders could be adversely affected if we experience a high volume of tenant departures at the end of their lease terms. Set forth below are the percentages of total annualized rental revenue from wholly owned properties as of December 31, 2007 that are subject to scheduled lease expirations in each of the next five years:

    2008 11.2%
    2009 14.3%
    2010 13.3%
    2011 8.7%
    2012 14.7%

            Most of the leases with our largest tenant, the United States Government, which account for 16.3% of our total annualized rental revenue in wholly owned properties at December 31, 2007, provide for consecutive one-year terms or provide for early termination rights. All of the leasing statistics set forth above assume that the United States Government will remain in the space that it leases through the end of the respective arrangements, without ending consecutive one-year leases prematurely or exercising early termination rights. We report the statistics in this manner since we manage our leasing activities using these same assumptions and believe these assumptions to be probable.

            We may not be able to compete successfully with other entities that operate in our industry.    The commercial real estate market is highly competitive. We compete for the purchase of commercial property with many entities, including other publicly traded commercial REITs. Many of our competitors have substantially greater financial resources than we do. If our competitors prevent us from buying properties that we target for acquisition, we may not be able to meet our property acquisition and development goals. Moreover, numerous commercial properties compete for tenants with our properties. Some of the properties competing with ours may have newer or more desirable locations, or the competing properties' owners may be willing to accept lower rates than are acceptable to us. Competition for property acquisitions, or for tenants in properties that we own, could have an adverse effect on our financial performance and distributions to our shareholders.

            We may be unable to successfully execute our plans to acquire existing commercial real estate properties.    We intend to acquire existing commercial real estate properties to the extent that suitable acquisitions can be made on advantageous terms. Acquisitions of commercial properties entail risks, such as the risks that we may not be in a position, or have the opportunity in the future, to make suitable property acquisitions on advantageous terms and that such acquisitions will fail to perform as expected. The failure of our acquisitions to perform as expected could adversely affect our financial performance and our ability to make distributions to our shareholders.

            We may suffer economic harm as a result of making unsuccessful acquisitions in new markets.    We expect to pursue selective acquisitions of properties in regions where we have not previously owned properties. These acquisitions may entail risks in addition to those we face in other acquisitions where we are familiar with the regions, such as the risk that we do not correctly anticipate conditions or trends in a new region and are therefore not able to operate the acquired property profitably. If this occurs, it could adversely affect our financial performance and our ability to make distributions to our shareholders.

            We may be unable to execute our plans to develop and construct additional properties.    Although the majority of our investments are in currently leased properties, we also develop, construct and

    12



    renovate properties, including some that are not fully pre-leased. When we develop, construct and renovate properties, we assume the risk that actual costs will exceed our budgets, that we will experience delays and that projected leasing will not occur, any of which could adversely affect our financial performance and our ability to make distributions to our shareholders. In addition, we generally do not obtain construction financing commitments until the development stage of a project is complete and construction is about to commence. We may find that we are unable to obtain financing needed to continue with the construction activities for such projects.

            Certain of our properties containing data centers contain space not suitable for lease other than as data centers, which could make it difficult to reposition them for alternative use.    Certain of our properties contain data center space, which is highly specialized space containing extensive electrical and mechanical systems that are designed uniquely to run and maintain banks of computer servers. As a result, in the event we needed to reposition such data center space to being office or industrial rental space, major renovations and expenditures would be required in order for us to prepare the space for re-lease or for us to sell to a buyer for use other than as data center space.

            We may suffer economic harm as a result of the actions of our joint venture partners.    We invest in certain entities in which we are not the exclusive investor or principal decision maker. As of December 31, 2007, we owned 17 fully operational properties and four properties under construction or redevelopment, and control land for future development, through joint ventures. We also continue to pursue new investments in real estate through joint ventures. Aside from our inability to unilaterally control the operations of joint ventures, our investments in joint ventures entail the additional risks that (1) the other parties to these investments may not fulfill their financial obligations as investors, in which case we may need to fund such parties' share of additional capital requirements and (2) the other parties to these investments may take actions that are inconsistent with our objectives, either of which could have an adverse effect on our financial condition, results of operations, cash flows and ability to make expected distributions to our shareholders.

            We are subject to possible environmental liabilities.    We are subject to various Federal, state and local environmental laws. These laws can impose liability on property owners or operators for the costs of removal or remediation of hazardous substances released on a property, even if the property owner was not responsible for the release of the hazardous substances. Costs resulting from environmental liability could be substantial. The presence of hazardous substances on our properties may also adversely affect occupancy and our ability to sell or borrow against those properties. In addition to the costs of government claims under environmental laws, private plaintiffs may bring claims for personal injury or other reasons. Additionally, various laws impose liability for the costs of removal or remediation of hazardous substances at the disposal or treatment facility. Anyone who arranges for the disposal or treatment of hazardous substances at such a facility is potentially liable under such laws. These laws often impose liability on an entity even if the facility was not owned or operated by the entity.

            Real estate investments are illiquid, and we may not be able to sell our properties on a timely basis when we determine it is appropriate to do so.    Real estate investments can be difficult to sell and convert to cash quickly, especially if market conditions are depressed. Such illiquidity will tend to limit our ability to vary our portfolio of properties promptly in response to changes in economic or other conditions. Moreover, under certain circumstances, the Internal Revenue Code imposes certain penalties on a REIT that sells property held for less than four years. In addition, for certain of our properties that we acquired by issuing units in our Operating Partnership, we are restricted by agreements with the sellers of the properties for a certain period of time from entering into transactions (such as the sale or refinancing of the acquired property) that will result in a taxable gain to the sellers without the seller's consent. Due to all of these factors, we may be unable to sell a property at an advantageous time.

    13


            We are subject to other possible liabilities that would adversely affect our financial position and cash flows.    Our properties may be subject to other risks related to current or future laws, including laws benefiting disabled persons, and state or local laws relating to zoning, construction and other matters. These laws may require significant property modifications in the future for which we may not have budgeted and could result in the levy of fines against us. In addition, although we believe that we adequately insure our properties, we are subject to the risk that our insurance may not cover all of the costs to restore a property that is damaged by a fire or other catastrophic events, including acts of war or terrorism. The occurrence of any of these events could have an adverse effect on our financial condition, results of operations, cash flows and ability to make expected distributions to our shareholders.

            We may be subject to increased costs of insurance and limitations on coverage regarding acts of terrorism.    Our portfolio of properties is insured for losses under our property, casualty and umbrella insurance policies through September 30, 2008. These policies include coverage for acts of terrorism. Future changes in the insurance industry's risk assessment approach and pricing structure may increase the cost of insuring our properties and decrease the scope of insurance coverage, either of which could adversely affect our financial position and operating results.

            We may suffer adverse effects as a result of the indebtedness that we carry and the terms and covenants that relate to this debt.    We have in the past operated with slightly higher debt levels than other REITs. Operating with higher debt levels could make it difficult to obtain additional financing when required and could also make us more vulnerable to an economic downturn. The majority of our properties are either collateralized or identified by us to support repayment on indebtedness. In addition, we rely on borrowings to fund some or all of the costs of new property acquisitions, construction and development activities and other items. Our organizational documents do not limit the amount of indebtedness that we may incur. As of December 31, 2007, our total outstanding debt was $1.8 billion and our debt to total assets (defined as (1) the sum of mortgage and other loans and exchangeable senior notes divided by (2) total assets) was 62.3%.

            Payments of principal and interest on our debt may leave us with insufficient cash to operate our properties or pay distributions to our shareholders required to maintain our qualification as a REIT. We are also subject to the risks that:

      we may not be able to refinance our existing indebtedness or refinance on terms as favorable as the terms of our existing indebtedness;

      under the terms of our Revolving Credit Facility, in the event of a default on its terms by us, that our Operating Partnership could be restricted from making cash distributions to us, which could result in reduced distributions to our shareholders or the need for us to incur additional debt to fund these distributions; and

      if we are unable to pay our debt service on time or are unable to comply with restrictive financial covenants in certain of our debt, our lenders could foreclose on our properties securing such debt and, in some cases, other properties and assets that we own.

            Some of our debt is secured by not just one property but, rather, a group of properties. Some of our debt is cross-defaulted, which means that failure to pay interest or principal on a loan above a threshold value will create a default on certain of our other loans. In addition, some of our debt that is cross-defaulted also contains cross-collateralization provisions. Any foreclosure of our properties would result in loss of income and asset value that would negatively affect our financial condition, results of operations, cash flows and ability to make expected distributions to our shareholders. In addition, in certain circumstances, if we are in default and the value of the properties securing a loan is less than the loan balance, we may be required to pay the resulting shortfall to the lender using other assets.

    14


            As of December 31, 2007, 19.1% of our total debt had variable interest rates, including the effect of interest rate swaps. If short-term interest rates were to rise, our debt service payments on adjustable rate debt would increase, which would lower our net income and could decrease our distributions to our shareholders. We use interest rate swap agreements from time to time to reduce the impact of changes in interest rates. Decreases in interest rates would result in increased interest payments due under interest rate swap agreements in place and, in the event we decided to unwind such agreements, could result in us recognizing a loss and remitting a payment.

            We must refinance our debt in the future. As of December 31, 2007, our scheduled debt payments over the next five years, including maturities, were as follows:

    Year

     Amount(1)
     
     
     (in thousands)

     
    2008 $297,120(2)
    2009  62,643 
    2010  74,033 
    2011  470,814(3)
    2012  42,200 

        (1)
        Represents principal maturities only and therefore excludes premiums and discounts.

        (2)
        Includes maturities totaling $84.6 million that may be extended for a one-year period, subject to certain conditions, although we only expect to extend $40.6 million of this amount.

        (3)
        Includes maturities totaling $361.0 million that may be extended for a one-year period, subject to certain conditions.

            Our operations likely will not generate enough cash flow to repay some or all of this debt without additional borrowings or new equity issuances. If we cannot refinance our debt, extend the repayment dates, or raise additional equity prior to the date when our debt matures, we would default on our existing debt, which would have an adverse effect on our financial position, results of operations, cash flows and ability to make expected distributions to our shareholders.

            We may be unable to continue to make shareholder distributions at expected levels.    We intend to make regular quarterly cash distributions to our shareholders. However, distribution levels depend on a number of factors, some of which are beyond our control.

            Our loan agreements contain provisions that could restrict future distributions. Our ability to sustain our current distribution level will also be dependent, in part, on other matters, including:

      continued property occupancy and timely payment by tenants of rent obligations;

      the amount of future capital expenditures and expenses relating to our properties;

      the level of leasing activity and future rental rates;

      the strength of the commercial real estate market;

      our ability to compete;

      our costs of compliance with environmental and other laws;

      our corporate overhead levels;

      our amount of uninsured losses; and

      our decision to reinvest in operations rather than distribute available cash.

    15


              In addition, we can make distributions to the holders of our common shares only after we make preferential distributions to holders of our preferred shares.

              Our ownership limits are important factors.    Our Declaration of Trust limits ownership of our common shares by any single shareholder to 9.8% of the number of the outstanding common shares or 9.8% of the value of the outstanding common shares, whichever is more restrictive. Our Declaration of Trust also limits ownership by any single shareholder of our common and preferred shares in the aggregate to 9.8% of the aggregate value of the outstanding common and preferred shares. We call these restrictions the "Ownership Limit." Our Declaration of Trust allows our Board of Trustees to exempt shareholders from the Ownership Limit, and our Board of Trustees previously has exempted one entity from the Ownership Limit.

              Our Declaration of Trust includes other provisions that may prevent or delay a change of control.    Subject to the requirements of the New York Stock Exchange, our Board of Trustees has the authority, without shareholder approval, to issue additional securities on terms that could delay or prevent a change in control. In addition, our Board of Trustees has the authority to reclassify any of our unissued common shares into preferred shares. Our Board of Trustees may issue preferred shares with such preferences, rights, powers and restrictions as our Board of Trustees may determine, which could also delay or prevent a change in control.

              Our Board of Trustees is divided into three classes of Trustees, which could delay a change of control.    Our Declaration of Trust divides our Board of Trustees into three classes. The term of one class of the Trustees expires each year, at which time a successor class is elected for a term ending at the third succeeding annual meeting of shareholders. Such staggered terms make it more difficult for a third party to acquire control of us. On November 19, 2007, the Board of Trustees approved an amendment to the Declaration of Trust, subject to shareholder approval at the annual meeting of shareholders to be held on May 22, 2008, to eliminate the separate classes of Trustees and, instead, have all Trustees elected at each annual meeting of shareholders; if approved by the shareholders, all Trustees would be subject to re-election for a one-year term at the annual meeting of shareholders to be held in May 2009.

              The Maryland business statutes also impose potential restrictions on a change of control of our company.    Various Maryland laws may have the effect of discouraging offers to acquire us, even if the acquisition would be advantageous to shareholders. Resolutions adopted by our Board of Trustees and/or provisions of our bylaws exempt us from such laws, but our Board of Trustees can alter its resolutions or change our bylaws at any time to make these provisions applicable to us.

              Our failure to qualify as a REIT would have adverse tax consequences.    We believe that since 1992 we have qualified for taxation as a REIT for Federal income tax purposes. We plan to continue to meet the requirements for taxation as a REIT. Many of these requirements, however, are highly technical and complex. The determination that we are a REIT requires an analysis of various factual matters and circumstances that may not be totally within our control. For example, to qualify as a REIT, at least 95% of our gross income must come from certain sources that are itemized in the REIT tax laws. We are also required to distribute to shareholders at least 90% of our REIT taxable income (excluding capital gains). The fact that we hold most of our assets through our Operating Partnership and its subsidiaries further complicates the application of the REIT requirements. Even a technical or inadvertent mistake could jeopardize our REIT status. Furthermore, Congress and the Internal Revenue Service might make changes to the tax laws and regulations and the courts might issue new rulings that make it more difficult or impossible for us to remain qualified as a REIT.

              If we fail to qualify as a REIT, we would be subject to Federal income tax at regular corporate rates. Also, unless the Internal Revenue Service granted us relief under certain statutory provisions, we would remain disqualified as a REIT for four years following the year we first fail to qualify. If we fail

      16



      to qualify as a REIT, we would have to pay significant income taxes and would therefore have less money available for investments or for distributions to our shareholders. This would likely have a significant adverse effect on the value of our securities. In addition, we would no longer be required to make any distributions to our shareholders.

              We have certain distribution requirements that reduce cash available for other business purposes.    As a REIT, we must distribute at least 90% of our annual taxable income (excluding capital gains), which limits the amount of cash we have available for other business purposes, including amounts to fund our growth. Also, it is possible that because of the differences between the time we actually receive revenue or pay expenses and the period during which we report those items for distribution purposes, we may have to borrow funds to meet the 90% distribution requirement. We may also become subject to tax liabilities that adversely affect our operating cash flow and available cash for distribution to shareholders.

              A number of factors could cause our security prices to decline.    As is the case with any publicly-traded securities, certain factors outside of our control could influence the value of our common and preferred shares. These conditions include, but are not limited to:

        market perception of REITs in general and office REITs in particular;

        market perception of REITs relative to other investment opportunities;

        the level of institutional investor interest in our Company;

        general economic and business conditions;

        prevailing interest rates; and

        market perception of our financial condition, performance, dividends and growth potential.

              Generally, REITs are tax-advantaged relative to C corporations because they generally are not subject to corporate-level Federal income tax on income that they distribute to shareholders. However, Congress made changes to the tax laws and regulations that could make it less advantageous for investors to invest in REITs. The Jobs and Growth Tax Relief Reconciliation Act of 2003, or the 2003 Act, provides that generally for taxable years beginning after December 31, 2002 and before December 31, 2008, certain dividends received by domestic individual shareholders from certain C corporations are subject to a reduced rate of tax of up to 15%. Prior to the 2003 Act, such dividends received by domestic individual shareholders were generally subject to tax at ordinary income rates, which were as high as 38.6%. In general, the provisions of the 2003 Act do not benefit individual shareholders of REITs and could make an investment in a C corporation that is not a REIT more attractive than an investment in a REIT.

              The average daily trading volume of our common shares during the year ended December 31, 2007 was approximately 453,000 shares, and the average trading volume of our publicly-traded preferred shares is generally insignificant. As a result, relatively small volumes of transactions could have a pronounced effect on the market price of such shares.

              Our ability to pay dividends may be limited, and we cannot assure you that we will be able to pay dividends regularly.    Because we conduct substantially all of our operations through our Operating Partnership, our ability to pay dividends on any series of preferred shares will depend almost entirely on payments and dividends received on our interests in our Operating Partnership, the payment of which depends in turn on our ability to operate profitably and generate cash flow from our operations. We cannot guarantee that we will be able to pay dividends on a regular quarterly basis in the future. Additionally, the terms of some of the debt to which our Operating Partnership is a party limit its ability to make some types of payments and other dividends to us. This in turn limits our ability to make some types of payments, including payment of dividends on common or preferred shares, unless

      17



      we meet certain financial tests or such payments or dividends are required to maintain our qualification as a REIT. As a result, if we are unable to meet the applicable financial tests, we may not be able to pay dividends on our shares in one or more periods. Furthermore, any new shares of beneficial interest issued will substantially increase the cash required to continue to pay cash dividends at current levels. Any common or preferred shares of beneficial interest that may in the future be issued to finance acquisitions, upon exercise of options or otherwise, would have a similar effect.

              Our ability to pay dividends is further limited by the requirements of Maryland law.    Our ability to pay dividends on any series of preferred shares is further limited by the laws of Maryland. Under applicable Maryland law, a Maryland REIT may not make a distribution if, after giving effect to the distribution, the REIT would not be able to pay its debts as the debts become due in the usual course of business, or the REIT's total assets would be less than the sum of its total liabilities plus the amount that would be needed, if the REIT were dissolved at the time of the distribution, to satisfy the preferential rights upon dissolution of shareholders whose preferential rights are superior to those receiving the distribution. Accordingly, we may not make a distribution on any series of preferred shares if, after giving effect to the distribution, we would not be able to pay our debts as they become due in the usual course of business or our total assets would be less than the sum of our total liabilities plus the amount that would be needed to satisfy the preferential rights upon dissolution of the holders of shares of any series of preferred shares then outstanding, if any, with preferences senior to those of any such series of preferred shares.

              We may incur additional indebtedness, which may harm our financial position and cash flow and potentially impact our ability to pay dividends on any series of preferred shares.    Our governing documents do not limit us from incurring additional indebtedness and other liabilities. As of December 31, 2007, we had $1.8 billion of consolidated indebtedness outstanding. We may incur additional indebtedness and become more highly leveraged, which could harm our financial position and potentially limit our cash available to pay dividends. As a result, we may not have sufficient funds remaining to satisfy our dividend obligations relating to any series of preferred shares if we incur additional indebtedness.

              We are dependent on external sources of capital for future growth.    As noted above, because we are a REIT, we must distribute at least 90% of our annual taxable income to our shareholders. Due to this requirement, we will not be able to fund our acquisition, construction and development activities using cash flow from operations. Therefore, our ability to fund these activities is dependent on our ability to access capital funded by third parties. Such capital could be in the form of new debt, equity issuances of common shares, preferred shares, common and preferred units in our Operating Partnership or joint venture funding. Such capital may not be available on favorable terms or at all. Moreover, additional debt financing may substantially increase our leverage and subject us to covenants that restrict management's flexibility in directing our operations, and additional equity offerings may result in substantial dilution of our shareholders' interests. Our inability to obtain capital when needed could have a material adverse effect on our ability to expand our business and fund other cash requirements.

              Our business and operations would suffer in the event of system failures.    Despite system redundancy, the implementation of security measures and the existence of a disaster recovery plan for our internal information technology systems, our systems are vulnerable to damages from computer viruses, unauthorized access, energy blackouts, natural disasters, terrorism, war and telecommunication failures. Any system failure or accident that causes interruptions in our operations could result in a material disruption to our business. We may also incur additional costs to remedy damages caused by such disruptions.

              Certain of our officers and Trustees have potential conflicts of interest.    Certain of our officers and members of our Board of Trustees own partnership units in our Operating Partnership. These

      18



      individuals may have personal interests that conflict with the interests of our shareholders. For example, if our Operating Partnership sells or refinances certain of the properties that these officers or Trustees contributed to the Operating Partnership, the officers or Trustees could suffer adverse tax consequences. Their personal interests could conflict with our interests if such a sale or refinancing would be advantageous to us. We have certain policies in place that are designed to minimize conflicts of interest. We cannot, however, assure you that these policies will be successful in eliminating the influence of such conflicts, and if they are not successful, decisions could be made that might fail to reflect fully the interests of all of our shareholders.

              We are dependent on our key personnel, and the loss of any key personnel could have an adverse effect on our operations.    We are dependent on the efforts of our executive officers. The loss of any of their services could have an adverse effect on our operations. Although certain of our officers have entered into employment agreements with us, we cannot assure you that they will remain employed with us.

              We may change our policies without shareholder approval, which could adversely affect our financial condition, results of operations, market price of our common shares or ability to pay distributions.    Our Board of Trustees determines all of our policies, including our investment, financing and distribution policies. Although our Board of Trustees has no current plans to do so, it may amend or revise these policies at any time without a vote of our shareholders. Policy changes could adversely affect our financial condition, results of operations, the market price of our securities or distributions.

              Compliance with changing regulation of corporate governance and public disclosure may result in additional expenses, affect our operations and affect our reputation.    Changing laws, regulations and standards relating to corporate governance and public disclosure, including the Sarbanes-Oxley Act of 2002 and new SEC regulations and New York Stock Exchange rules, continue to create uncertainty for public companies. These new or changed laws, regulations and standards are subject to varying interpretations in many cases due to their lack of specificity, and as a result, their application in practice is evolving over time as new guidance is provided by regulatory and governing bodies, which could result in continuing uncertainty regarding compliance matters and higher costs necessitated by ongoing revisions to disclosure and governance practices. We are committed to maintaining high standards of corporate governance and public disclosure. As a result, our efforts to comply with evolving laws, regulations and standards have resulted in, and are likely to continue to result in, increased general and administrative expenses and a diversion of management time and attention from revenue-generating activities to compliance activities. In particular, our efforts to comply with Section 404 of the Sarbanes-Oxley Act of 2002 and the related regulations regarding our required assessment of our internal controls over financial reporting has required the commitment of significant financial and managerial resources. In addition, it has become more expensive for us to obtain director and officer liability insurance. We expect these efforts to require the continued commitment of significant resources. Further, our Trustees, Chief Executive Officer and Chief Financial Officer could face an increased risk of personal liability in connection with the performance of their duties. As a result, we may have difficulty attracting and retaining qualified Trustees and executive officers, which could harm our business. If our efforts to comply with new or changed laws, regulations and standards differ from the activities intended by regulatory or governing bodies due to ambiguities related to practice, our reputation may be harmed.

      Item 1B.    Unresolved Staff Comments

              None

      19


      Item 2.    Properties

              The following table provides certain information about our wholly owned office properties as of December 31, 2007:

      Property and Location

       Submarket
       Year
      Built/
      Renovated

       Rentable
      Square
      Feet

       Occupancy(1)
       Annualized
      Rental
      Revenue(2)

       Annualized
      Revenue per
      Occupied
      Square Foot(2)(3)

      Baltimore/Washington Corridor:              
       2730 Hercules Road
      Annapolis Junction, MD
       BWI Airport 1990 240,336 100.0%$5,719,779 $23.80
       304 Sentinel Drive
      Annapolis Junction, MD
       BWI Airport 2005 162,498 100.0% 4,462,970  27.46
       306 Sentinel Drive
      Annapolis Junction, MD
       BWI Airport 2006 157,896 100.0% 4,317,201  27.34
       2720 Technology Drive
      Annapolis Junction, MD
       BWI Airport 2004 156,730 100.0% 7,016,377  44.77
       2711 Technology Drive
      Annapolis Junction, MD
       BWI Airport 2002 152,000 100.0% 4,353,608  28.64
       320 Sentinel Way
      Annapolis Junction, MD
       BWI Airport 2007 125,681 100.0% 3,160,877  25.15
       318 Sentinel Way
      Annapolis Junction, MD
       BWI Airport 2005 125,681 100.0% 3,159,856  25.14
       322 Sentinel Way
      Annapolis Junction, MD
       BWI Airport 2006 125,568 100.0% 3,023,364  24.08
       140 National Business Parkway
      Annapolis Junction, MD
       BWI Airport 2003 119,904 100.0% 3,683,231  30.72
       132 National Business Parkway
      Annapolis Junction, MD
       BWI Airport 2000 118,598 100.0% 3,231,822  27.25
       2721 Technology Drive
      Annapolis Junction, MD
       BWI Airport 2000 118,093 100.0% 3,390,056  28.71
       2701 Technology Drive
      Annapolis Junction, MD
       BWI Airport 2001 117,450 100.0% 3,579,456  30.48
       1306 Concourse Drive
      Linthicum, MD
       BWI Airport 1990 114,046 94.8% 2,586,891  23.92
       870-880 Elkridge Landing Road
      Linthicum, MD
       BWI Airport 1981 105,151 100.0% 2,287,214  21.75
       2691 Technology Drive
      Annapolis Junction, MD
       BWI Airport 2005 103,683 100.0% 2,750,721  26.53
       1304 Concourse Drive
      Linthicum, MD
       BWI Airport 2002 101,710 76.7% 2,031,932  26.05
       900 Elkridge Landing Road
      Linthicum, MD
       BWI Airport 1982 97,261 91.5% 2,199,342  24.71
       1199 Winterson Road
      Linthicum, MD
       BWI Airport 1988 96,636 100.0% 2,454,431  25.40
       920 Elkridge Landing Road
      Linthicum, MD
       BWI Airport 1982 96,566 100.0% 1,762,329  18.25
       134 National Business Parkway
      Annapolis Junction, MD
       BWI Airport 1999 93,482 100.0% 2,571,315  27.51
       135 National Business Parkway
      Annapolis Junction, MD
       BWI Airport 1998 87,655 100.0% 2,491,462  28.42
       133 National Business Parkway
      Annapolis Junction, MD
       BWI Airport 1997 87,401 66.3% 1,676,398  28.92
       141 National Business Parkway
      Annapolis Junction, MD
       BWI Airport 1990 87,247 97.5% 2,172,909  25.54
       1302 Concourse Drive
      Linthicum, MD
       BWI Airport 1996 84,406 73.1% 1,500,457  24.31
       7467 Ridge Road
      Hanover, MD
       BWI Airport 1990 74,326 100.0% 1,773,426  23.86

      20


      Property and Location

       Submarket
       Year
      Built/
      Renovated

       Rentable
      Square
      Feet

       Occupancy(1)
       Annualized
      Rental
      Revenue(2)

       Annualized
      Revenue per
      Occupied
      Square Foot(2)(3)

       7240 Parkway Drive
      Hanover, MD
       BWI Airport 1985 73,970 76.3%1,275,642 22.60
       881 Elkridge Landing Road
      Linthicum, MD
       BWI Airport 1986 73,572 100.0%1,686,270 22.92
       1099 Winterson Road
      Linthicum, MD
       BWI Airport 1988 70,569 27.9%460,109 23.39
       1190 Winterson Road
      Linthicum, MD
       BWI Airport 1987 69,127 83.6%1,591,007 27.52
       131 National Business Parkway
      Annapolis Junction, MD
       BWI Airport 1990 69,039 90.5%1,737,422 27.80
       849 International Drive
      Linthicum, MD
       BWI Airport 1988 68,758 78.1%1,383,777 25.78
       911 Elkridge Landing Road
      Linthicum, MD
       BWI Airport 1985 68,296 100.0%1,463,145 21.42
       1201 Winterson Road
      Linthicum, MD
       BWI Airport 1985 67,903 100.0%1,018,545 15.00
       999 Corporate Boulevard
      Linthicum, MD
       BWI Airport 2000 67,455 91.8%1,863,299 30.09
       7272 Park Circle Drive
      Hanover, MD
       BWI Airport 1991/1996 59,397 74.4%964,031 21.83
       7318 Parkway Drive
      Hanover, MD
       BWI Airport 1984 59,204 100.0%1,131,240 19.11
       891 Elkridge Landing Road
      Linthicum, MD
       BWI Airport 1984 58,454 97.4%1,245,500 21.89
       7320 Parkway Drive
      Hanover, MD
       BWI Airport 1983 58,453 95.9%893,054 15.94
       901 Elkridge Landing Road
      Linthicum, MD
       BWI Airport 1984 57,593 100.0%1,236,781 21.47
       930 International Drive
      Linthicum, MD
       BWI Airport 1986 57,409 40.5%459,038 19.73
       800 International Drive
      Linthicum, MD
       BWI Airport 1988 57,379 100.0%1,192,555 20.78
       900 International Drive
      Linthicum, MD
       BWI Airport 1986 57,140 100.0%893,897 15.64
       921 Elkridge Landing Road
      Linthicum, MD
       BWI Airport 1983 54,175 100.0%1,083,500 20.00
       939 Elkridge Landing Road
      Linthicum, MD
       BWI Airport 1983 53,031 92.3%1,156,356 23.61
       938 Elkridge Landing Road
      Linthicum, MD
       BWI Airport 1984 52,988 100.0%1,244,390 23.48
       302 Sentinel Drive
      Annapolis Junction, MD
       BWI Airport 2007 48,377 100.0%1,745,545 36.08
       1340 Ashton Road
      Hanover, MD
       BWI Airport 1989 46,400 100.0%994,434 21.43
       1334 Ashton Road
      Hanover, MD
       BWI Airport 1989 37,565 36.7%258,159 18.72
       1331 Ashton Road
      Hanover, MD
       BWI Airport 1989 29,153 100.0%610,632 20.95
       5522 Research Park Drive
      Catonsville, MD
       BWI Airport 2007 23,500 100.0%599,250 25.50
       1350 Dorsey Road
      Hanover, MD
       BWI Airport 1989 19,992 52.9%187,923 17.77
       1344 Ashton Road
      Hanover, MD
       BWI Airport 1989 17,062 100.0%453,664 26.59
       1341 Ashton Road
      Hanover, MD
       BWI Airport 1989 15,841 100.0%300,103 18.94

      21


      Property and Location

       Submarket
       Year
      Built/
      Renovated

       Rentable
      Square
      Feet

       Occupancy(1)
       Annualized
      Rental
      Revenue(2)

       Annualized
      Revenue per
      Occupied
      Square Foot(2)(3)

       1343 Ashton Road
      Hanover, MD
       BWI Airport 1989 9,962 100.0%202,484 20.33
       114 National Business Parkway
      Annapolis Junction, MD
       BWI Airport 2002 9,908 100.0%210,523 21.25
       1348 Ashton Road
      Hanover, MD
       BWI Airport 1988 3,108 100.0%74,856 24.08
       7125 Columbia Gateway Drive
      Columbia, MD
       Howard County
      Perimeter
       1973/1999 611,379 97.5%8,247,531 13.84
       Old Annapolis Road
      Columbia, MD
       Howard County
      Perimeter
       1974/1985 171,436 100.0%5,306,078 30.95
       7200 Riverwood Drive
      Columbia, MD
       Howard County
      Perimeter
       1986 160,000 100.0%3,516,124 21.98
       7000 Columbia Gateway Drive
      Columbia, MD
       Howard County
      Perimeter
       1999 145,806 100.0%1,539,347 10.56
       6731 Columbia Gateway Drive
      Columbia, MD
       Howard County
      Perimeter
       2002 123,911 84.8%2,768,112 26.35
       6711 Columbia Gateway Drive
      Columbia, MD
       Howard County
      Perimeter
       2006/2007 123,410 83.1%2,710,744 26.44
       6940 Columbia Gateway Drive
      Columbia, MD
       Howard County
      Perimeter
       1999 109,003 73.9%1,941,628 24.11
       6950 Columbia Gateway Drive
      Columbia, MD
       Howard County
      Perimeter
       1998 107,778 100.0%2,364,513 21.94
       8621 Robert Fulton Drive
      Columbia, MD
       Howard County
      Perimeter
       2005/2006 86,032 96.1%1,672,423 20.23
       7067 Columbia Gateway Drive
      Columbia, MD
       Howard County
      Perimeter
       2001 82,953 41.0%748,110 22.00
       6750 Alexander Bell Drive
      Columbia, MD
       Howard County
      Perimeter
       2001 78,460 64.5%1,270,882 25.12
       6700 Alexander Bell Drive
      Columbia, MD
       Howard County
      Perimeter
       1988 74,859 91.8%1,609,776 23.43
       6740 Alexander Bell Drive
      Columbia, MD
       Howard County
      Perimeter
       1992 63,480 100.0%1,561,837 24.60
       7160 Riverwood Drive
      Columbia, MD
       Howard County
      Perimeter
       2000 62,084 86.7%1,131,734 21.03
       7015 Albert Einstein Drive
      Columbia, MD
       Howard County
      Perimeter
       1999 61,203 100.0%906,700 14.81
       8671 Robert Fulton Drive
      Columbia, MD
       Howard County
      Perimeter
       2002 56,350 100.0%1,066,614 18.93
       6716 Alexander Bell Drive
      Columbia, MD
       Howard County
      Perimeter
       1990 52,005 74.9%884,281 22.70
       8661 Robert Fulton Drive
      Columbia, MD
       Howard County
      Perimeter
       2002 49,307 100.0%857,364 17.39
       9020 Mendenhall Court
      Columbia, MD
       Howard County
      Perimeter
       1982/2005 49,259 82.4%509,208 12.54
       7130 Columbia Gateway Drive
      Columbia, MD
       Howard County
      Perimeter
       1989 46,840 99.2%764,439 16.45
       7142 Columbia Gateway Drive
      Columbia, MD
       Howard County
      Perimeter
       1994 45,951 0.0% 
       9140 Guilford Road
      Columbia, MD
       Howard County
      Perimeter
       1983 41,704 72.7%553,930 18.28
       7150 Riverwood Drive
      Columbia, MD
       Howard County
      Perimeter
       2000 41,382 100.0%661,518 15.99
       9720 Patuxent Woods Drive
      Columbia, MD
       Howard County
      Perimeter
       1986/2001 40,004 84.8%503,905 14.85
       6708 Alexander Bell Drive
      Columbia, MD
       Howard County
      Perimeter
       1988 39,203 100.0%831,809 21.22

      22


      Property and Location

       Submarket
       Year
      Built/
      Renovated

       Rentable
      Square
      Feet

       Occupancy(1)
       Annualized
      Rental
      Revenue(2)

       Annualized
      Revenue per
      Occupied
      Square Foot(2)(3)

       7065 Columbia Gateway Drive
      Columbia, MD
       Howard County
      Perimeter
       2000 38,560 100.0% 869,579  22.55
       9740 Patuxent Woods Drive
      Columbia, MD
       Howard County
      Perimeter
       1986/2001 38,292 100.0% 390,958  10.21
       7138 Columbia Gateway Drive
      Columbia, MD
       Howard County
      Perimeter
       1990 38,225 100.0% 821,278  21.49
       9160 Guilford Road
      Columbia, MD
       Howard County
      Perimeter
       1984 37,034 100.0% 745,983  20.14
       7063 Columbia Gateway Drive
      Columbia, MD
       Howard County
      Perimeter
       2000 36,813 100.0% 824,102  22.39
       6760 Alexander Bell Drive
      Columbia, MD
       Howard County
      Perimeter
       1991 36,440 96.3% 810,647  23.10
       7150 Columbia Gateway Drive
      Columbia, MD
       Howard County
      Perimeter
       1991 35,812 100.0% 646,989  18.07
       9700 Patuxent Woods Drive
      Columbia, MD
       Howard County
      Perimeter
       1986/2001 31,261 81.4% 551,740  21.69
       9730 Patuxent Woods Drive
      Columbia, MD
       Howard County
      Perimeter
       1986/2001 30,986 100.0% 448,791  14.48
       7061 Columbia Gateway Drive
      Columbia, MD
       Howard County
      Perimeter
       2000 29,910 100.0% 633,445  21.18
       7170 Riverwood Drive
      Columbia, MD
       Howard County
      Perimeter
       2000 29,162 87.9% 465,828  18.18
       6724 Alexander Bell Drive
      Columbia, MD
       Howard County
      Perimeter
       2001 28,420 100.0% 704,234  24.78
       7134 Columbia Gateway Drive
      Columbia, MD
       Howard County
      Perimeter
       1990 21,991 100.0% 396,899  18.05
       9150 Guilford Drive
      Columbia, MD
       Howard County
      Perimeter
       1984 18,592 100.0% 367,941  19.79
       10280 Old Columbia Road
      Columbia, MD
       Howard County
      Perimeter
       1988/2001 16,796 100.0% 249,544  14.86
       10270 Old Columbia Road
      Columbia, MD
       Howard County
      Perimeter
       1988/2001 16,686 100.0% 242,830  14.55
       9710 Patuxent Woods Drive
      Columbia, MD
       Howard County
      Perimeter
       1986/2001 15,229 100.0% 317,357  20.84
       9130 Guilford Drive
      Columbia, MD
       Howard County
      Perimeter
       1984 13,700 100.0% 263,734  19.25
       10290 Old Columbia Road
      Columbia, MD
       Howard County
      Perimeter
       1988/2001 10,890 60.4% 102,629  15.59
       2500 Riva Road
      Annapolis Junction, MD
       Annapolis 2000 155,000 100.0% 2,089,800  13.48
            
         
         
       Subtotal/Average     7,668,383 92.6%$162,847,470 $22.94
            
         
         

      Suburban Maryland:

       

       

       

       

       

       

       

       

       

       

       

       

       

       
       11800 Tech Road
      Silver Spring, MD
       North Silver Spring 1969/1989 228,179 100.0%$4,033,725 $17.68
       400 Professional Drive
      Gaithersburg, MD
       Gaithersburg 2000 129,311 100.0% 3,785,763  29.28
       110 Thomas Johnson Drive
      Frederick, MD
       Frederick 1987/1999 117,803 87.1% 2,508,702  24.45
       45 West Gude Drive
      Rockville, MD
       Rockville 1987 108,588 100.0% 2,135,904  19.67
       15 West Gude Drive
      Rockville, MD
       Rockville 1986 106,694 100.0% 2,506,625  23.49
            
         
         
       Subtotal/Average     690,575 97.8%$14,970,719 $22.17
            
         
         

      23


      Property and Location

       Submarket
       Year
      Built/
      Renovated

       Rentable
      Square
      Feet

       Occupancy(1)
       Annualized
      Rental
      Revenue(2)

       Annualized
      Revenue per
      Occupied
      Square Foot(2)(3)


      Suburban Baltimore:

       

       

       

       

       

       

       

       

       

       

       

       

       

       
       11311 McCormick Road
      Hunt Valley, MD
       Hunt Valley/Rte 83
      Corridor
       1984/1994 212,691 52.0%$2,541,792 $23.00
       10150 York Road
      Hunt Valley, MD
       Hunt Valley/Rte 83
      Corridor
       1985 178,286 100.0% 3,407,468  19.11
       9690 Deereco Road
      Timonium, MD
       Hunt Valley/Rte 83
      Corridor
       1988 134,167 100.0% 3,391,213  25.28
       200 International Circle
      Hunt Valley, MD
       Hunt Valley/Rte 83
      Corridor
       1987 128,658 56.9% 1,729,796  23.64
       375 W. Padonia Road
      Timonium, MD
       Hunt Valley/Rte 83
      Corridor
       1986 110,328 91.5% 1,631,943  16.17
       226 Schilling Circle
      Hunt Valley, MD
       Hunt Valley/Rte 83
      Corridor
       1980 98,640 100.0% 2,219,102  22.50
       201 International Circle
      Hunt Valley, MD
       Hunt Valley/Rte 83
      Corridor
       1982 78,634 79.7% 1,543,079  24.63
       11011 McCormick Road
      Hunt Valley, MD
       Hunt Valley/Rte 83
      Corridor
       1974 56,512 54.5% 515,191  16.73
       216 Schilling Circle
      Hunt Valley, MD
       Hunt Valley/Rte 83
      Corridor
       1988/2001 36,003 89.4% 656,811  20.40
       222 Schilling Circle
      Hunt Valley, MD
       Hunt Valley/Rte 83
      Corridor
       1978/1997 28,003 93.1% 546,709  20.97
       224 Schilling Circle
      Hunt Valley, MD
       Hunt Valley/Rte 83
      Corridor
       1978/1997 27,372 96.7% 484,681  18.31
       11101 McCormick Road
      Hunt Valley, MD
       Hunt Valley/Rte 83
      Corridor
       1976 24,232 88.4% 428,668  20.01
       7210 Ambassador Road
      Woodlawn, MD
       Baltimore County
      Westside
       1972 83,435 100.0% 899,161  10.78
       7152 Windsor Boulevard
      Woodlawn, MD
       Baltimore County
      Westside
       1986 57,855 100.0% 818,814  14.15
       21 Governor's Court
      Woodlawn, MD
       Baltimore County
      Westside
       1981/1995 56,063 64.6% 615,935  17.01
       7125 Ambassador Road
      Woodlawn, MD
       Baltimore County
      Westside
       1985 50,488 100.0% 935,564  18.53
       7253 Ambassador Road
      Woodlawn, MD
       Baltimore County
      Westside
       1988 38,930 100.0% 517,197  13.29
       7104 Ambassador Road
      Woodlawn, MD
       Baltimore County
      Westside
       1988 30,257 100.0% 511,693  16.91
       17 Governor's Court
      Woodlawn, MD
       Baltimore County
      Westside
       1981 14,619 100.0% 256,355  17.54
       15 Governor's Court
      Woodlawn, MD
       Baltimore County
      Westside
       1981 14,568 100.0% 213,725  14.67
       7127 Ambassador Road
      Woodlawn, MD
       Baltimore County
      Westside
       1985 11,144 64.9% 130,230  18.00
       7129 Ambassador Road
      Woodlawn, MD
       Baltimore County
      Westside
       1985 11,075 100.0% 171,663  15.50
       7108 Ambassador Road
      Woodlawn, MD
       Baltimore County
      Westside
       1988 9,018 47.1% 81,517  19.21
       7102 Ambassador Road
      Woodlawn, MD
       Baltimore County
      Westside
       1988 8,879 100.0% 169,282  19.07
       7106 Ambassador Road
      Woodlawn, MD
       Baltimore County
      Westside
       1988 8,820 100.0% 162,077  18.38
       7131 Ambassador Road
      Woodlawn, MD
       Baltimore County
      Westside
       1985 7,453 100.0% 128,931  17.30
       502 Washington Avenue
      Towson, MD
       Towson 1984 91,188 90.9% 1,731,588  20.89
       102 West Pennsylvania Avenue
      Towson, MD
       Towson 1968/2001 49,497 85.1% 797,253  18.92

      24


      Property and Location

       Submarket
       Year
      Built/
      Renovated

       Rentable
      Square
      Feet

       Occupancy(1)
       Annualized
      Rental
      Revenue(2)

       Annualized
      Revenue per
      Occupied
      Square Foot(2)(3)

       100 West Pennsylvania Avenue
      Towson, MD
       Towson 1952/1989 18,451 34.5%107,748 16.91
       109-111 Allegheny Avenue
      Towson, MD
       Towson 1971 18,431 100.0%244,885 13.29
       10001 Franklin Square Drive
      White Marsh, MD
       White Marsh 1997 216,000 83.7%1,475,910 8.16
       8140 Corporate Drive
      White Marsh, MD
       White Marsh 2003 75,687 85.6%1,575,287 24.32
       8110 Corporate Drive
      White Marsh, MD
       White Marsh 2001 75,687 100.0%1,571,524 20.76
       8031 Corporate Drive
      White Marsh, MD
       White Marsh 1988/2004 66,000 100.0%1,005,010 15.23
       7941-7949 Corporate Drive
      White Marsh, MD
       White Marsh 1996 57,600 100.0%589,722 10.24
       9910 Franklin Square Drive
      White Marsh, MD
       White Marsh 2005 56,271 100.0%1,073,023 19.07
       8020 Corporate Drive
      White Marsh, MD
       White Marsh 1997 51,600 100.0%834,741 16.18
       8094 Sandpiper Circle
      White Marsh, MD
       White Marsh 1998 50,812 100.0%979,868 19.28
       4979 Mercantile Road
      White Marsh, MD
       White Marsh 1985 50,498 100.0%662,607 13.12
       4940 Campbell Boulevard
      White Marsh, MD
       White Marsh 1990 49,813 90.6%966,910 21.43
       8098 Sandpiper Circle
      White Marsh, MD
       White Marsh 1998 47,680 100.0%761,422 15.97
       4969 Mercantile Road
      White Marsh, MD
       White Marsh 1983 47,574 100.0%740,651 15.57
       8114 Sandpiper Circle
      White Marsh, MD
       White Marsh 1986 45,399 87.1%966,522 24.45
       5020 Campbell Boulevard
      White Marsh, MD
       White Marsh 1986/1988 44,701 76.0%469,755 13.82
       9920 Franklin Square Drive
      White Marsh, MD
       White Marsh 2006 44,566 23.6%248,958 23.69
       8007 Corporate Drive
      White Marsh, MD
       White Marsh 1995 43,197 85.0%646,849 17.62
       9930 Franklin Square Drive
      White Marsh, MD
       White Marsh 2001 39,750 100.0%770,327 19.38
       8010 Corporate Drive
      White Marsh, MD
       White Marsh 1998 39,351 57.0%435,495 19.41
       8013 Corporate Drive
      White Marsh, MD
       White Marsh 1990 38,618 0.0% 
       8615 Ridgely's Choice Drive
      White Marsh, MD
       White Marsh 2005 37,797 52.3%383,971 19.42
       5325 Nottingham Ridge Road
      White Marsh, MD
       White Marsh 2002 37,322 75.5%559,322 19.85
       9900 Franklin Square Drive
      White Marsh, MD
       White Marsh 1999 33,912 100.0%624,525 18.42
       5024 Campbell Boulevard
      White Marsh, MD
       White Marsh 1986/1988 33,858 100.0%483,234 14.27
       9940 Franklin Square Drive
      White Marsh, MD
       White Marsh 2000 33,134 63.5%325,654 15.48
       5026 Campbell Boulevard
      White Marsh, MD
       White Marsh 1986/1988 30,868 73.6%425,472 18.72
       7939 Honeygo Boulevard
      White Marsh, MD
       White Marsh 1984 28,081 100.0%610,650 21.75

      25


      Property and Location

       Submarket
       Year
      Built/
      Renovated

       Rentable
      Square
      Feet

       Occupancy(1)
       Annualized
      Rental
      Revenue(2)

       Annualized
      Revenue per
      Occupied
      Square Foot(2)(3)

       8133 Perry Hall Boulevard
      White Marsh, MD
       White Marsh 1988 27,803 94.9% 518,194  19.64
       5022 Campbell Boulevard
      White Marsh, MD
       White Marsh 1986/1988 27,601 73.6% 299,812  14.76
       8019 Corporate Drive
      White Marsh, MD
       White Marsh 1990 25,461 100.0% 444,641  17.46
       8029 Corporate Drive
      White Marsh, MD
       White Marsh 1988/2004 25,000 100.0% 387,548  15.50
       7923 Honeygo Boulevard
      White Marsh, MD
       White Marsh 1985 24,053 100.0% 473,343  19.68
       8003 Corporate Drive
      White Marsh, MD
       White Marsh 1999 18,327 100.0% 345,209  18.84
       8015 Corporate Drive
      White Marsh, MD
       White Marsh 1990 16,610 100.0% 281,699  16.96
       8023 Corporate Drive
      White Marsh, MD
       White Marsh 1990 9,486 100.0% 147,087  15.51
            
         
         
       Subtotal/Average     3,243,814 84.8%$49,675,013 $18.06
            
         
         

      Greater Philadelphia:

       

       

       

       

       

       

       

       

       

       

       

       

       

       
       753 Jolly Road
      Blue Bell, PA
       Blue Bell 1960/92-94 419,472 100.0%$4,189,907 $9.99
       785 Jolly Road
      Blue Bell, PA
       Blue Bell 1970/1996 219,065 100.0% 2,515,223  11.48
       760 Jolly Road
      Blue Bell, PA
       Blue Bell 1974/1994 208,854 100.0% 3,068,118  14.69
       751 Jolly Road
      Blue Bell, PA
       Blue Bell 1966/1991 112,958 100.0% 1,128,284  9.99
            
         
         
       Subtotal/Average     960,349 100.0%$10,901,532 $11.35
            
         
         

      Central New Jersey:

       

       

       

       

       

       

       

       

       

       

       

       

       

       
       431 Ridge Road
      Dayton, NJ
       Exit 8A—Cranbury 1958/1998 171,200 100.0%$1,959,932 $11.45
       429 Ridge Road
      Dayton, NJ
       Exit 8A—Cranbury 1966/1996 142,385 21.1% 741,216  24.65
       47 Commerce
      Cranbury, NJ
       Exit 8A—Cranbury 1992/1998 41,398 100.0% 547,600  13.23
       437 Ridge Road
      Dayton, NJ
       Exit 8A—Cranbury 1962/1996 30,000 100.0% 291,300  9.71
            
         
         
       Subtotal/Average     384,983 70.8%$3,540,048 $12.98
            
         
         

      Northern Virginia:

       

       

       

       

       

       

       

       

       

       

       

       

       

       
       15000 Conference Center Drive
      Chantilly, VA
       Dulles South 1989 470,406 99.8%$11,083,480 $23.61
       15010 Conference Center Drive
      Chantilly, VA
       Dulles South 2006 223,610 100.0% 5,994,549  26.81
       15059 Conference Center Drive
      Chantilly, VA
       Dulles South 2000 145,192 100.0% 4,408,801  30.37
       15049 Conference Center Drive
      Chantilly, VA
       Dulles South 1997 145,053 100.0% 4,202,340  28.97
       14900 Conference Center Drive
      Chantilly, VA
       Dulles South 1999 127,115 81.3% 2,818,381  27.27
       14280 Park Meadow Drive
      Chantilly, VA
       Dulles South 1999 114,126 100.0% 3,266,499  28.62
       4851 Stonecroft Boulevard
      Chantilly, VA
       Dulles South 2004 88,094 100.0% 2,664,207  30.24

      26


      Property and Location

       Submarket
       Year
      Built/
      Renovated

       Rentable
      Square
      Feet

       Occupancy(1)
       Annualized
      Rental
      Revenue(2)

       Annualized
      Revenue per
      Occupied
      Square Foot(2)(3)

       14850 Conference Center Drive
      Chantilly, VA
       Dulles South 2000 69,711 100.0% 2,168,704  31.11
       14840 Conference Center Drive
      Chantilly, VA
       Dulles South 2000 69,710 100.0% 1,962,922  28.16
       13200 Woodland Park Drive
      Herndon, VA
       Herndon 2002 404,665 100.0% 11,279,746  27.87
       13454 Sunrise Valley Road
      Herndon, VA
       Herndon 1998 112,633 100.0% 2,744,755  24.37
       13450 Sunrise Valley Road
      Herndon, VA
       Herndon 1998 53,728 98.6% 1,270,169  23.98
       1751 Pinnacle Drive
      McLean, VA
       Tysons Corner 1989/1995 260,469 96.5% 8,205,927  32.65
       1753 Pinnacle Drive
      McLean, VA
       Tysons Corner 1976/2004 181,637 100.0% 6,399,128  35.23
            
         
         
       Subtotal/Average     2,466,149 98.6%$68,469,608 $28.16
            
         
         

      St. Mary's & King George Counties:

       

       

       

       

       

       

       

       

       

       

       

       

       

       
       22309 Exploration Drive
      Lexington Park, MD
       St. Mary's County 1984/1997 98,860 100.0%$1,442,239 $14.59
       46579 Expedition Drive
      Lexington Park, MD
       St. Mary's County 2002 61,156 87.3% 1,155,492  21.65
       22289 Exploration Drive
      Lexington Park, MD
       St. Mary's County 2000 61,059 94.9% 1,151,274  19.86
       46591 Expedition Drive
      Lexington Park, MD
       St. Mary's County 2005/2006 60,029 44.6% 537,242  20.05
       44425 Pecan Court
      California, MD
       St. Mary's County 1997 59,055 76.3% 878,010  19.48
       22299 Exploration Drive
      Lexington Park, MD
       St. Mary's County 1998 58,231 100.0% 1,313,856  22.56
       44408 Pecan Court
      California, MD
       St. Mary's County 1986 50,532 100.0% 585,573  11.59
       23535 Cottonwood Parkway
      California, MD
       St. Mary's County 1984 46,656 100.0% 527,349  11.30
       22300 Exploration Drive
      Lexington Park, MD
       St. Mary's County 1997 44,830 100.0% 697,884  15.57
       44417 Pecan Court
      California, MD
       St. Mary's County 1989 29,053 100.0% 278,900  9.60
       44414 Pecan Court
      California, MD
       St. Mary's County 1986 25,444 100.0% 243,557  9.57
       44420 Pecan Court
      California, MD
       St. Mary's County 1989 25,200 100.0% 173,148  6.87
       16480 Commerce Drive
      Dahlgren, VA
       King George
      County
       2000 70,728 100.0% 1,239,066  17.52
       16541 Commerce Drive
      King George, VA
       King George
      County
       1996 36,053 100.0% 523,144  14.51
       16539 Commerce Drive
      King George, VA
       King George
      County
       1990 32,076 70.9% 335,736  14.76
       16442 Commerce Drive
      Dahlgren, VA
       King George County 2002 25,518 100.0% 508,464  19.93
       16501 Commerce Drive
      Dahlgren, VA
       King George
      County
       2002 22,833 100.0% 519,304  22.74
       16543 Commerce Drive
      Dahlgren, VA
       King George
      County
       2002 17,370 87.0% 374,150  24.75
            
         
         
       
      Subtotal/Average

       

       

       

       

       

      824,683

       

      91.6

      %

      $

      12,484,388

       

      $

      16.54
            
         
         

      27


      Property and Location

       Submarket
       Year
      Built/
      Renovated

       Rentable
      Square
      Feet

       Occupancy(1)
       Annualized
      Rental
      Revenue(2)

       Annualized
      Revenue per
      Occupied
      Square Foot(2)(3)

       8611 Military Drive San Antonio 1982/1985 468,994 100.0%$7,231,868 $15.42
        San Antonio, TX     
         
         
      Colorado Springs:              
       985 Space Center Drive
      Colorado Springs, CO
       Colorado Springs
      East
       1989 102,717 98.9%$2,119,195 $20.86
       1670 North Newport Road
      Colorado Springs, CO
       Colorado Springs
      East
       1986/1987 67,500 100.0% 1,428,696  21.17
       745 Space Center Drive
      Colorado Springs, CO
       Colorado Springs
      East
       2006 51,500 100.0% 1,231,055  23.90
       1915 Aerotech Drive
      Colorado Springs, CO
       Colorado Springs
      East
       1985 37,946 85.8% 554,635  17.03
       1925 Aerotech Drive
      Colorado Springs, CO
       Colorado Springs
      East
       1985 37,946 100.0% 690,300  18.19
       980 Technology Court Colorado Springs, CO Colorado Springs
      East
       1995 33,190 100.0% 561,343  16.91
       525 Babcock Road
      Colorado Springs, CO
       Colorado Springs East 1967 14,000 100.0% 130,194  9.30
       9950 Federal Drive
      Colorado Springs, CO
       I-25 North Corridor 2001 66,222 83.6% 663,691  11.99
       9960 Federal Drive
      Colorado Springs, CO
       I-25 North Corridor 2001 46,948 100.0% 844,841  18.00
       9965 Federal Drive
      Colorado Springs, CO
       I-25 North Corridor 1983/2007 41,120 100.0% 624,084  15.18
       5775 Mark Dabling Boulevard
      Colorado Springs, CO
       Colorado Springs
      Northwest
       1984 109,678 100.0% 1,673,613  15.26
       5725 Mark Dabling Boulevard
      Colorado Springs, CO
       Colorado Springs
      Northwest
       1984 108,976 100.0% 2,050,233  18.81
       5755 Mark Dabling Boulevard
      Colorado Springs, CO
       Colorado Springs
      Northwest
       1989 105,210 90.4% 1,689,478  17.76
            
         
         
       Subtotal/Average     822,953 96.7%$14,261,358 $17.93
            
         
         

      Other:

       

       

       

       

       

       

       

       

       

       

       

       

       

       
       11751 Meadowville Lane
      Chester, VA
       Richmond
      Southwest
       2007 193,000 100.0%$5,133,615 $26.60
       201 Technology Park Drive
      Lebanon, VA
       Southwest Virginia 2007 102,842 100.0% 3,014,657  29.31
       607 Lakeside Drive
      Cascade, MD
       Fort Ritchie 1990/2007 4,904 100.0% 78,464  16.00
            
         
         
       Subtotal/Average     300,746 100.0%$8,226,736 $27.35
            
         
         
       Total/Average     17,831,629 92.6%$352,608,740 $21.36
            
         
         

      (1)
      This percentage is based upon all rentable square feet under lease terms that were in effect as of December 31, 2007.

      (2)
      Annualized rental revenue is the monthly contractual base rent as of December 31, 2007 multiplied by 12 plus the estimated annualized expense reimbursements under existing leases. We consider annualized rental revenue to be a useful measure for analyzing revenue sources because, since it is point-in-time based, it does not contain increases and decreases in revenue associated with periods in which lease terms were not in effect; historical revenue under GAAP does contain such fluctuations. We find the measure particularly useful for leasing, tenant, segment and industry analysis.

      (3)
      Annualized rental revenue per occupied square foot is the property's annualized rental revenue divided by that property's occupied square feet as of December 31, 2007.

      28


              The following table provides certain information about our wholly owned properties that are under construction, development and redevelopment as of December 31, 2007:

      Property and Location

       Submarket
       Estimated
      Rentable
      Square
      Feet Upon
      Completion

       Percentage
      Leased/
      Committed

       
      Under Construction       

      Baltimore/Washington Corridor:

       

       

       

       

       

       

       
       302 Sentinel Drive (302 NBP)
      Annapolis Junction, MD
       BWI Airport 157,146 51.33%
       5520 Research Park Drive (UMBC)
      Baltimore, MD
       BWI Airport 110,400 0.00%
       1362 Mellon Road
      Hanover, MD
       BWI Airport 44,134 0.00%
          
         
       Subtotal/Average    311,680 25.88%
          
         
      Colorado Springs:       
       655 Space Center Drive (Patriot Park 6)
      Colorado Springs, CO
       Colorado Springs East 103,970 72.14%
       1055 North Newport Road
      Colorado Springs, CO
       Colorado Springs East 59,763 100.00%
       9945 Federal Drive (Hybrid I)
      Colorado Springs, CO
       I-25 North Corridor 73,940 0.00%
       9925 Federal Drive (Hybrid II)
      Colorado Springs, CO
       I-25 North Corridor 53,845 0.00%
          
         
       Subtotal/Average    291,518 46.23%
          
         
      San Antonio:       
       8611 Military Drive, Building HI
      San Antonio, TX
       San Antonio 52,352 100.00%
       8611 Military Drive, Building C
      San Antonio, TX
       San Antonio 38,255 100.00%
          
         
       Subtotal/Average    90,607 100.00%
          
         
       Total Under Construction   693,805 44.11%
          
         
      Under Development       

      Baltimore/Washington Corridor:

       

       

       

       

       

       

       
       300 Sentinel Drive (300 NBP)
      Annapolis Junction, MD
       BWI Airport 190,000 N/A 
       324 Sentinel Drive (324 NBP)
      Annapolis Junction, MD
       BWI Airport 125,000 N/A 
       6721 Columbia Gateway Drive
      Columbia, MD
       Howard Co. Perimeter 125,000 N/A 
       Riverwood I & II
      Columbia, MD
       Howard Co. Perimeter 70,000 N/A 
          
         
       Subtotal/Average    510,000 N/A 
          
         
      Suburban Maryland:       
       110 Thomas Johnson Drive, Bldg #2
      Frederick, MD
       Frederick 85,000 N/A 
          
         
      Suburban Baltimore:       
       8130 Corporate Drive
      White Marsh, MD
       White Marsh 125,000 N/A 
       Northgate Business Park (Lot A)
      Aberdeen, MD
       Harford County 80,000 N/A 
          
         
       Subtotal/Average   205,000 N/A 
          
         
      St. Mary's & King George Counties:       
       16444 Commerce Drive
      Dahlgren, VA
       King George County 57,000 N/A 
          
         

      29


      Property and Location

       Submarket
       Estimated
      Rentable
      Square
      Feet Upon
      Completion

       Percentage
      Leased/
      Committed

       

      Colorado Springs:

       

       

       

       

       

       

       
       10807 New Allegiance Drive (Epic One)
      Colorado Springs, Colorado
       I-25 North Corridor 145,723 N/A 
       565 Space Center Drive (Patriot Park 7)
      Colorado Springs, Colorado
       Colorado Springs East 89,773 N/A 
          
         
       Subtotal/Average    235,496 N/A 
          
         
       Total Under Development   1,092,496 N/A 
          
         
      Under Redevelopment       

      Colorado Springs:

       

       

       

       

       

       

       
       
      9965 Federal Drive
      Colorado Springs, CO

       

      I-25 North Corridor

       

      74,749

       

      100.00

      %
          
         
       Total Under Redevelopment   74,749 100.00%
          
         

              The following table provides certain information about our wholly owned developable land holdings not under construction or development as of December 31, 2007:

      Land Location

       Submarket
       Acres
       Estimated
      Developable
      Square
      Feet

      Baltimore/Washington Corridor:      
       National Business Park (Phase III)
      Annapolis Junction, MD
       BWI Airport 194 1,125,000
       National Business Park (Phase II)
      Annapolis Junction, MD
       BWI Airport 30 730,165
       1460 Dorsey Road
      Hanover, MD
       BWI Airport 6 60,000
       940 Elkridge Landing Road (AS 7)
      Linthicum, MD
       BWI Airport 3 53,941
       1243 Winterson Road (AS 22)
      Linthicum, MD
       BWI Airport 2 30,000
       Columbia Gateway Parcel T-11
      Columbia, MD
       Howard Co. Perimeter 14 220,000
       7125 Columbia Gateway Drive
      Columbia, MD
       Howard Co. Perimeter 5 120,000
          
       
       Subtotal    254 2,339,106
          
       
      Northern Virginia:      
       Westfields Corporate Center
      Chantilly, VA
       Dulles South 32 674,200
       Westfields Corporate Center
      Chantilly, VA
       Dulles South 17 377,300
       Westfields Corporate Center
      Chantilly, VA
       Dulles South 19 246,800
       Woodland Park
      Herndon, VA
       Herndon 5 225,000
          
       
       Subtotal    73 1,523,300
          
       

      30


      Land Location

       Submarket
       Acres
       Estimated
      Developable
      Square
      Feet

      Suburban Maryland:      
       110 Thomas Johnson Drive
      Frederick, MD
       Frederick 3 85,000
       Rockville Corporate Center
      Rockville, MD
       Rockville 10 220,000
          
       
       Subtotal    13 305,000
          
       

      Suburban Baltimore:

       

       

       

       

       

       
       White Marsh
      White Marsh, MD
       White Marsh 145 1,567,000
       37 Allegheny Avenue(1)
      Towson, MD
       Towson  40,000
       Northgate Business Park
      Aberdeen, MD
       Harford County 51 720,000
          
       
       Subtotal    196 2,327,000
          
       

      St. Mary's & King George Counties:

       

       

       

       

       

       
       Dahlgren Technology Center
      Dahlgren, MD
       King George County 32 65,000
       Expedition Park
      Lexington Park, MD
       St. Mary's County 6 60,000
          
       
       Subtotal    38 125,000
          
       

      Colorado Springs:

       

       

       

       

       

       
       InterQuest
      Colorado Springs, CO
       I-25 North Corridor 111 1,626,492
       9965 Federal Drive
      Colorado Springs, CO
       I-25 North Corridor 4 30,000
       Patriot Park
      Colorado Springs, CO
       Colorado Springs East 71 770,000
       Aerotech Commerce
      Colorado Springs, CO
       Colorado Springs East 6 90,000
          
       
       Subtotal    192 2,516,492
          
       

      San Antonio:

       

       

       

       

       

       
       San Antonio
      San Antonio, TX
       San Antonio 31 375,000
       San Antonio
      San Antonio, TX
       San Antonio 27 350,000
          
       
       
      Subtotal

       

       

       

      58

       

      725,000
          
       

      Greater Philadelphia:

       

       

       

       

       

       
       Unisys Campus
      Blue Bell, PA
       Blue Bell 45 600,000
          
       

      Northern/Central New Jersey:

       

       

       

       

       

       
       Princeton Technology Center
      Cranbury, NJ
       Exit 8A—Cranbury 19 250,000
          
       

      Other:

       

       

       

       

       

       
       Fort Ritchie(2)
      Cascade, MD
       Cascade, MD 591 1,700,000
          
       
       Total Land   1,479 12,410,898
          
       

      (1)
      This property contains 0.3 of an acre.

      (2)
      The Fort Ritchie acquisition includes 301,134 square feet of existing office space targeted for future development (of which 3,014 square feet were leased as of December 31, 2007) and 110 existing usable residential units.

      31


              The following table provides certain information about our office properties owned through joint ventures as of December 31, 2007:

      Property and Location

       Submarket
       Year
      Built/
      Renovated

       Rentable
      Square
      Feet

       Occupancy(1)
       Annualized
      Rental
      Revenue(2)

       Annualized Rental
      Revenue per
      Occupied
      Square Foot(2)(3)

      Suburban Maryland:              
       4230 Forbes Boulevard
      Prince Georges, MD
       Lanham 2003 55,866 76.2%$671,487 $15.78
            
         
         

      Northern Virginia:

       

       

       

       

       

       

       

       

       

       

       

       

       

       
       2900 Towerview Road(4)
      Herndon, VA
       Route 28 South 1982 78,171 100.0%$1,005,389 $12.86
            
         
         

      Greater Harrisburg, Pennsylvania:

       

       

       

       

       

       

       

       

       

       

       

       

       

       
       2605 Interstate Drive
      Harrisburg, PA
       East Shore 1990 79,456 100.0%$1,451,661 $18.27
       6345 Flank Drive
      Harrisburg, PA
       East Shore 1989 69,443 88.5% 856,251  13.93
       6340 Flank Drive
      Harrisburg, PA
       East Shore 1988 68,200 100.0% 785,559  11.52
       2601 Market Place
      Harrisburg, PA
       East Shore 1989 65,411 87.1% 1,077,893  18.92
       6400 Flank Drive
      Harrisburg, PA
       East Shore 1992 52,439 77.8% 577,743  14.17
       6360 Flank Drive
      Harrisburg, PA
       East Shore 1988 46,500 86.0% 525,349  13.14
       6385 Flank Drive
      Harrisburg, PA
       East Shore 1995 32,921 20.6% 93,070  13.75
       6380 Flank Drive
      Harrisburg, PA
       East Shore 1991 32,668 100.0% 457,072  13.99
       6405 Flank Drive
      Harrisburg, PA
       East Shore 1991 32,000 100.0% 401,634  12.55
       95 Shannon Road
      Harrisburg, PA
       East Shore 1999 21,976 100.0% 394,919  17.97
       75 Shannon Road
      Harrisburg, PA
       East Shore 1999 20,887 100.0% 416,917  19.96
       6375 Flank Drive
      Harrisburg, PA
       East Shore 2000 19,783 100.0% 347,398  17.56
       85 Shannon Road
      Harrisburg, PA
       East Shore 1999 12,863 100.0% 231,154  17.97
       5035 Ritter Road
      Mechanicsburg, PA
       West Shore 1988 56,556 100.0% 908,500  16.06
       5070 Ritter Road—Building A
      Mechanicsburg, PA
       West Shore 1989 32,309 89.6% 407,249  14.06
       5070 Ritter Road—Building B
      Mechanicsburg, PA
       West Shore 1989 28,347 100.0% 409,525  14.45
            
         
         
      Subtotal/Average      671,759 90.5%$9,341,894 $15.37
            
         
         

      Total/Average

       

       

       

       

       

      805,796

       

      90.4

      %

      $

      11,018,770

       

      $

      15.13
            
         
         

      (1)
      This percentage is based upon all rentable square feet under lease terms that were in effect as of December 31, 2007.

      (2)
      Annualized rental revenue is the monthly contractual base rent as of December 31, 2007 multiplied by 12 plus the estimated annualized expense reimbursements under existing leases.

      (3)
      Annualized rental revenue per occupied square foot is the property's annualized rental revenue divided by that property's occupied square feet as of December 31, 2007.

      (4)
      This property totals 137,037 square feet, of which 58,866 is under redevelopment at December 31, 2007.

      32


              The following table provides certain information about our office properties owned through joint ventures that were under construction or redevelopment as of December 31, 2007:

      Property and Location

       Submarket
       Estimated Rentable Square Feet Upon Completion
       Percentage Leased/Committed
       
      Under Construction       

      Baltimore/Washington Corridor:

       

       

       

       

       

       

       
       7740 Milestone Parkway
      Hanover, MD
       BWI Airport 151,800 0.00%
          
         
       Total Under Construction   151,800 0.00%
          
         

      Under Redevelopment

       

       

       

       

       

       

       

      Baltimore/Washington Corridor:

       

       

       

       

       

       

       
       7468 Candlewood Road
      Hanover, MD
       BWI Airport 356,000 0.00%
          
         

      Northern Virginia:

       

       

       

       

       

       

       
       2900 Towerview Road(1)
      Herndon, VA
       Route 28 South 58,866 0.00%
       13849 Park Center Road
      Herndon, VA
       Route 28 South 57,000 N/A(2)
          
         
       Subtotal/Average    115,866 0.00%
          
         
       Total Under Redevelopment   471,866 0.00%
          
         

          (1)
          This property totals 137,037 square feet, of which 78,171 is operational at December 31, 2007.

          (2)
          As of December 31, 2007, we were under contract to sell 40,182 square feet in this property in 2008 and expect to complete the sale of the remaining square feet in 2008.

              The following table provides certain information about our developable land holdings owned through joint ventures that were not under construction or redevelopment as of December 31, 2007:

      Land Location

       Submarket
       Acres
       Estimated
      Developable
      Square
      Feet

      Baltimore/Washington Corridor:      
       Arundel Preserve
      Hanover, MD
       BWI Airport 56 1,648,200

      Other:

       

       

       

       

       

       
       Indian Head
      Charles County, MD
       Charles County MD 169 827,250
          
       
       
      Total Land

       

       

       

      225

       

      2,475,450
          
       

      33


      Lease Expirations

              The following table provides a summary schedule of the lease expirations for leases in place for our wholly owned properties as of December 31, 2007, assuming that none of the tenants exercise renewal options:

      Year of Lease Expiration(1)

       Number of Leases Expiring
       Square Footage of Leases Expiring
       Percentage of Total Occupied Square Feet
       Annualized Rental Revenue of Expiring Leases(2)
       Percentage of Total Annualized Rental Revenue Expiring(2)
       Total Annualized Rental Revenue of Expiring Leases per Occupied Square Foot
       
       (in thousands)

      2008 184 1,936,220 11.7%$39,323 11.2%$20.31
      2009 163 2,969,784 18.0% 50,387 14.3% 16.97
      2010 160 2,056,484 12.5% 46,978 13.3% 22.84
      2011 125 1,534,448 9.3% 30,644 8.7% 19.97
      2012 126 2,447,463 14.8% 51,997 14.7% 21.25
      2013 39 992,272 6.0% 22,824 6.5% 23.00
      2014 27 727,776 4.4% 20,769 5.9% 28.54
      2015 28 1,298,810 7.9% 30,784 8.7% 23.70
      2016 20 485,182 2.9% 12,054 3.4% 24.84
      2017 29 740,028 4.5% 18,595 5.3% 25.13
      2018 5 333,455 2.0% 8,566 2.4% 25.69
      2019 2 38,292 0.2% 391 0.1% 10.21
      2020   0.0%  0.0% 0.00
      2021 1 104,695 0.6% 2,454 0.7% 23.44
      2022 2 295,842 1.8% 8,148 2.3% 27.54
      2023   0.0%  0.0% 0.00
      2024   0.0%  0.0% 0.00
      2025 2 468,994 2.9% 7,232 2.1% 15.42
      Other(3) 22 80,222 0.5% 1,463 0.4% 18.24
        
       
       
       
       
         
      Total/Weighted Average 935 16,509,967 100.0%$352,609 100.0%$21.36
        
       
       
       
       
         

      (1)
      Most of our leases with the United States Government provide for consecutive one-year terms or provide for early termination rights. All of the leasing statistics set forth above assumed that the United States Government will remain in the space that it leases through the end of the respective arrangements, without ending consecutive one-year leases prematurely or exercising early termination rights. We reported the statistics in this manner because we manage our leasing activities using these same assumptions and believe these assumptions to be probable.

      (2)
      Annualized rental revenue is the monthly contractual base rent as of December 31, 2007 multiplied by 12, plus the estimated annualized expense reimbursements under existing office leases.

      (3)
      Other consists primarily of amenities, including cafeterias, concierge offices and property management space. In addition, month-to-month leases and leases that have expired but the tenant remains in holdover are included in this line item as the exact expiration date is unknown.

      Item 3.    Legal Proceedings

              Jim Lemon and Robin Biser, as plaintiffs, initiated a suit on May 12, 2005, in The United States District Court for the District of Columbia (Case No. 1:05CV00949), against The Secretary of the

      34



      United States Army, PenMar Development Corporation ("PMDC") and the Company, as defendants, in connection with the then pending acquisition by the Company of the former army base known as Fort Ritchie located in Cascade, Washington County, Maryland. The case was dismissed by the United States District Court on September 28, 2006, due to the plaintiffs' lack of standing. The plaintiffs filed an appeal in the case in the United States Court of Appeals for the District of Columbia Circuit and the Court of Appeals reversed the findings of the District Court and remanded the case to the District Court for further proceedings. The plaintiffs were unsuccessful in their request for an emergency injunction pending appeal. The Company acquired from PMDC fee simple title to 500 acres of the 591 acres comprising Fort Ritchie on October 5, 2006 and the remaining 91 acres on November 29, 2007.

              We are not currently involved in any other material litigation nor, to our knowledge, is any material litigation currently threatened against the Company (other than routine litigation arising in the ordinary course of business, substantially all of which is expected to be covered by liability insurance).

      Item 4.    Submission of Matters to a Vote of Security Holders

              Not applicable.


      PART II

      Item 5.    Market for Registrant's Common Equity, Related Stockholder Matters and Issuer Repurchases of Equity Securities

      Market Information

              Our common shares trade on the New York Stock Exchange ("NYSE") under the symbol "OFC." The table below shows the range of the high and low sale prices for our common shares as reported on the NYSE, as well as the quarterly common share dividends per share declared:

       
       Price Range
        
       
       Dividends Per Share
       
       Low
       High
      2006         
      First Quarter $34.91 $46.12 $0.280
      Second Quarter $37.32 $45.74 $0.280
      Third Quarter $40.65 $47.54 $0.310
      Fourth Quarter $44.21 $51.45 $0.310
       
       
       Price Range
        
       
       Dividends Per Share
       
       Low
       High
      2007         
      First Quarter $44.85 $56.45 $0.310
      Second Quarter $40.47 $48.81 $0.310
      Third Quarter $35.21 $44.63 $0.340
      Fourth Quarter $30.81 $45.39 $0.340

              The number of holders of record of our common shares was 401 as of December 31, 2007. This number does not include shareholders whose shares are held of record by a brokerage house or clearing agency, but does include any such brokerage house or clearing agency as one record holder.

              We will pay future dividends at the discretion of our Board of Trustees. Our ability to pay cash dividends in the future will be dependent upon: (i) the income and cash flow generated from our operations; (ii) cash generated or used by our financing and investing activities; and (iii) the annual distribution requirements under the REIT provisions of the Code described above and such other factors as the Board of Trustees deems relevant. Our ability to make cash dividends will also be limited

      35



      by the terms of our Operating Partnership Agreement and our financing arrangements, as well as limitations imposed by state law and the agreements governing any future indebtedness.

      Unregistered Sales of Equity Securities and Use of Proceeds

              During the three months ended December 31, 2007, 1,200 of the Operating Partnership's common units were exchanged for 1,200 common shares in accordance with the Operating Partnership's Second Amended and Restated Limited Partnership Agreement, as amended. The issuance of these common shares was effected in reliance upon the exemption from registration under Section 4(2) of the Securities Act of 1933, as amended.

      Common Shares Performance Graph

              The graph and the table set forth below assume $100 was invested on December 31, 2002 in the common shares of Corporate Office Properties Trust. The graph and the table compare the cumulative return (assuming reinvestment of dividends) of this investment with a $100 investment at that time in the S&P 500 Index or the All Equity REIT Index of the National Association of Real Estate Investment Trusts ("NAREIT"):

      LOGO

       
       Value at
      Index

       12/31/02
       12/31/03
       12/31/04
       12/31/05
       12/31/06
       12/31/07
      Corporate Office Properties Trust $100.00 $157.63 $228.82 $286.84 $418.15 $269.75
      S&P 500  100.00  128.68  142.69  149.70  173.34  182.86
      NAREIT All Equity REIT Index  100.00  137.13  180.44  202.38  273.34  230.45

      36


      Item 6.    Selected Financial Data

              The following table sets forth summary financial data as of and for each of the years ended December 31, 2003 through 2007. The table illustrates the significant growth our Company experienced over the periods reported. Most of this growth, particularly pertaining to revenues, operating income and total assets, was attributable to our addition of properties through acquisition and development activities. We financed most of the acquisition and development activities by incurring debt and issuing preferred and common equity, as indicated by the growth in our interest expense, preferred share dividends and weighted average common shares outstanding. The growth in our general and administrative expenses reflects, in large part, the growth in management resources required to support the increased size of our portfolio. Since this information is only a summary, you should refer to our Consolidated Financial Statements and notes thereto and the section of this report entitled "Management's Discussion and Analysis of Financial Condition and Results of Operations" for additional information.


      Corporate Office Properties Trust and Subsidiaries
      (in thousands, except per share data and number of properties)

       
       2007
       2006
       2005
       2004
       2003
       
      Revenues                
       Revenues from real estate operations(1) $368,949 $293,578 $236,809 $199,501 $159,767 
       Construction contract and other service operations revenues  41,225  60,084  79,234  28,903  31,740 
        
       
       
       
       
       
        Total revenues  410,174  353,662  316,043  228,404  191,507 
        
       
       
       
       
       
      Expenses                
       Property operating expenses(1)  123,282  92,907  70,337  57,888  46,513 
       Depreciation and other amortization associated with real estate operations(1)  106,331  78,054  60,427  48,708  34,019 
       Construction contract and other service operations expenses  39,793  57,345  77,287  26,996  30,933 
       General and administrative expenses  20,523  16,936  13,533  10,938  7,893 
        
       
       
       
       
       
        Total operating expenses  289,929  245,242  221,584  144,530  119,358 
        
       
       
       
       
       
      Operating income  120,245  108,420  94,459  83,874  72,149 
      Interest expense and amortization of deferred financing costs(1)  (85,708) (73,107) (56,135) (43,843) (40,662)
      Gain on sale of non-real estate investment  1,033         
        
       
       
       
       
       
      Income from continuing operations before equity in loss of unconsolidated entities, income taxes and minority interests  35,570  35,313  38,324  40,031  31,487 
      Equity in loss of unconsolidated entities  (224) (92) (88) (88) (98)
      Income tax (expense) benefit  (569) (887) (668) (795) 169 
        
       
       
       
       
       
      Income from continuing operations before minority interests  34,777  34,334  37,568  39,148  31,558 
      Minority interests in income from continuing operations(1)  (3,398) (3,826) (4,901) (5,029) (5,776)
        
       
       
       
       
       
      Income from continuing operations  31,379  30,508  32,667  34,119  25,782 
      Income from discontinued operations, net of minority interests(1)(2)  1,845  17,987  6,096  3,026  4,759 
      Gain (loss) on sales of real estate, net(1)(3)  1,560  732  268  (113) 336 
        
       
       
       
       
       
      Net income  34,784  49,227  39,031  37,032  30,877 
      Preferred share dividends  (16,068) (15,404) (14,615) (16,329) (12,003)
      Issuance costs associated with redeemed preferred shares(4)    (3,896)   (1,813)  
      Repurchase of preferred units in excess of recorded book value(5)          (11,224)
        
       
       
       
       
       
      Net income available to common shareholders $18,716 $29,927 $24,416 $18,890 $7,650 
        
       
       
       
       
       

      37


       
       2007
       2006
       2005
       2004
       2003
       
      Basic earnings per common share                
       Income from continuing operations $0.36 $0.29 $0.49 $0.48 $0.11 
       Net income available to common shareholders $0.40 $0.72 $0.65 $0.57 $0.29 
      Diluted earnings per common share                
       Income from continuing operations $0.35 $0.28 $0.47 $0.45 $0.10 
       Net income available to common shareholders $0.39 $0.69 $0.63 $0.54 $0.27 
      Weighted average common shares outstanding—basic  46,527  41,463  37,371  33,173  26,659 
      Weighted average common shares outstanding—diluted  47,630  43,262  38,997  34,982  28,021 
      Balance Sheet Data (as of year end):                
      Investment in real estate $2,603,472 $2,111,310 $1,888,106 $1,544,501 $1,189,258 
      Total assets $2,931,853 $2,419,601 $2,129,759 $1,732,026 $1,332,076 
      Debt $1,825,842 $1,498,537 $1,348,351 $1,022,688 $738,698 
      Total liabilities $1,979,116 $1,629,111 $1,442,036 $1,111,224 $801,899 
      Minority interests $130,095 $116,187 $105,210 $98,878 $79,796 
      Shareholders' equity $822,642 $674,303 $582,513 $521,924 $450,381 
      Other Financial Data (for the year ended):                
      Cash flows provided by (used in):                
       Operating activities $137,701 $113,151 $95,944 $84,494 $67,783 
       Investing activities $(327,714)$(253,834)$(420,301)$(268,720)$(172,949)
       Financing activities $206,728 $137,822 $321,320 $188,566 $108,656 
      Numerator for diluted EPS $18,716 $29,927 $24,416 $18,911 $7,650 
      Diluted funds from operations(6) $125,309 $98,937 $88,801 $76,248 $61,268 
      Diluted funds from operations per share(6) $2.24 $1.91 $1.86 $1.74 $1.56 
      Cash dividends declared per common share $1.30 $1.18 $1.07 $0.98 $0.91 
      Property Data (as of year end):                
      Number of properties owned(1)(7)  228  170  165  143  118 
      Total rentable square feet owned(1)(7)  17,832  15,050  13,708  11,765  9,876 

      (1)
      Certain prior period amounts pertaining to properties included in discontinued operations have been reclassified to conform with the current presentation. These reclassifications did not affect consolidated net income or shareholders' equity.

      (2)
      Reflects income derived from one operating real estate property that we sold in 2003, three operating real estate properties that we sold in 2005, seven operating real estate properties we sold in 2006, four operating real estate properties we sold in 2007 and one operating real estate property that we were under contract to sell as of December 31, 2007 that we classified as held for sale (see Note 18 to our Consolidated Financial Statements).

      (3)
      Reflects gain (loss) from sales of properties and unconsolidated real estate joint ventures not associated with discontinued operations.

      (4)
      Reflects a decrease to net income available to common shareholders pertaining to the original issuance costs recognized upon the redemption of the Series E and Series F Preferred Shares of beneficial interest in 2006 and the Series B Preferred Shares of beneficial interest in 2004.

      (5)
      Reflects a decrease to net income available to common shareholders representing the excess of the repurchase price of the Series C Preferred Units in our Operating Partnership over the sum of the recorded book value of the units and the accrued and unpaid return to the unitholder.

      (6)
      For definitions of diluted funds from operations per share and diluted funds from operations and reconciliations of these measures to their comparable measures under generally accepted accounting principles, you should refer to the section entitled "Funds from Operations" within the section entitled "Management's Discussion and Analysis of Financial Condition and Results of Operations."

      (7)
      Amounts reported reflect only wholly owned properties.

      38


      Item 7.    Management's Discussion and Analysis of Financial Condition and Results of Operations

              You should refer to our Consolidated Financial Statements and the notes thereto and our Selected Financial Data table as you read this section.

              This section contains "forward-looking" statements, as defined in the Private Securities Litigation Reform Act of 1995, that are based on our current expectations, estimates and projections about future events and financial trends affecting the financial condition and operations of our business. Forward-looking statements can be identified by the use of words such as "may," "will," "should," "expect," "estimate" or other comparable terminology. Forward-looking statements are inherently subject to risks and uncertainties, many of which we cannot predict with accuracy and some of which we might not even anticipate. Although we believe that the expectations, estimates and projections reflected in such forward-looking statements are based on reasonable assumptions at the time made, we can give no assurance that these expectations, estimates and projections will be achieved. Future events and actual results may differ materially from those discussed in the forward-looking statements. Important factors that may affect these expectations, estimates and projections include, but are not limited to:

        our ability to borrow on favorable terms;

        general economic and business conditions, which will, among other things, affect office property demand and rents, tenant creditworthiness, interest rates and financing availability;

        adverse changes in the real estate markets, including, among other things, increased competition with other companies;

        risks of real estate acquisition and development activities, including, among other things, risks that development projects may not be completed on schedule, that tenants may not take occupancy or pay rent or that development and operating costs may be greater than anticipated;

        risks of investing through joint venture structures, including risks that our joint venture partners may not fulfill their financial obligations as investors or may take actions that are inconsistent with our objectives;

        our ability to satisfy and operate effectively under federal income tax rules relating to real estate investment trusts and partnerships;

        governmental actions and initiatives; and

        environmental requirements.

      We undertake no obligation to update or supplement forward-looking statements.

      Overview

              We are a real estate investment trust ("REIT") that focuses on the acquisition, development, ownership, management and leasing of suburban office properties in select markets and submarkets. We also focus on servicing the multi-location requirements of strategic customers and strategic industries in which tenants have specialized product requirements. Our properties are typically concentrated in large office parks located in demographically strong markets and submarkets where we believe we can achieve critical mass, operating synergies and key competitive advantages, including attracting high quality tenants and securing acquisition and development opportunities, and/or located near demand drivers for strategic customers and industries. As of December 31, 2007, our investments in real estate included the following:

        228 wholly owned operating properties totaling 17.8 million square feet;

        19 wholly owned properties under construction or development that we estimate will total approximately 1.8 million square feet upon completion and one wholly owned office property totaling 74,749 square feet that was under redevelopment;

        wholly owned land parcels totaling 1,479 acres that we believe are potentially developable into approximately 12.4 million square feet; and

      39


          partial ownership interests in a number of other real estate projects in operations, under construction or redevelopment or held for future development.

                REITs were created by the United States Congress in order to provide large numbers of investors with the ability to make investments into entities that own large scale commercial real estate. One unique aspect of a REIT is that the entity typically does not pay corporate income tax, provided that the entity distributes 100% of its taxable income to its shareholders and meets a number of other specific requirements of the Internal Revenue Code of 1986, as amended (it is noteworthy that REITs are required to distribute a minimum of only 90% of taxable income to maintain their tax status as a REIT, although any differential between the 90% and 100% would be taxable). Most of our revenues relating to our real estate operations are derived from rents and property operating expense reimbursements earned from tenants leasing space in our properties. Most of our expenses relating to our real estate operations take the form of: (1) property operating costs, such as real estate taxes, utilities and repairs and maintenance; (2) financing costs, such as interest and loan costs; and (3) depreciation and amortization associated with our operating properties.

                Of the 228 wholly owned operating properties in our portfolio, 213 were located in the Mid-Atlantic region of the United States. Our primary regions as of December 31, 2007 are set forth below:

          Baltimore/Washington Corridor (generally defined as the Maryland counties of Howard and Anne Arundel);

          Northern Virginia (defined as Fairfax County, Virginia);

          Suburban Maryland (defined as the Maryland counties of Montgomery, Prince George's and Frederick);

          St. Mary's & King George Counties (located in Maryland and Virginia, respectively);

          Suburban Baltimore, Maryland (generally defined as the Maryland counties of Baltimore and Harford)("Suburban Baltimore");

          Colorado Springs, Colorado ("Colorado Springs");

          San Antonio, Texas ("San Antonio");

          Greater Philadelphia, Pennsylvania ("Greater Philadelphia"); and

          Northern/Central New Jersey (as of December 31, 2007, all of our properties in this segment were located in Central New Jersey).

                As of December 31, 2007, 138 of our properties were located in what is widely known as the Greater Washington, D.C. region, which includes the first four regions set forth above, and 64 were located in neighboring Suburban Baltimore. At December 31, 2007, we also owned 13 wholly owned properties in Colorado Springs and two in San Antonio. In addition, we owned eight properties in total as of December 31, 2007 in the last two locations set forth above that are considered non-core to the Company. The most significant change in our geographical concentration in 2007 occurred as a result of our completion of the Nottingham Acquisition (discussed below), which approximately doubled our concentration in the Suburban Baltimore region. We discuss further the geographic concentrations of our property ownership in the section below entitled "Concentration of Operations."

                Part of our strategy for operations and growth focuses on establishing, maintaining and expanding strategic customer relationships in multiple locations to make us the landlord of choice for such customers. As a result of this strategy, a large concentration of our revenue is derived from several large tenants. Our largest tenants are also heavily concentrated with the United States defense industry,

        40


        with such tenants predominantly concentrated in the area of defense information technology. Several noteworthy statistics that demonstrate our tenant and industry concentrations are set forth below:

         
         Percentage of Annualized Rental Revenue(1) of Wholly Owned Properties at December 31, 2007
         
        Largest tenant, United States Government 16.3%
        Five largest tenants 35.0%
        Twenty largest tenants 54.8%
        Tenants in the United States defense industry 47.9%

            (1)
            Defined below in the section entitled "Concentration of Operations."

        We discuss further our lease concentrations in the section below entitled "Concentration of Operations."

                In order to maximize the revenue potential of our properties, we try to maintain high levels of occupancy; as a result, we consider occupancy rates to be an important measure of the productivity of our properties. One way that we attempt to maximize occupancy rates is by renewing a high percentage of our existing tenants; accordingly, tenant renewal rates are important to us in monitoring our leasing activities and tenant relationships. In managing the effect of our leasing activities on our financial position and future operating performance stability, we also monitor the timing of our lease maturities with the objective that the timing of such maturities not be highly concentrated in a given one-year or five-year period. The table below sets forth certain occupancy and leasing information as of or for the year ended December 31, 2007 for our portfolio of wholly owned properties:

        Occupancy  92.6%
        Renewal rate of square footage for scheduled lease expirations during year  69.1%
        Average contractual annual rental rate per square foot(1) $21.36 
        Weighted average lease term (in years)(2)  5.0 

            (1)
            Includes estimated expense reimbursements.

            (2)
            See assumption relating to our United States Government leases in the section entitled "Results of Operations," in the subsection entitled "Occupancy and Leasing."

        We discuss further in the section below entitled "Results of Operations," in the subsection entitled "Occupancy and Leasing."

                Achieving optimal performance from our properties is highly important to us. We evaluate the performance of our properties by focusing on changes in revenues from real estate operations (comprised of (1) rental revenue and (2) tenant recoveries and other real estate operations revenue) and property operating expenses. However, since we have experienced significant growth in a number of operating properties, assessing performance from our growth in revenues from real estate operations and property operating expenses without further analysis of the components of such growth can be misleading. Therefore, we evaluate (1) changes in revenues from real estate operations and property operating expenses attributable to property additions separately from (2) the changes attributable to properties that were owned and 100% operational throughout any two periods being compared (properties that we collectively refer to as the Same-Office Properties). During 2007, we:

          experienced significant growth from 2006 in revenues from real estate operations and property operating expenses due primarily to the addition of properties through acquisition and construction activities since January 1, 2006;

        41


            had a $9.3 million, or 3.4%, increase in revenues from the Same-Office Properties compared to 2006 due primarily to a 2.1% increase in rental revenue and an 11.9% increase in operating expense reimbursements at such properties; and

            had a $6.9 million, or 7.8%, increase in property operating expenses from the Same-Office Properties compared to 2006 due in large part to increased utilities, snow removal costs, real estate taxes and certain other repairs and maintenance expenses.

          We discuss these changes further in the section below entitled "Results of Operations," in the subsection entitled "Revenues from Real Estate Operations and Property Operating Expenses."

                  In addition to owning real estate properties, we provide real estate-related services that include: (1) property management; (2) construction and development management; and (3) heating and air conditioning services and controls. The gross revenue and costs associated with these services generally bear little relationship to the level of our activity from these operations since a substantial portion of the costs are subcontracted costs that are reimbursed to us by the customer at no mark up. As a result, the operating margins from these operations are small relative to the revenue. We use the net of such revenues and expenses to evaluate the performance of our service operations. For 2007, the operating margins of our service operations decreased $1.3 million compared to 2006 due primarily to: (1) a slow down in activity on certain third party constructions jobs; and (2) a decrease in third party work for heating and air conditioning controls and plumbing services. These operations are discussed further in the section below entitled "Results of Operations," in the subsection entitled "Construction Contract and Other Service Revenue and Expenses."

                  Our 2007 net income available to common shareholders decreased 37.5% and our diluted earnings per share decreased 43.5% compared to 2006. We discuss significant factors contributing to these changes within subsections of the section below entitled "Results of Operations."

                  The investment portion of our growth strategy focuses primarily on two activities: acquisitions and property development. These activities typically target suburban office properties in our existing geographic regions, neighboring regions or new regions meeting our investment criteria, but they may also target other properties that meet the multi-location requirements of our strategic customers and strategic industries. Since we take an opportunistic yet disciplined approach to our investment activities, the volume of these activities and allocation between acquisitions versus development naturally change from year to year. Highlights of our 2007 acquisition and development activities are set forth below:

            we acquired 56 operating properties totaling approximately 2.4 million square feet and land parcels totaling 187 acres in a series of transactions that we refer to collectively as the Nottingham Acquisition for an aggregate cost of $366.9 million. All of the acquired properties are located in Maryland with 36 of the operating properties, totaling 1.6 million square feet, and land parcels totaling 175 acres, located in White Marsh, Maryland (located in the Suburban Baltimore region) and the remaining properties and land parcels located in other regions in Northern Baltimore County and the Baltimore/Washington Corridor. We believe that the land parcels can support at least 2.0 million developable square feet;

            we acquired the remaining 50% undivided interest in a 132-acre parcel of land located in Colorado Springs that we believe can support approximately 1.9 million developable square feet of office space for $13.6 million;

            we acquired a 56-acre parcel of land located in Aberdeen, Maryland that we believe can support up to 800,000 developable square feet for $10.5 million (Aberdeen, Maryland is located in our Suburban Baltimore region). The property is located adjacent to Aberdeen Proving Ground, which is a United States Government installation;

            we had five newly constructed properties totaling 568,433 square feet become fully operational (68,196 of these square feet were placed into service in 2006). We also had 48,377 square feet placed into service in one partially operational property;

          42


              we had 10 properties under construction (nine wholly owned), 10 properties under development (all wholly owned) and four properties under redevelopment (one wholly owned) at December 31, 2007; and

              we had land parcels totaling 1,704 acres (of which 1,479 acres were wholly owned) that were potentially developable into 14.9 million square feet (of which 12.4 million square feet pertained to wholly owned acres).

                    While we generally do not acquire properties with the intent of selling them, we do sell properties from time to time when we believe that most of the earnings growth potential in those properties have been realized, or determine that the property no longer fits within our strategic plans due to its type and/or location. During 2007, we sold four operating properties totaling 128,000 square feet (including two from one of our non-core regions and one acquired in the Nottingham Acquisition) and three parcels of land acquired in the Nottingham Acquisition totaling approximately 16 acres and developable into approximately 230,000 square feet for a total of $26.5 million, resulting in recognized gains before minority interest and taxes on gain on sale of real estate totaling $6.9 million (we incurred $1.1 million in income tax expense on these sales due primarily to built in gains that existed for certain of these properties).

                    Our financing policy is aimed at maintaining a flexible capital structure in order to facilitate consistent growth and performance in the face of differing market conditions in the most cost-effective manner. As part of this policy, we monitor: (1) levels of debt relative to our overall capital structure; (2) the relationship of certain measures of earnings to certain financing cost requirements (coverage ratios); (3) the relationship of our total variable-rate debt to our total debt; and (4) the timing of our debt maturities to ensure that the maximum maturities of debt in any year do not exceed a defined percentage of total assets. We also pursue opportunities, when we believe market conditions to be favorable, to: (1) reduce financing costs by refinancing existing debt or redeeming existing preferred equity; (2) issue common and preferred shares of beneficial interest ("common shares" and "preferred shares"); (3) issue equity units in our Operating Partnership; and (4) reduce our equity investment requirements in certain properties through the use of joint venture structures. Highlights of our 2007 financing activities are set forth below:

              we financed a portion of the Nottingham Acquisition by issuing common shares to the seller at a value of $156.7 million, or $49.57 per share, and issuing $26.6 million in Series K Cumulative Redeemable Convertible Preferred Shares of beneficial interest (the "Series K Preferred Shares") to the seller at a value of, and liquidation preference equal to, $50 per share. We also issued 262,165 common units valued at $12.1 million, in connection with the acquisition of the remaining 50% undivided interest in the 132-acre parcel of land in Colorado Springs described above;

              we amended and restated the credit agreement on our Revolving Credit Facility on October 1, 2007, increasing the amount of the lenders' aggregate commitment under the facility from $500.0 million to $600.0 million, with a right for us to further increase the lenders' aggregate commitment during the term to a maximum of $800.0 million, subject to certain conditions. The facility matures on September 30, 2011, and may be extended by us for a period of one year, subject to certain conditions; and

              we borrowed $150.0 million under a mortgage loan with a 10-year term at a fixed rate of 5.65%.

                    We discuss our 2007 investing and financing activities further in the section below entitled "Liquidity and Capital Resources," along with discussions of, among other things, the following:

              our cash flows;

              how we expect to generate cash for short and long-term capital needs;

              our off-balance sheet arrangements in place that are reasonably likely to affect our financial condition;

              our commitments and contingencies; and

              the computation of our Funds from Operations.

            43


              Critical Accounting Policies and Estimates

                      Our Consolidated Financial Statements are prepared in accordance with generally accepted accounting principles in the United States of America ("GAAP"), which require us to make certain estimates and assumptions. A summary of our significant accounting policies is provided in Note 2 to our Consolidated Financial Statements. The following section is a summary of certain aspects of those accounting policies involving estimates and assumptions that (1) require our most difficult, subjective or complex judgments in accounting for highly uncertain matters or matters that are susceptible to change and (2) materially affect our reported operating performance or financial condition. It is possible that the use of different reasonable estimates or assumptions in making these judgments could result in materially different amounts being reported in our Consolidated Financial Statements. While reviewing this section, you should refer to Note 2 to our Consolidated Financial Statements, including terms defined therein.

                When we acquire real estate properties, we allocate the acquisition to numerous tangible and intangible components. Most of the terms in this bullet section are defined in the section of Note 2 to the Consolidated Financial Statements entitled "Acquisitions of Real Estate." Our process for determining the allocation to these components is very complex and requires many estimates and assumptions. Included among these estimates and assumptions are the following: (1) determination of market rental rates; (2) estimation of leasing and tenant improvement costs associated with the remaining term of acquired leases for deemed cost avoidance; (3) leasing assumptions used in determining the lease-up value, as-if vacant value and tenant relationship value, including the rental rates, period of time that it will take to lease vacant space and estimated tenant improvement and leasing costs; (4) estimation of the property's future value in determining the as-if vacant value; (5) estimation of value attributable to market concentration premiums and tenant relationship values; and (6) allocation of the as-if vacant value between land and building. A change in any of the above key assumptions, most of which are extremely subjective, can materially change not only the presentation of acquired properties in our Consolidated Financial Statements but also reported results of operations. The allocation to different components affects the following:

                the amount of the acquisition costs allocated among different categories of assets and liabilities on our balance sheet; the amount of costs assigned to individual properties in multiple property acquisitions; and the amount of costs assigned to individual tenants at the time of acquisition;

                where the amortization of the components appear over time in our Consolidated Statements of Operations. Allocations to the lease to market value component are amortized into rental revenue, whereas allocations to most of the other components (the one exception being the land component of the as-if vacant value) are amortized into depreciation and amortization expense. As a REIT, this is important to us since much of the investment community evaluates our operating performance using non-GAAP measures such as funds from operations, the computation of which includes rental revenue but does not include depreciation and amortization expense; and

                the timing over which the items are recognized as revenue or expense in our Consolidated Statements of Operations. For example, for allocations to the as-if vacant value, the land portion is not depreciated and the building portion is depreciated over a longer period of time than the other components (generally 40 years). Allocations to lease to market value, deemed cost avoidance, lease-up value and tenant relationship value are amortized over significantly shorter timeframes, and if individual tenants' leases are terminated early, any unamortized amounts remaining associated with those tenants are generally expensed upon termination. These differences in timing can materially affect our reported results of operations. In addition, we establish lives for lease-up value and tenant relationship value

              44


                    based on our estimates of how long we expect the respective tenants to remain in the properties; establishing these lives requires estimates and assumptions that are very subjective.

                When events or circumstances indicate that a property may be impaired, we perform an undiscounted cash flow analysis. We consider an asset to be impaired when its undiscounted expected future cash flows are less than its depreciated cost. If such an impairment is present, an impairment loss is recognized based on the excess of the carrying amount of the asset over its fair value. We compute a real estate asset's undiscounted expected future cash flows and fair value using certain estimates and assumptions. As a result, these estimates and assumptions impact whether an impairment is deemed to have occurred and the amount of impairment loss that we recognize.

                We generally use three different accounting methods to report our investments in entities: the consolidation method; the equity method; and the cost method (see Note 2 to our Consolidated Financial Statements). We generally use the consolidation method when we own most of the outstanding voting interests in an entity and can control its operations. In accordance with Financial Accounting Standards Board ("FASB") Interpretation No. 46(R), "Consolidation of Variable Interest Entities" ("FIN 46(R)"), we also consolidate certain entities when control of such entities can be achieved through means other than voting rights ("variable interest entities" or "VIEs") if we are deemed to be the primary beneficiary. Generally, FIN 46(R) applies when either (1) the equity investors (if any) lack one or more of the essential characteristics of a controlling financial interest; (2) the equity investment at risk is insufficient to finance that entity's activities without additional subordinated financial support; or (3) the equity investors have voting rights that are not proportionate to their economic interests and the activities of the entity involve, or are conducted on behalf of, an investor with a disproportionately small voting interest. We generally use the equity method of accounting when we own an interest in an entity and can exert significant influence over, but cannot control, the entity's operations. In making these determinations, we typically need to make subjective estimates and judgments regarding the entity's future operating performance, financial condition, future valuation and other variables that may affect the partners' share of cash flow from the entity over time. We also need to estimate the probability of different scenarios taking place over time and project the effect that each of those scenarios would have on variables affecting the partners' cash flows. The conclusion reached as a result of this process affects whether or not we use the consolidation method in accounting for our investment or the equity method. Whether or not we consolidate an investment can materially affect our Consolidated Financial Statements.

                We issue options to purchase common shares ("options") and restricted common shares ("restricted shares") to many of our employees. Prior to January 1, 2006, very little expense was required to be recognized in our financial statements for options under GAAP. On January 1, 2006, we adopted Statement of Financial Accounting Standards No. 123(R), "Share-Based Payment" ("SFAS 123(R)"). SFAS 123(R) requires us to measure the cost of employee services received in exchange for an award of equity instruments based generally on the fair value of the award on the grant date; such cost should then be recognized over the period during which the employee is required to provide service in exchange for the award (generally the vesting period). We compute the grant date fair value of options using the Black-Scholes option-pricing model, which requires the following input assumptions: risk-free interest rate; expected life; expected volatility; and expected dividend yield. SFAS 123(R) also requires that share-based compensation be computed based on awards that are ultimately expected to vest; as a result, future forfeitures of our options and restricted shares are to be estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. The input assumptions used under the Black-Scholes option-pricing model and the estimates used in deriving the forfeiture rates for options and restricted common shares are subjective and require

              45


                  a fair amount of judgment. As a result, these estimates and assumptions can affect the amount of expense that we recognize in our Consolidated Financial Statements for options and restricted shares.

              Concentration of Operations

                      One measure that we refer to in various sections of the Management's Discussion and Analysis of Financial Condition and Results of Operations section of this Annual Report on Form 10-K is annualized rental revenue. Annualized rental revenue is a measure that we use to evaluate the source of our rental revenue as of a point in time. It is computed by multiplying by 12 the sum of monthly contractual base rents and estimated monthly expense reimbursements under active leases as of a point in time. We consider annualized rental revenue to be a useful measure for analyzing revenue sources because, since it is point-in-time based, it does not contain increases and decreases in revenue associated with periods in which lease terms were not in effect; historical revenue under GAAP does contain such fluctuations. We find the measure particularly useful for leasing, tenant, segment and industry analysis.

                Geographic Concentration of Property Operations

                      Our market strategy is to concentrate our operations in select markets and submarkets where we believe we already possess or can achieve the critical mass necessary to maximize management efficiencies, operating synergies and competitive advantages through our acquisition, property management, leasing and development programs. A result of this strategy is that our property positions and operations are highly concentrated in a small number of geographic regions. The table below sets forth the regional allocation of our annualized rental revenue as of the end of the last three calendar years:

               
               Percentage of Annualized Rental Revenue of
              Wholly Owned Properties
              as of December 31,

               Number of
              Wholly Owned Properties
              as of December 31,

              Region

               2007
               2006
               2005
               2007
               2006
               2005
              Baltimore/Washington Corridor 46.2%51.2%47.8%101 87 82
              Northern Virginia 19.4%20.5%21.5%14 14 13
              Suburban Baltimore 14.1%7.5%10.1%64 23 25
              Suburban Maryland 4.3%4.1%5.2%5 5 7
              Colorado Springs 4.0%4.2%1.7%13 11 5
              St. Mary's and King George Counties 3.5%4.2%4.3%18 18 18
              Greater Philadelphia 3.1%3.7%4.0%4 4 4
              San Antonio 2.1%2.4%1.5%2 2 2
              Northern/Central New Jersey 1.0%2.2%3.9%4 6 9
              Other 2.3%N/A N/A 3 N/A N/A
                
               
               
               
               
               
                100.0%100.0%100.0%228 170 165
                
               
               
               
               
               

                      The most significant change in the regional allocation from December 31, 2006 to December 31, 2007 occurred as a result of the Nottingham Acquisition which, due to the large number of properties located in Suburban Baltimore, significantly increased that region's allocation and had a decreasing effect on the other regions, although the resulting decrease in the Baltimore/Washington Corridor was offset slightly by the effects in that region of (1) the properties acquired in that region in the Nottingham Acquisition and (2) newly-constructed properties placed into service in 2007. The most significant changes in the regional allocation from December 31, 2005 to December 31, 2006 occurred as a result of property acquisitions in the Baltimore/Washington Corridor and Colorado Springs and the sale of properties in Suburban Baltimore and Suburban Maryland. It is also noteworthy that our

              46



              allocation in Northern/Central New Jersey has decreased over the last two years due primarily to our sale of properties in that region.

                      As of December 31, 2007, we had construction underway on four wholly owned properties in Colorado Springs, three wholly owned properties in the Baltimore/Washington Corridor and two wholly owned properties in San Antonio; we expect that these properties will be completed and begin generating rental revenue between 2008 and 2009. We also have redevelopment activities underway on one wholly owned property in Colorado Springs that we expect to be completed and to begin generating rental revenue between 2008 and 2009.

                Concentration of Leases With Certain Tenants

                      Our customer strategy focuses on establishing, maintaining and expanding strategic customer relationships in multiple locations. A result of this strategy is that the source of our revenue is highly concentrated with certain tenants. The following schedule lists our 20 largest tenants in our portfolio of wholly owned properties based on percentage of annualized rental revenue:

               
               Percentage of Annualized Rental Revenue of Wholly Owned Properties for 20 Largest Tenants as of December 31,
               
              Tenant

               
               2007
               2006
               2005
               
              United States Government 16.3%16.3%15.2%
              Northrop Grumman Corporation(1) 7.4%4.2%4.5%
              Booz Allen Hamilton, Inc.  5.6%6.9%5.0%
              Computer Sciences Corporation(1) 3.2%3.8%4.1%
              Unisys Corporation(2) 2.5%3.0%3.1%
              L-3 Communications Holdings, Inc.(1) 2.5%3.0%3.4%
              General Dynamics Corporation 2.1%2.4%2.6%
              The Aerospace Corporation 1.9%2.1%2.2%
              Wachovia Corporation(1) 1.9%2.1%2.1%
              Comcast Corporation 1.7%N/A N/A 
              AT&T Corporation(1) 1.7%3.0%2.7%
              The Boeing Company(1) 1.2%1.4%1.6%
              ITT Corporation(1) 1.1%0.8%N/A 
              Ciena Corporation 1.0%1.2%1.3%
              Science Applications International Corporation 0.9%1.1%N/A 
              BAE Systems PLC(1) 0.8%1.0%N/A 
              Johns Hopkins University 0.8%N/A 1.0%
              Merck & Co., Inc.(2) 0.8%0.8%0.9%
              Magellan Health Services, Inc.  0.7%1.0%1.1%
              Wyle Laboratories, Inc.  0.7%0.8%0.9%
              Lockheed Martin Corporation N/A 1.0%1.0%
              Harris Corporation N/A 0.8%N/A 
              VeriSign, Inc.  N/A N/A 1.3%
              PricewaterhouseCoopers LLP N/A N/A 1.0%
              Carefirst, Inc. and Subsidiaries(1) N/A N/A 0.9%
                
               
               
               
              Subtotal of 20 largest tenants 54.8%56.7%55.9%
              All remaining tenants 45.2%43.3%44.1%
                
               
               
               
              Total 100.0%100.0%100.0%
                
               
               
               

                  (1)
                  Includes affiliated organizations and agencies and predecessor companies.

                  (2)
                  Unisys Corporation ("Unisys") subleases space to Merck and Co., Inc. ("Merck"); revenue from this subleased space is classified as Merck revenue.

                      Most of the changes in our tenant concentration over the last two years occurred as a result of development, acquisition and leasing activities. From a development perspective in 2007, we had

              47



              548,614 square feet in newly-constructed properties become operational, of which 295,842 square feet were leased to Northrop Grumman Corporation and 166,179 to the United States Government. From an acquisition perspective in 2007, the Nottingham Acquisition was our only significant acquisition of properties; since none of our 20 largest tenants as of December 31, 2006 had significant leasing positions in the properties acquired in that transaction, the transaction: (1) had a decreasing effect on the level of concentration with those tenants; and (2) led to the addition of Comcast Corporation and Johns Hopkins University as being among our 20 largest tenants.

                      Most of our leases with the United States Government provide for a series of one-year terms or provide for early termination rights. The government may terminate its leases if, among other reasons, the United States Congress fails to provide funding.

                Industry Concentration of Tenants

                      Under our industry strategy, we focus on strategic industries in which tenants have specialized product requirements. A high concentration of our revenues is generated from the United States defense industry (comprised of the United States Government and defense contractors), of which substantially all is associated with defense information technology activities. These tenants are particularly interested in a number of our property markets and submarkets that are located near government installations. We also enable these tenants to benefit from our significant experience in constructing and operating secure properties and properties that meet the United States Government's Force Protection requirements. The table below sets forth the percentage of annualized rental revenue in our portfolio of wholly owned properties derived from that industry:

               
               Percentage of Annualized Rental
              Revenue of Wholly Owned
              Properties from Defense Industry
              Tenants as of December 31,

               
               
               2007
               2006
               2005
               
              Total Portfolio 47.9%54.4%49.7%
              Baltimore/Washington Corridor 65.3%66.7%65.7%
              Northern Virginia 50.3%54.5%50.4%
              Suburban Baltimore 5.3%9.8%6.8%
              Suburban Maryland 11.2%13.3%2.2%
              Colorado Springs 37.8%39.4%74.1%
              St. Mary's and King George Counties 90.0%89.8%90.7%
              San Antonio 100.0%100.0%100.0%

                      With the exception of 2007, the percentage of our annualized rental revenue in our wholly owned properties derived from the United States defense industry has generally increased in recent years due in large part to the continuing expansion trend of the industry in the Greater Washington, D.C. region and, in particular, in our submarkets since the events of September 11, 2001. This percentage did decrease for the total portfolio and in the Suburban Baltimore and Baltimore/Washington Corridor regions in 2007 due primarily to the Nottingham Acquisition, since the properties included in the transaction had an insignificant number of tenants in that industry. This decreasing effect overall and in the Baltimore/Washington Corridor was offset to a certain extent by new leasing in 2007 to tenants in that industry which included, among other things, the effect of the delivery of 166,179 square feet in newly constructed properties in the Baltimore/Washington Corridor. The increase in 2006 for the total portfolio included the effect of certain properties that we acquired or constructed and placed in service in 2006 having leases with the United States Government and defense contractors.

              48


                      We classify the revenue from our leases into industry groupings based solely on our knowledge of the tenants' operations in leased space. Occasionally, classifications require subjective and complex judgments. For example, we have a tenant that is considered by many to be in the computer industry; however, since the nature of that tenant's operations in the space leased from us is focused on providing service to the United States Government's defense department, we classify the revenue we earn from the lease as United States defense industry revenue. We do not use independent sources such as Standard Industrial Classification codes for classifying our revenue into industry groupings and if we did, the resulting groupings would be materially different.

                      In 2007, leases commenced for two newly constructed properties totaling 295,842 square feet that will function as data centers. These properties, when added to a number of data centers already existing in our portfolio, represent a growing concentration in that industry/property type.

              Results of Operations

                      While reviewing this section, you should refer to the tables in the section entitled "Selected Financial Data." You should also refer to the section below entitled "Liquidity and Capital Resources" for certain factors that could negatively affect various aspects of our operations.

                Occupancy and Leasing

                      The table below sets forth leasing information pertaining to our portfolio of wholly owned operating properties:

               
               December 31,
               
               
               2007
               2006
               2005
               
              Occupancy rates at year end          
               Total  92.6% 92.8% 94.0%
               Baltimore/Washington Corridor  92.6% 95.1% 96.2%
               Northern Virginia  98.6% 90.9% 96.4%
               Suburban Baltimore  84.8% 81.1% 84.7%
               Suburban Maryland  97.8% 83.2% 79.8%
               Colorado Springs  96.7% 92.8% 85.8%
               St. Mary's and King George Counties  91.6% 92.1% 95.4%
               Greater Philadelphia  100.0% 100.0% 100.0%
               San Antonio  100.0% 100.0% 100.0%
               Northern/Central New Jersey  70.8% 97.2% 96.4%
               Other  100.0% N/A  N/A 

               
              Renewal rate of square footage for scheduled lease expirations during year(1)  69.1% 55.4% 66.6%

               
              Average contractual annual rental rate per square foot at year end(2) $21.36 $20.90 $20.28 

                  (1)
                  Includes the effects of early renewals and early lease terminations.

                  (2)
                  Includes estimated expense reimbursements.

                      As shown in the above table, the total year end occupancy rate for our portfolio of wholly owned properties did not change significantly from 2006 to 2007. The 2007 year end occupancy was negatively affected by the operating properties included in the Nottingham Acquisition, which were 85.7% occupied at the time the transaction was completed and 86.5% occupied at December 31, 2007. We also had a decrease in occupancy in our Northern/Central New Jersey region that was attributable primarily to a lease termination at our 429 Ridge Road property in Dayton, New Jersey (we sold the 429 Ridge Road property on January 31, 2008). However, we had a net increase in occupancy in our other properties that significantly offset the decreasing effects of the Nottingham Acquisition and the

              49



              429 Ridge Road property. The significant increase in the year end occupancy rate of our Northern Virginia region from 2006 to 2007 was attributable to two large building spaces that had leases commence in early 2007. The significant increase in the year end occupancy rate of our Suburban Maryland region from 2006 to 2007 was due primarily to significant leasing activity in two properties in that region.

                      The decrease in our total year end occupancy rate from 2005 to 2006 for our portfolio of wholly owned properties reflected the adverse impact of the two large building spaces in Northern Virginia discussed above that were vacant at December 31, 2006 and leased in early 2007. The 2006 year end occupancy rates were positively impacted by acquisitions of wholly owned properties completed in 2006, with such properties carrying a weighted average occupancy rate of 95.1% at December 31, 2006.

                      Our renewal rates of square footage for scheduled lease expirations decreased in 2006 but increased in 2007; the 2006 rate in particular was low in comparison to the other calendar years within the 2000 through 2007 timeframe, when the annual renewal rate ranged from 66% to 76% and averaged 70% (when excluding the 2006 calendar year). The 2006 renewal rate was adversely affected by large amounts of space in newly acquired properties that we knew were not going to be renewed when we acquired such properties, including 197,000 square feet in two properties; our renewal rates would have been in the low to mid 60% range without the effect of this space. We believe if we are successful in implementing our customer strategy that we should be able to post renewal rates that approximate our historical average in the future.

                      Our average contractual annual rent per square foot increased 2.2% from December 31, 2006 to December 31, 2007 despite the fact that such rate was negatively affected by the operating properties included in the Nottingham Acquisition, the rate per square foot of which was $16.98 at December 31, 2007, or 21% below our wholly owned portfolio rate. Our average contractual annual rent per square foot increased 3.0% from December 31, 2005 to December 31, 2006 despite the fact that such rate was negatively affected by acquisitions completed during 2006, the rate per square foot of which was $14.12 at December 31, 2006, or 32% below our wholly owned portfolio rate. The year end average contractual rental rate per square foot increased from 2006 to 2007 and from 2005 to 2006 despite being negatively affected by these acquisitions due primarily to the effect of new leases entered into at a higher rate during each of those years and scheduled increases that took place at leases remaining in place. The lower average contractual annual rent per square foot on operating properties included in the Nottingham Acquisition and the acquisitions completed in 2006 can be attributed primarily to the following: (1) lower rents in geographic areas where certain of these acquisitions took place; (2) lower costs for operating expenses and tenant improvements associated with underlying leases in certain of these acquisitions; and (3) lower rents associated with lower grade space in certain of these acquisitions.

                      We believe that there is a fair amount of uncertainty surrounding the outlook for leasing activity for our overall portfolio in 2008 and 2009. Certain national key economic indicators such as employment growth, gross domestic product and housing starts, combined with turmoil in the financial markets brought about in large part in response to the sub-prime mortgage market decline, have caused disruption to the United States economy and capital markets. While we do not believe that the effects of these developments in the economy significantly impacted our 2007 leasing performance, we believe that it could impact our performance in 2008 and 2009, and possibly beyond, as we believe that there is generally a lag in time before economic developments affect the office real estate market. We do believe that our overall portfolio from a leasing and occupancy perspective may not be affected to the same extent as some of our peers in the office real estate industry due in large part to: (1) the quality of our tenant base from a credit risk perspective and our ability to retain such tenants; (2) our concentration of tenants in the United States defense industry, particularly in the area of defense information technology, the need for which we do not believe will diminish in the foreseeable future; and (3) higher than average likelihood for stability in our markets and submarkets due to their proximity to large demand drivers (such as government installations), strong demographics and

              50



              attractiveness to high quality tenants. We believe that reporting by the Base Realignment and Closure Commission of the United States Congress ("BRAC"), which is charged with reallocating personnel between government installations, favors the reallocation of additional personnel to many of the regions in which our properties are located, although there is some uncertainty over the level and timing of such reallocations.

                      We believe that market level occupancy rates in many of our markets may have peaked or started to decline during 2007 from a quarter to quarter trending perspective, although we believe that the occupancy rate in our properties was generally higher than the market level occupancy rate in most of our markets. In our largest geographic region concentration, the Baltimore/Washington Corridor, we are facing a higher level of competition than we have historically due to new firms entering the market with additional new space to a large extent in anticipation of the expansion brought about by the BRAC activities. In our second largest regional concentration, Northern Virginia, market level occupancy rates are trending downwards and speculative construction of additional space in the market is nearing completion and, as a result, could further decrease occupancy rates; however, we believe that we are somewhat protected in the short run in the Northern Virginia region since, with the exception of calendar year 2010 (when 20.6% of our annualized rental revenues at December 31, 2007 from that region were scheduled to expire), no more than 7.0% of the annualized rental revenues at December 31, 2007 from that region were scheduled to expire in any one calendar year between 2008 and 2013. All of our properties in the Greater Philadelphia region are concentrated under three leases with Unisys that expire in June 2009 (although Unisys subleases approximately 20% of this space to Merck), and we believe that Unisys does not intend to renew the majority of the space; we have commenced activities to re-lease this space.

                      We did experience increased delays in 2007 in the leasing of certain projects under construction that were not pre-leased. These delays resulted in the delay of some square footage under construction from becoming operational and also led to our deferral of certain projects under development on which we were about to commence construction. We do believe that we need to continue to commence construction on properties that are not pre-leased to a certain extent in certain of our markets to enable us to meet the demand of tenants that require space meeting their needs in a short timeframe.

                      Despite the continued uncertainty regarding our 2008 leasing outlook, we believe that we are somewhat protected in the short run from a slow down in leasing activity since the weighted average lease term for our wholly owned properties at December 31, 2007 was five years. In addition, only 11.2% of our annualized rental revenues at December 31, 2007 were from leases scheduled to expire by the end of 2008. Looking longer term, 62.2% of our annualized rental revenues on leases in place as of December 31, 2007 were from leases scheduled to expire by the end of 2012, with no more than 15% scheduled to expire in any one calendar year between 2008 and 2012.

                      As noted above, most of the leases with our largest tenant, the United States Government, provide for consecutive one-year terms or provide for early termination rights; all of the leasing statistics set forth above assume that the United States Government will remain in the space that they lease through the end of the respective arrangements, without ending consecutive one-year leases prematurely or exercising early termination rights. We report the statistics in this manner since we manage our leasing activities using these same assumptions and believe these assumptions to be probable. Please refer to the section entitled "Liquidity and Capital Resources" where we further discuss our leases with the United States Government and the underlying risks.

              51


                      The table below sets forth occupancy information pertaining to operating properties in which we have a partial ownership interest:

               
                
               Occupancy Rates at
              December 31,

               
              Geographic Region

               Ownership
              Interest

               
               2007
               2006
               2005
               
              Suburban Maryland 50.0%76.2%47.9%47.9%
              Northern Virginia(1) 92.5%100.0%100.0%100.0%
              Greater Harrisburg 20.0%90.5%91.2%89.4%
              Northern/Central New Jersey(2) 20.0%N/A N/A 80.9%

                  (1)
                  Excludes the effect of 115,866 unoccupied square feet undergoing redevelopment at year end.

                  (2)
                  The property in this geographic region was sold in July 2006.

                Revenues from Real Estate Operations and Property Operating Expenses

                      We typically view our changes in revenues from real estate operations and property operating expenses as being comprised of three main components:

                changes attributable to the operations of properties owned and 100% operational throughout the two years being compared. We define these as changes from "Same-Office Properties." For example, when comparing 2006 and 2007, Same-Office Properties would be properties owned and 100% operational from January 1, 2006 through December 31, 2007. For further discussion of the concept of "operational," you should refer to the section of Note 2 of the Consolidated Financial Statements entitled "Commercial Real Estate Properties;"

                changes attributable to operating properties acquired during the two years being compared and newly-constructed properties that were placed into service and not 100% operational throughout the two years being compared. We define these as changes from "Property Additions;" and

                changes attributable to properties sold during the two years being compared that are not reported as discontinued operations. We define these as changes from "Sold Properties."

                      The tables below set forth the components of our changes in revenues from real estate operations and property operating expenses (dollars in thousands). The tables and the discussion that follows in this section include results and information pertaining to properties included in continuing operations:

               
               Changes from 2006 to 2007
               
                
               Same-Office Properties
                
                
               
               Property
              Additions
              Dollar
              Change(1)

                
                
               
               Dollar
              Change

               Percentage
              Change

               Other
              Dollar
              Change(2)

               Total
              Revenues from real estate operations              
               Rental revenue $56,257 $5,092 2.1%$326 $61,675
               Tenant recoveries and other real estate operations revenue  8,880  4,221 11.9% 595  13,696
                
               
                 
               
                Total $65,137 $9,313 3.4%$921 $75,371
                
               
                 
               
              Property operating expenses $21,488 $6,854 7.8%$2,033 $30,375
                
               
                 
               
              Straight-line rental revenue adjustments included in rental revenue $3,574 $(1,765)N/A $81 $1,890
                
               
                 
               
              Amortization of deferred market rental revenue $28 $372 N/A $ $400
                
               
                 
               
              Number of operating properties included in component category  76  153 N/A    229
                
               
                 
               

              (1)
              Includes 62 acquired properties, 12 newly-constructed properties and two redevelopment properties placed into service.

              (2)
              Includes, among other things, the effects of amounts eliminated in consolidation. Certain amounts eliminated in consolidation are attributable to the Property Additions and Same-Office Properties.

              52


               
               Changes from 2005 to 2006
               
                
               Same-Office Properties
                
                
                
               
               Property
              Additions
              Dollar
              Change(1)

               Sold
              Properties
              Dollar
              Change(2)

                
                
               
               Dollar
              Change

               Percentage
              Change

               Other
              Dollar
              Change(3)

               Total
              Revenues from real estate operations                 
               Rental revenue $51,645 $1,086 0.6%$(5,586)$(1,376)$45,769
               Tenant recoveries and other real estate operations revenue  8,232  2,933 11.4% (1,025) 860  11,000
                
               
                 
               
               
                Total $59,877 $4,019 1.8%$(6,611)$(516)$56,769
                
               
                 
               
               
              Property operating expenses $20,022 $5,025 7.5%$(2,259)$(218)$22,570
                
               
                 
               
               
              Straight-line rental revenue adjustments included in rental revenue $5,194 $(1,824)N/A $(56)$(826)$2,488
                
               
                 
               
               
              Amortization of deferred market rental revenue $1,272 $27 N/A $ $(27)$1,272
                
               
                 
               
               
              Number of operating properties included in component category  53  114 N/A  16  1  184
                
               
                 
               
               

              (1)
              Includes 43 acquired properties and 10 newly-constructed properties.

              (2)
              Includes sold properties that are not reported as discontinued operations.

              (3)
              Includes, among other things, the effects of amounts eliminated in consolidation. Certain amounts eliminated in consolidation are attributable to the Property Additions and Same-Office Properties.

                      As the tables above indicate, our total increase in revenues from real estate operations and property operating expenses from 2006 to 2007 and from 2005 to 2006 was attributable primarily to the Property Additions. The increase from 2005 to 2006 in revenues from real estate operations associated with the Property Additions included the effect of certain of our 2005 acquisitions carrying occupancy rates that were lower than the average occupancy rate of our previously existing properties. Acquisitions in 2005 with particularly low occupancy rates upon acquisition included the following: (1) a 1.1 million square foot portfolio acquired in December 2005 that had an occupancy rate averaging approximately 80% in 2005 and 2006; (2) a 118,000 square foot property acquired in October 2005 that was 58% occupied from the date of its acquisition until December 2006; and (3) a 113,000 square foot property acquired in April 2005 that was 23% occupied from its acquisition until December 2005, when it became 100% operational. We occasionally acquire lower occupancy properties such as these for what we view to be the potential for particularly high rates of return on our investment in these properties if we are successful in stabilizing their operations.

                      With regard to changes in the Same-Office Properties' revenues from real estate operations:

                the increase in rental revenue from 2006 to 2007 included the following:

                an increase of $6.2 million, or 2.6%, in rental revenue from the Same-Office Properties attributable primarily to changes in occupancy and rental rates between the two periods. Included in this increase was a $5.0 million increase attributable to three properties ($3.8 million in two properties in Northern Virginia and $1.2 million in one property in the Baltimore/Washington Corridor) and a $1.8 million decrease attributable to one property in Suburban Baltimore; partially offset by

                a decrease of $1.1 million, or 35.8%, in net revenue from the early termination of leases. To explain further the term net revenue from the early termination of leases, when tenants terminate their lease obligations prior to the end of the agreed lease terms, they typically pay fees to break these obligations. We recognize such fees as revenue and write off against

              53


                    such revenue any (1) deferred rents receivable and (2) deferred revenue and deferred assets that are amortizable into rental revenue associated with the leases; the resulting net amount is the net revenue from the early termination of the leases.

                the increase in rental revenue from 2005 to 2006 included the following:

                an increase of $2.7 million, or 1.4%, in rental revenue from the Same-Office Properties attributable primarily to changes in occupancy and rental rates between the two periods. Of this increase, $1.0 million was from one property in New Jersey; partially offset by

                a decrease of $1.6 million, or 37.5%, in net revenue from the early termination of leases.

                tenant recoveries and other revenue increased from 2006 to 2007 and from 2005 to 2006 due primarily to the increase in property operating expenses described below. While we do have some lease structures under which tenants pay for 100% of properties' operating expenses, our most prevalent lease structure is for tenants to pay for a portion of property operating expenses to the extent that such expenses exceed amounts established in their respective leases that are based on historical expense levels. As a result, while there is an inherent direct relationship between our tenant recoveries and property operating expenses, this relationship does not result in a dollar for dollar increase in tenant recoveries as property operating expenses increase.

                      With regard to changes in the Same-Office Properties' property operating expenses:

                the increase in the Same-Office Properties' property operating expenses from 2006 to 2007 included the following:

                an increase of $2.9 million, or 14.5%, in utilities due primarily to (1) rate increases that we believe are the result of (a) increased oil prices and (b) energy deregulation in Maryland and (2) our assumption of responsibility for payment of utilities at certain properties due to changes in occupancy and lease structure;

                an increase of $1.6 million, or 200.2%, in snow removal due to increased snow and ice in most of our regions in 2007;

                an increase of $936,000, or 5.5%, in real estate taxes reflecting primarily an increase in the assessed value of many of our properties. Included in this amount was an increase of $241,000, or 55.8%, attributable to our Colorado Springs portfolio which had a number of properties with significantly higher assessed values;

                an increase of $795,000, or 17.9%, in heating and air conditioning repairs and maintenance due to an increase in general repair activity and the commencement of new service arrangements at certain properties. The higher labor rates were attributable in part to an inflationary trend but also were due to the increased need for us to employ individuals with specialized skills who command higher rates;

                an increase of $764,000, or 7.8%, in repairs and maintenance labor due primarily to: (1) an increase in labor hours due mostly to the addition of new employees to address staffing needs and increased labor requirements at certain properties with increased occupancy; and (2) higher labor rates resulting from an increase in the underlying costs for labor; and

                an increase of $730,000, or 10.4%, in management fees attributable primarily to an increase in revenue billed by the properties (management fees are generally computed based on a percentage of revenue billed by properties). The increase also was attributable in part to a change in the basis for computing management fees for a number of properties in the portfolio from being based on a percentage of property operating expenses to being based on a percentage of revenue.

              54


                  the increase in the Same-Office Properties' property operating expenses from 2005 to 2006 included the following:

                  an increase of $2.1 million, or 15.1%, in utilities due primarily to the same reasons discussed above for the change from 2006 to 2007;

                  an increase of $1.3 million, or 10.5%, in real estate taxes reflecting primarily an increase in the assessed value of many of our properties;

                  an increase of $675,000, or 9.0%, in repairs and maintenance labor due in large part to higher labor hour rates resulting from an increase in the underlying costs for labor due primarily to the reasons discussed above;

                  an increase of $626,000, or 7.2%, in cleaning expenses due primarily to: (1) increased rates for services at certain of our properties requiring specialized services; and (2) our assumption of responsibility for payment of such costs at certain properties due to changes in occupancy and lease structures;

                  an increase of $545,000, or 25.5%, in grounds maintenance due in large part to increased parking lot maintenance projects undertaken in 2006;

                  an increase of $384,000, or 48.6%, in electrical repair expense, $154,000 of which pertained to one property which had a large repair project take place; and

                  a decrease of $1.5 million, or 70.2%, in snow removal expenses resulting from less snow and ice precipitation in most of our regions in 2006.

                        The $2.0 million increase in property operating expenses from 2006 to 2007 that was not attributable to Property Additions or Same-Office Properties included a $1.3 million increase associated with the former Fort Ritchie United States Army base in Cascade, Washington County, Maryland, of which we acquired 500 acres on October 5, 2006 and 91 acres on November 29, 2007. While we had development activities underway at the Fort Ritchie project in 2007, the $1.3 million in operating expenses was associated with the portions of the project held for future lease or development.

                  Construction Contract and Other Service Revenues and Expenses

                        The table below sets forth changes in our construction contract and other service revenues and expenses (dollars in thousands):

                 
                 Changes from 2006 to 2007
                 Changes from 2005 to 2006
                 
                 
                 Construction
                Contract
                Dollar
                Change

                 Other
                Service
                Operations
                Dollar
                Change

                 Total Dollar
                Change

                 Construction
                Contract
                Dollar
                Change

                 Other
                Service
                Operations
                Dollar
                Change

                 Total Dollar
                Change

                 
                Service operations                   
                 Revenues $(15,108)$(3,751)$(18,859)$(22,175)$3,025 $(19,150)
                 Expenses  (14,238) (3,314) (17,552) (22,573) 2,631  (19,942)
                  
                 
                 
                 
                 
                 
                 
                Income from service operations $(870)$(437)$(1,307)$398 $394 $792 
                  
                 
                 
                 
                 
                 
                 

                        The gross revenues and costs associated with these services generally bear little relationship to the level of activity from these operations since a substantial portion of the costs are subcontracted costs that are reimbursed to us by the customer at no mark up. As a result, the operating margins from these operations are small relative to the revenue. We use the net of service operations revenues and expenses to evaluate performance. Income from service operations decreased from 2006 to 2007 due primarily to: (1) a slow down in activity on certain third party constructions jobs; and (2) a decrease in third party work for heating and air conditioning controls and plumbing services. While we believe that the change in third party construction job activity represents normal fluctuation of activity, the decrease in third party work for heating and air conditioning controls and plumbing services was attributable to our decision in 2007 to limit the amount of these services that we provide to third parties and, instead, focus on providing these services predominantly for our properties. We do not believe that the changes in net amounts from 2005 to 2006 reflected above were significant.

                55


                        Construction contract revenues were significantly higher in 2005 compared to 2007 and 2006 due primarily to a large volume of activity for certain existing contracts in that year. Construction contract revenues were significantly lower in 2007 compared to 2006 due primarily to decreased construction activity on certain third party jobs. It is noteworthy that our revenue from construction contract activity is highly concentrated, with three contracts representing approximately 82% of our 2007 construction contract revenue and five contracts representing approximately 81% of our 2006 construction contract revenue.

                        Other service operations revenue increased 62.0% from 2005 to 2006 but decreased 47.5% from 2006 to 2007. While the increase from 2005 to 2006 was due primarily to a higher volume of work for heating and air conditioning controls and plumbing services, much of which was attributable to one client relationship, the decrease from 2006 to 2007 was attributable to our decision in 2007 discussed above to limit the amount of these services that we provide to third parties.

                  Depreciation and Amortization

                        Our depreciation and other amortization expense from continuing operations increased from 2006 to 2007 by $28.3 million, or 36.2%, due primarily to a $30.4 million increase attributable to the Property Additions. Of the increase attributable to the Property Additions, $22.8 million was attributable to the Nottingham Acquisition. Compared to other acquisitions that we have completed in recent years, a considerably larger portion of the value of the operating properties included in the Nottingham Acquisition was allocated to assets with lives that are based on the lives of the underlying leases; due to that fact and the fact that a large number of the leases in these properties have lives of four years or less, much of the depreciation and amortization associated with these properties is front-loaded to the four years following the completion of the acquisition. This will result in increased depreciation and amortization expense over the initial four years following the acquisition. The net increase in depreciation and other amortization expense from 2006 to 2007 also included a decrease of $2.9 million attributable to one of the Same-Office Properties that had significant depreciation and amortization expense in 2006 associated with a lease that terminated in 2006.

                        Our depreciation and other amortization expense from continuing operations increased from 2005 to 2006 by $17.6 million, or 29.2%, due primarily to a $19.7 million increase attributable to the Property Additions, offset in part by a $1.6 million decrease attributable to the absence of depreciation and amortization in 2006 on the Harrisburg portfolio due to its contribution into an unconsolidated real estate joint venture in September 2005.

                  General and Administrative Expenses

                        General and administrative expenses increased as a percentage of operating income from 14.3% in 2005 to 15.6% in 2006 and to 17.1% in 2007. Much of this trend can be attributed to an increase in the size of our employee base in response to the continued growth of the Company. We expect this trend to continue over the next year and then stabilize as we determine that the Company's employee base and processes are positioned appropriately in anticipation of our future growth expectations.

                        Our general and administrative expense increased from 2006 to 2007 by $3.6 million, or 21.2%, which included the following:

                  a $5.2 million, or 36.6%, increase in compensation expense due in large part to: (1) the increased number of employees in response to the continued growth of the Company; (2) increased salaries and bonuses for existing employees; and (3) a $1.8 million increase in expense associated with share-based compensation due to the effects of awards issued in 2006 and 2007 and an increase in the award values being amortized into expense; and

                  a $1.8 million, or 38.6%, decrease attributable to increased allocation of corporate overhead primarily to our service companies. Although our overall general and administrative expenses

                56


                    increased as discussed above, this $1.8 million decrease in general and administrative expenses was caused by the combined effect of: (1) the increase in allocable general and administrative expenses; and (2) a larger percentage of general and administrative expenses being allocated to the service companies due in large part to the increased number of employees in the service companies.

                        Our general and administrative expense increased from 2005 to 2006 by $3.4 million, or 25.1%, which was attributable primarily to an increase of $2.5 million, or 21.5%, in compensation expense due to: (1) the increased number of employees; (2) increased salaries and bonuses for existing employees; and (3) an increase of $537,000 in expense associated with options issued to employees that was attributable to our adoption of SFAS 123(R) on January 1, 2006.

                  Interest Expense and Amortization of Deferred Financing Costs

                        Our interest expense and amortization of deferred financing costs included in continuing operations increased from 2006 to 2007 by $12.6 million, or 17.2%. This increase included the effects of the following:

                  a 26.1% increase in our average outstanding debt balance resulting primarily from our 2006 and 2007 acquisition and construction activities; offset in part by the effects of

                  an increase in interest capitalized to construction, development and redevelopment projects of $4.7 million, or 32.4%, due to increased construction, development and redevelopment activity; and

                  a decrease in our weighted average interest rates from 6.2% to 5.8%.

                        Our interest expense and amortization of deferred financing costs included in continuing operations increased from 2005 to 2006 by $17.0 million, or 30.2%, from 2005 to 2006. This increase included the effects of the following:

                  a 20.7% increase in our average outstanding debt balance, resulting primarily from our 2005 and 2006 acquisition and construction activities; and

                  an increase in our weighted average interest rates from 5.8% to 6.2%; offset in part by

                  an increase in interest capitalized to construction, development and redevelopment projects of $4.7 million, or 47.5%, due to increased construction, development and redevelopment activity.

                        Interest expense and deferred financing costs as a percentage of net operating income increased from 59.4% in 2005 to 67.4% in 2006 and to 71.3% in 2007 due in large part to a higher proportion of our investing and financing activities having been funded by debt versus equity and the reasons discussed above for the changes in interest expense. We historically have financed our long-term capital needs, including property acquisition and development activities, through a combination of the following:

                  borrowings under our Revolving Credit Facility;

                  borrowings from new debt;

                  issuances of common shares, preferred shares and common units and/or preferred units in our Operating Partnership;

                  contributions from outside investors into real estate joint ventures;

                  proceeds from sales of real estate; and

                  any available residual cash flow from operations.

                        Many factors go into our decisions regarding when to finance investing and financing activities using debt versus equity. We generally use long-term borrowings as attractive financing conditions arise

                57



                and equity issuances as attractive equity market conditions arise. As a result, the change in the proportion of our investing and financing activities funded by debt versus equity described above is not a trend that necessarily should be expected to continue.

                        As of December 31, 2007, 19.1% of our total debt had variable interest rates, including the effect of interest rate swaps. As of December 31, 2007, 88.0% of our fixed-rate debt was scheduled to mature after 2008. For a more comprehensive quantitative analysis of our debt, please refer to the section below entitled "Quantitative and Qualitative Disclosures About Market Risk."

                  Gain on sale of non-real estate investment

                        Included as income for the year ended December 31, 2007 was a $1.0 million gain recognized on the disposition of most of our investment in TractManager, Inc., an investment that we account for using the cost method of accounting. TractManager, Inc. is an entity that developed an Internet-based contract imaging system for sale to real estate owners and healthcare providers.

                  Minority Interests

                        Interests in our Operating Partnership are in the form of preferred and common units. The line entitled "minority interests in income from continuing operations" includes primarily income from continuing operations allocated to preferred and common units not owned by us. Income is allocated to minority interest preferred unitholders in an amount equal to the priority return from the Operating Partnership to which they are entitled. Income is allocated to minority interest common unitholders based on the income earned by the Operating Partnership, after allocation to preferred unitholders, multiplied by the percentage of the common units in the Operating Partnership owned by those common unitholders.

                        As of December 31, 2007, we owned 84.7% of the outstanding common units and 95.8% of the outstanding preferred units. The percentage of the Operating Partnership owned by minority interests during the last three years decreased in the aggregate due primarily to the effect of the following transactions:

                  the issuance of additional units to us as we issued new preferred shares and common shares during 2005 through 2007 due to the fact that we receive preferred units and common units in the Operating Partnership each time we issue preferred shares and common shares; and

                  the exchange of common units for our common shares by certain minority interest holders of common units; offset in part by

                  our issuance of common units to third parties totaling 262,165 in 2007, 181,097 in 2006 and 232,655 in 2005 in connection with acquisitions; and

                  the redemption by us of the Series E and Series F Preferred Shares in 2006.

                        Our income from continuing operations allocated to minority interests decreased by $428,000, or 11.1%, from 2006 to 2007 and by $1.1 million, or 21.9%, from 2005 to 2006. These decreases are due to: (1) a decrease in the income available to allocate to minority interests holders of common units attributable primarily to the reasons set forth above for changes in revenue and expense items combined with the effect of increasing preferred share dividends; and (2) our increasing ownership of common units (from 80.3% at December 31, 2004 to 84.7% at December 31, 2007).

                  Income from discontinued operations, net of minority interests

                        Our income from discontinued operations decreased $16.1 million, or 89.7%, from 2006 to 2007 and increased $11.9 million, or 195.1%, from 2005 to 2006 due primarily to changes in gain from sales of real estate included in discontinued operations. See Note 18 to the Consolidated Financial Statements for a summary of the components of income from discontinued operations.

                58


                  Adjustments to Net Income to Arrive at Net Income Available to Common Shareholders

                        Preferred share dividends increased from 2005 to 2006 and from 2006 to 2007 due to the additional dividends attributable to the Series J Preferred Shares of beneficial interest issued in July 2006 and Series K Preferred Shares issued in January 2007 exceeding the decrease in dividends attributable to the redemption of the Series E and Series F Preferred Shares of beneficial interest ("Series E Preferred Shares" and "Series F Preferred Shares") in 2006.

                        In 2006, we recognized a $3.9 million decrease to net income available to common shareholders pertaining to the original issuance costs incurred on the Series E and Series F Preferred Shares that were redeemed in 2006.

                  Diluted earnings per common share

                        Diluted earnings per common share on net income available to common shareholders decreased 43.5% from 2006 to 2007 and increased 9.5% from 2005 to 2006 due primarily to the effects of the following:

                  changes in net income available to common shareholders, attributable primarily to the reasons set forth above; and

                  a larger number of common shares outstanding due to share issuances from 2005 to 2007.

                Liquidity and Capital Resources

                        In our discussion of liquidity and capital resources set forth below, we describe certain of the risks and uncertainties relating to our business. However, they may not be the only ones that we face.

                  Cash and Cash Equivalents

                        Our cash and cash equivalents balance as of December 31, 2007 totaled $24.6 million, an increase of 211% from the balance as of December 31, 2006. The balance of cash and cash equivalents that we carried as of the end of each of the eight calendar quarters during the two years ended December 31, 2007 ranged from $5.7 million to $24.6 million and averaged $16.0 million. The cash and cash equivalents balances that we carry as of a point in time can vary significantly due in part to the inherent variability of the cash needs of our acquisition and development activities. We maintain sufficient cash and cash equivalents to meet our operating cash requirements and short term investing and financing cash requirements. When we determine that the amount of cash and cash equivalents on hand is more than we need to meet such requirements, we may pay down our Revolving Credit Facility or forgo borrowing under construction loan credit facilities to fund development activities.

                  Operating Activities

                        We generate most of our cash from the operations of our properties. A review of our Consolidated Statements of Operations indicates that over the last three years, approximately 30% to 33% of our revenues from real estate operations (defined as the sum of (1) rental revenue and (2) tenant recoveries and other real estate operations revenue) were used for property operating expenses. Most of the amount by which our revenues from real estate operations exceeded property operating expenses was cash flow; we applied most of this cash flow towards interest expense, scheduled principal amortization on debt, dividends to our shareholders, distributions to minority interest holders of preferred and common units in the Operating Partnership, capital improvements and leasing costs for our operating properties and general and administrative expenses.

                        Our cash flow from operations determined in accordance with GAAP increased $24.6 million, or 21.7%, from 2006 to 2007; this increase is attributable primarily to the additional cash flow from operations generated by our newly-acquired and newly-constructed properties. We expect to continue to use cash flow provided by operations to meet our short-term capital needs, including all property

                59



                operating expenses, general and administrative expenses, interest expense, scheduled principal amortization of debt, dividends and distributions and capital improvements and leasing costs. We do not anticipate borrowing to meet these requirements. Factors that could negatively affect our ability to generate cash flow from operations in the future are discussed in Item 1A of this report entitled "Risk Factors," and include, without limitation, the following:

                  We earn revenue from renting our properties. Our operating costs do not necessarily fluctuate in relation to changes in our rental revenue. This means that our costs will not necessarily decline and may increase even if our revenue declines.

                  For new tenants or upon lease expiration for existing tenants, we generally must make improvements and pay other tenant-related costs for which we may not receive increased rents. We also may make building-related capital improvements for which tenants may not reimburse us.

                  When leases for our properties expire, our tenants may not renew or may renew on terms less favorable to us than the terms of their original leases. If a tenant leaves, we can expect to experience a vacancy for some period of time as well as higher tenant improvement and leasing costs than if a tenant renews. As a result, our financial performance could be adversely affected if we experience a high volume of tenant departures at the end of their lease terms.

                  As discussed earlier, we are dependent on a highly concentrated number of tenants for a large percentage of our revenue. Most of the leases of one of these tenants, the United States Government, provide for a series of one-year terms or provide for early termination rights. Our cash flow from operations would be adversely affected if our larger tenants fail to make rental payments to us, or if the United States Government elects to terminate several of its leases and the affected space cannot be re-leased on satisfactory terms.

                  As discussed earlier, a high concentration of our revenues comes from tenants in the United States defense industry, of which substantially all is associated with defense information technology activities. A reduction in government spending for these defense activities could affect the ability of our tenants in the defense industry to fulfill lease obligations or decrease the likelihood that these tenants will renew their leases. In the case of the United States Government, a reduction in government spending could result in the early termination of leases.

                  Our performance depends on the ability of our tenants to fulfill their lease obligations by paying their rental payments in a timely manner. In addition, as noted above, we rely on a relatively small number of tenants for a large percentage of our revenue from real estate operations. If one of our major tenants or a number of our smaller tenants were to experience financial difficulties, including bankruptcy, insolvency or general downturn of business, there could be an adverse effect on our results of operations and financial condition.

                  We provide construction management services for third-party clients. When providing these services, we usually pay for the costs of construction and subsequently bill our clients for the costs of construction plus a construction management fee. When we provide construction management services, the costs of construction can be substantial. If any of our clients for these services fail to reimburse us for costs incurred under a significant construction management contract, it could have an adverse effect on our results of operations and financial condition.

                  Since our properties are primarily located in the Mid-Atlantic region of the United States, especially in the Greater Washington, D.C. region, and are also typically concentrated in office parks in which we own most of the properties, we do not have a broad geographic distribution of our properties. As a result, a decline in the real estate market or general economic conditions in the Mid-Atlantic region, the Greater Washington, D.C. region or the office parks in which our properties are located could have an adverse effect on our financial position, results of operations and cash flows.

                60


                    The commercial real estate market is highly competitive. We compete for the purchase of commercial properties with many entities, including other publicly traded commercial REITs. Many of our competitors have substantially greater financial resources than we do. If our competitors prevent us from buying properties that we target for acquisition, we may not be able to meet our property acquisition goals. Moreover, numerous commercial properties compete for tenants with our properties. Some of the properties competing with ours may have newer or more desirable locations, or the competing properties' owners may be willing to accept lower rates than are acceptable to us. Competition for property acquisitions or for tenants in properties that we own could have an adverse effect on our financial performance.

                    If short-term interest rates were to increase, the interest payments on our variable-rate debt would increase, although this increase may be reduced to the extent that we have interest rate swap and cap agreements outstanding. If longer-term interest rates were to increase, we may not be able to refinance our existing indebtedness on terms as favorable as the terms of our existing indebtedness and we would pay more for interest expense on new indebtedness that we incur for future property additions.

                    Our portfolio of properties is insured for losses under our property, casualty and umbrella insurance policies through September 2008. These policies include coverage for acts of terrorism. Although we believe that we adequately insure our properties, we are subject to the risk that our insurance may not cover all of the costs to restore properties damaged by a fire or other catastrophic event. In addition, changes in the insurance industry could occur in the future that may increase the cost of insuring our properties and decrease the scope of insurance coverage, either of which could adversely affect our financial position and operating results.

                    As a REIT, we must distribute at least 90% of our annual taxable income (excluding capital gains), which limits the amount of cash we have available for other business purposes, including amounts to fund our growth. Also, it is possible that because of the differences between the time that we actually receive revenue or pay expenses and the period we report those items for distribution purposes, we may have to borrow funds on a short-term basis to meet the 90% distribution requirement. We may also become subject to tax liabilities that adversely affect our operating cash flow.

                    Investing and Financing Activities During the Year Ended December 31, 2007

                          As discussed above, we completed the Nottingham Acquisition on January 9 and 10, 2007. The acquired properties included 56 operating properties totaling approximately 2.4 million square feet and land parcels totaling 187 acres that we believe can support at least 2.0 million developable square feet. We completed the Nottingham Acquisition for an aggregate cost of $366.9 million, which was financed using the following:

                    the issuance of 3,161,000 common shares to the seller at a value of $156.7 million, or $49.57 per share;

                    the issuance of 531,667 Series K Preferred Shares to the seller at a value of $26.6 million, or $50.00 per share;

                    $89.1 million in borrowings under a variable-rate loan bearing interest at LIBOR plus 1.15 to 1.55%, depending on our leverage levels;

                    borrowings assumed under fixed-rate mortgage loans with an aggregate fair value of $38.6 million;

                    $33.7 million in borrowings under our Revolving Credit Facility;

                    $20.1 million in cash from a previous property sale that was released from escrow;

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                      application of a $2.0 million deposit previously paid by us in 2006; and

                      cash reserves for the balance.

                    We issued the Series K Preferred Shares in the Nottingham Acquisition at a value of, and liquidation preference equal to, $50 per share. The Series K Preferred Shares are nonvoting, redeemable for cash at $50 per share at our option on or after January 9, 2017, and are convertible, subject to certain conditions, into common shares on the basis of 0.8163 common shares for each preferred share, in accordance with the terms of the Articles Supplementary describing the Series K Preferred Shares. Holders of the Series K Preferred Shares are entitled to cumulative dividends, payable quarterly (as and if declared by our Board of Trustees). Dividends accrue from the date of issue at the annual rate of $2.80 per share, which is equal to 5.6% of the $50 per share liquidation preference.

                            We also completed the following acquisitions in 2007:

                      the remaining 50% undivided interest in a 132-acre parcel of land located in Colorado Springs on April 6, 2007, that we believe can support approximately 1.9 million developable square feet of office space, for $13.6 million. We financed most of this acquisition by issuing 262,165 common units in the Operating Partnership valued at $12.1 million; and

                      a 56-acre parcel of land located in Aberdeen, Maryland on September 14, 2007, that we believe can support up to 800,000 developable square feet, for $10.5 million. The property is located adjacent to Aberdeen Proving Ground, which is a United States Government installation. We financed most of this acquisition using cash reserves.

                            Activity related to consolidated joint ventures in 2007 included the following:

                      as of December 31, 2006, we owned a 50% interest in Commons Office 6-B, LLC, an entity developing a land parcel in Hanover, Maryland (Hanover, Maryland is located in the Baltimore/Washington Corridor). We acquired the remaining 50% interest in this entity for $1.3 million on May 24, 2007;

                      we completed on June 26, 2007 the formation of Enterprise Campus Developer, LLC ("Enterprise Campus"), an entity in which we own a 90% interest. This entity was created to develop and construct one or more office buildings on land parcels located in College Park, Maryland as part of a separate joint venture called M Square Associates, LLC ("M Square") that was not formed until January 29, 2008 (College Park, Maryland is located in our Suburban Maryland region). At December 31, 2007, development and construction activities were underway in anticipation of Enterprise Campus' impending membership in M Square; and

                      we completed on July 2, 2007 the formation of Arundel Preserve #5, LLC, an entity in which we own a 50% interest. This entity was created to develop and construct one or more office buildings on a land parcel located in Hanover, Maryland.

                            We had five newly-constructed properties totaling 568,433 square feet (three located in the Baltimore/Washington Corridor and two in our Other region) become fully operational in 2007 (68,196 of these square feet were placed into service in 2006). These properties were 96.3% leased, or considered committed to lease, as of December 31, 2007. Costs incurred on these properties through December 31, 2007 totaled $137.2 million, $60.9 million of which was incurred in 2007. We financed the 2007 costs using primarily borrowings from construction loan facilities on three of the properties; borrowings under these facilities in 2007 totaled $50.8 million.

                            At December 31, 2007, we had construction activities underway on 10 office properties totaling 845,605 square feet that were 36.2% leased, or considered committed to lease, including 48,377 square feet already placed in service in a partially operational property. One of these properties is owned through a consolidated joint venture in which we have a 50% interest. Four each of these properties are located in Colorado Springs and the Baltimore/Washington Corridor and two in San Antonio. We

                    62



                    expect to lease 48.7% of the square footage in these properties to tenants in the United States defense industry. Costs incurred on these properties through December 31, 2007 totaled approximately $99.8 million, of which approximately $61.3 million was incurred in 2007. We have a construction loan facility in place totaling $27.0 million to finance the construction of one of these properties; borrowings under this facility totaled $22.5 million at December 31, 2007, $5.6 million of which was borrowed in 2007. The remaining costs incurred in 2007 were funded using primarily borrowings from our Revolving Credit Facility and cash reserves.

                            The table below sets forth the major components of our additions to the line entitled "Total Commercial Real Estate Properties" on our Consolidated Balance Sheet for 2007 (in thousands):

                    Acquisitions $354,972 
                    Construction and development  178,136 
                    Capital improvements on operating properties  27,880 
                    Tenant improvements on operating properties  20,602(1)
                      
                     
                      $581,590 
                      
                     

                    (1)
                    Tenant improvement costs incurred on newly-constructed properties are classified in this table as construction, development and redevelopment.

                            In 2007, we sold four operating properties totaling 128,153 square feet for a total of $17.8 million, resulting in recognized gain of $3.9 million. We also sold three parcels of land in our Suburban Baltimore region totaling 16 acres, developable into approximately 230,000 square feet, for $8.7 million, resulting in a gain of $3.0 million ($1.9 million gain net of taxes). The net proceeds from these sales after transaction costs totaled approximately $22.3 million (excluding the effect of payments for income taxes). We applied these proceeds to our cash operating reserves.

                            On May 17, 2007, we borrowed $150.0 million under a mortgage loan with a 10-year term at a fixed rate of 5.65%. We used $120.5 million of the proceeds from this loan to pay down debt scheduled to mature in September 2007 and the balance to pay down borrowings under our Revolving Credit Facility.

                            On October 1, 2007, we amended and restated the credit agreement on our Revolving Credit Facility with a group of lenders for which KeyBanc Capital Markets and Wachovia Capital Markets, LLC acted as co-lead arrangers, KeyBank National Association acted as administrative agent and Wachovia Bank, National Association acted as syndication agent. The amended and restated credit agreement increased the amount of the lenders' aggregate commitment under the facility from $500.0 million to $600.0 million, which includes a $50.0 million letter of credit subfacility and a $50.0 million swingline facility (same-day draw requests), with a right for us to further increase the lenders' aggregate commitment during the term to a maximum of $800.0 million, subject to certain conditions. Amounts available under the facility are computed based on 65% of our unencumbered asset value, as defined in the agreement. The facility matures on September 30, 2011, and may be extended by one year at our option, subject to certain conditions. The variable interest rate on the facility is based on one of the following, to be selected by us: (1) the LIBOR rate for the interest period designated by us (customarily the 30-day rate) plus 0.75% to 1.25%, as determined by our leverage levels at different points in time; or (2) the greater of (a) the prime rate of the lender then acting as the administrative agent or (b) the Federal Funds Rate, as defined in the agreement, plus 0.50%. Interest is payable at the end of each interest period (as defined in the agreement), and principal outstanding under the facility is payable on the maturity date. The facility also carries a quarterly fee that is based on the unused amount of the facility multiplied by a per annum rate of 0.125% to 0.20%.

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                            On October 23, 2007, we entered into an interest rate swap agreement that fixes the one-month LIBOR base rate at 4.33% on an aggregate notional amount of $50.0 million. This swap agreement became effective on October 23, 2007 and carries a two-year term.

                      Analysis of Cash Flow Associated With Investing and Financing Activities

                            Our net cash flow used in investing activities increased $73.9 million, or 29.1%, from 2006 to 2007. This increase was due primarily to the following:

                      a $70.3 million, or 24.9%, increase in purchases of and additions to commercial real estate due primarily to the completion of the Nottingham Acquisition. After completing the Nottingham Acquisition early in the year, we did not complete any significant operating property acquisitions as we found the market for acquisitions to be extremely competitive in 2007, with potential target properties selling or priced at amounts that exceeded what our rate on return requirements would permit. Our ability to locate and complete acquisitions is dependent on numerous variables and, as a result, is inherently subject to significant fluctuation from period to period; and

                      a $25.0 million, or 53.6%, decrease in proceeds from sales of properties. Since our real estate sales activity is driven by transactions unrelated to our core operations, our proceeds from sales of properties are subject to significant fluctuation from period to period and, therefore, we do not believe that the change described above is necessarily indicative of a trend. While we expect to reduce or eliminate our real estate investments in certain of our non-core markets in the future, we cannot predict when and if these dispositions will occur.

                            Our cash flow provided by financing activities increased $68.9 million, or 50.0%, from 2006 to 2007. This increase was due primarily to the following:

                      a $183.2 million, or 24.0%, decrease in repayments of mortgage and other loans payable due primarily to our use of proceeds from equity offerings in 2006 (2.0 million common shares issued in April 2006 and 3.4 million preferred shares issued in July 2006) and the proceeds from $200.0 million of exchangeable senior notes issued in September 2006; and

                      $64.4 million in cash used to redeem our Series E and Series F Preferred Shares in 2006; offset in part by

                      a $163.6 million, or 95.6%, decrease in proceeds from the 2006 common and preferred share issuances noted above.

                      Off-Balance Sheet Arrangements

                            During 2007, we owned an investment in an unconsolidated joint venture, Harrisburg Corporate Gateway Partners, L.P., for which we accounted using the equity method of accounting. This joint venture was entered into in 2005 to enable us to contribute office properties that were previously wholly owned by us into the joint venture in order to partially dispose of our interest in the properties. We managed the joint venture's property operations and any required construction projects and earned fees for these services in 2007. This joint venture has a two-member management committee that is responsible for making major decisions (as defined in the joint venture agreement), and we control one of the management committee positions.

                            We and our partner receive returns in proportion to our investments in the joint venture. As part of our obligations under the joint venture arrangement, we agreed to indemnify the partnership's lender for 80% of losses under standard nonrecourse loan guarantees (environmental indemnifications and guarantees against fraud and misrepresentation) during the period of time in which we manage the partnership's properties; we do not expect to incur any losses under these loan guarantees.

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                            We have distributions in excess of our investment in this unconsolidated joint venture of $4.2 million at December 31, 2007 due to our not recognizing gain on the contribution of properties into the joint venture; we did not recognize a gain on the contribution since we have contingent obligations, as described above, remaining in effect as long as we continue to manage the joint venture's properties that may exceed our proportionate interest. We recognized a loss on our investment in this joint venture of $224,000 in 2007. We also realized a net cash inflow from this joint venture of $409,000 in 2007. In addition, we earned fees totaling $458,000 from the joint venture in 2007 for construction, asset management and property management services.

                            During 2007, we also owned investments in five joint ventures that we accounted for using the consolidation method of accounting. We use joint ventures such as these from time to time for reasons that include the following: (1) they can provide a facility to access new markets and investment opportunities while enabling us to benefit from the expertise and relationships of our partners; (2) they are an alternative source for raising capital to put towards acquisition or development activities; and (3) they can reduce our exposure to risks associated with a property and its activities. Our consolidated and unconsolidated joint ventures are discussed in Note 5 to our Consolidated Financial Statements, and certain commitments and contingencies related to these joint ventures are discussed in Note 19.

                            We had no other material off-balance sheet arrangements during 2007.

                      Contractual Obligations

                            The following table summarizes our contractual obligations as of December 31, 2007 (in thousands):

                     
                     For the Years Ended December 31,
                      
                    Contractual obligations(1)(2)
                     2008
                     2009 to 2010
                     2011 to 2012
                     Thereafter
                     Total
                    Debt(3) $297,120 $136,676 $513,014 $878,427 $1,825,237
                    Interest on debt(4)  94,724  160,791  115,903  212,397  583,815
                    Acquisitions of properties(5)  11,045      4,000  15,045
                    New construction and development contracts and obligations(6)(7)  71,639        71,639
                    Third-party construction and development contracts(7)(8)  61,941        61,941
                    Capital expenditures for operating properties(7)(9)  26,461        26,461
                    Operating leases(10)  768  851  99    1,718
                    Other purchase obligations(11)  2,350  4,626  4,547  7,473  18,996
                      
                     
                     
                     
                     
                    Total contractual cash obligations $566,048 $302,944 $633,563 $1,102,297 $2,604,852
                      
                     
                     
                     
                     

                    (1)
                    The contractual obligations set forth in this table generally exclude individual contracts that had a value of less than $20,000. Also excluded are contracts associated with the operations of our properties that may be terminated with notice of one month or less, which is the arrangement that applies to most of our property operations contracts.

                    (2)
                    Not included in this section are amounts contingently payable by us to acquire the membership interests of certain real estate joint venture partners. See Note 19 to our Consolidated Financial Statements for further discussion of such amounts.

                    (3)
                    Represents scheduled principal amortization payments and maturities only and therefore excludes a net premium of $605,000. Our loan maturities in 2008 include $40.6 million that we expect to extend until 2009 and approximately $240.9 million that we expect to refinance with a mix of short-

                    65


                      and long-term financing; the balance of the 2008 maturities represent primarily scheduled principal amortization payments that we expect to pay using cash flow from operations. The 2008 scheduled principal payments by quarter are as follows:

                    First Quarter $4.6 million
                    Second Quarter $141.6 million
                    Third Quarter $80.0 million
                    Fourth Quarter $70.9 million
                    (4)
                    Represents interest costs for debt at December 31, 2007 for the terms of such debt. For variable rate debt, the amounts reflected above used December 31, 2007 interest rates on variable rate debt in computing interest costs for the terms of such debt. For construction loan facilities where the interest payments are not payable as incurred but, rather, are added to the balance of the loan during the construction period, the amounts reflected above assumed that such interest costs are paid monthly as incurred.

                    (5)
                    Represents contractual obligations at December 31, 2007 related to: (1) the acquisition of a parcel of land located in Frederick, Maryland; and (2) a potential $4.0 million final payment related to the acquisition of land at the former Fort Ritchie United States Army base in Cascade, Washington County, Maryland (included in the "Thereafter" column). The final payment for the former Fort Ritchie property could be reduced by a range of $750,000 to the full $4.0 million depending on: (a) defined levels of job creation resulting from the future development of the property taking place; and (b) future real estate taxes generated by the property.

                    (6)
                    Represents contractual obligations pertaining to new construction, development and redevelopment activities. We expect to finance these costs primarily using proceeds from our Revolving Credit Facility and construction loans.

                    (7)
                    Because of the long-term nature of certain construction and development contracts, some of these costs will be incurred beyond 2008.

                    (8)
                    Represents contractual obligations pertaining to projects for which we are acting as construction manager on behalf of unrelated parties who are our clients. We expect to be reimbursed in full for these costs by our clients.

                    (9)
                    Represents contractual obligations pertaining to capital expenditures for our operating properties. We expect to finance all of these costs using cash flow from operations.

                    (10)
                    We expect to pay these items using cash flow from operations.

                    (11)
                    Primarily represents contractual obligations pertaining to managed-energy service contracts in place for certain of our operating properties. We expect to pay these items using cash flow from operations.

                            Certain of our debt instruments require that we comply with a number of restrictive financial covenants, including leverage ratio, minimum net worth, minimum fixed charge coverage, minimum debt service and maximum secured indebtedness. As of December 31, 2007, we were in compliance with these financial covenants.

                      Investing and Financing Activities Subsequent to December 31, 2007

                            On January 29, 2008, we completed the formation of M Square Associates, LLC, a consolidated joint venture in which we hold a 45% equity interest. This joint venture will own, develop and manage office properties, approved for up to approximately 750,000 square feet, located in M Square Research Park in College Park, Maryland. This joint venture had construction underway on a 118,107 square foot property within M Square Research Park.

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                            On January 29, 2008, we had a 59,763 square foot property in Colorado Springs that was 100% pre-leased become fully operational.

                            On January 31, 2008, we completed the sale of the 429 Ridge Road property in our Northern/Central New Jersey region for $17.0 million. We used the proceeds from this sale to pay down our Revolving Credit Facility.

                      Other Future Cash Requirements for Investing and Financing Activities

                            As previously discussed, as of December 31, 2007, we had construction activities underway on 10 office properties totaling 845,605 square feet that were 36.2% pre-leased, or considered committed to lease (including one property owned through a consolidated joint venture in which we have a 50% interest). We estimate remaining costs to be incurred will total approximately $62.4 million upon completion of these properties; we expect to incur these costs in 2008 and 2009. We have $4.5 million remaining to be borrowed under a construction loan facility totaling $27.0 million for one of these properties. We expect to fund the remaining portion of these costs using borrowings from new construction loan facilities and our Revolving Credit Facility.

                            As of December 31, 2007, we had development activities underway on 10 new office properties estimated to total 1.1 million square feet. We estimate that costs for these properties will total approximately $239.1 million. As of December 31, 2007, costs incurred on these properties totaled $33.0 million and the balance is expected to be incurred from 2008 through 2010. We expect to fund most of these costs using borrowings from new construction loan facilities.

                            As of December 31, 2007, we had redevelopment activities underway on an aggregate of 546,615 square feet in four properties (three of these properties are owned through a consolidated joint venture in which we own a 92.5% interest). We estimate that remaining costs of the redevelopment activities will total approximately $14.4 million. We expect to fund most of these costs using borrowings from our Revolving Credit Facility.

                            In September 2007, the City of Colorado Springs announced that it had selected us to be the master developer for the 272-acre site known as the Colorado Springs Mixed-Use Business Park, located at the entrance of the Colorado Springs Airport and adjacent to Peterson Air Force Base. We are currently in the process of negotiating the long-term ground lease and development agreement with the City of Colorado Springs regarding the details of this arrangement; we expect that the terms of these agreements will be finalized in 2008. We expect that this business park can support potential development of approximately 3.5 million square feet, including office, retail, industrial and flex space. We anticipate that this project could cost approximately $800.0 million, which we expect to be funded over the next ten to twenty years. As each parcel commences development, we expect to execute long term land leases. For each parcel, we expect to oversee the development, construction, leasing and management and have a leasehold interest in the buildings.

                            During 2008 and beyond, we expect to complete other acquisitions of properties and commence construction and development activities in addition to the ones previously described. We expect to finance these activities, as we have in the past, using mostly a combination of borrowings from new debt, borrowings under our Revolving Credit Facility, proceeds from sales of existing properties and additional equity issuances of common and/or preferred shares or units.

                            We often use our Revolving Credit Facility initially to finance much of our investing and financing activities. We then pay down our Revolving Credit Facility using proceeds from long-term borrowings as attractive financing conditions arise and equity issuances as attractive equity market conditions arise. As described above, amounts available under the facility are computed based on 65% of our unencumbered asset value, as defined in the agreement. As of February 13, 2008, the borrowing capacity under the Revolving Credit Facility was $600.0 million, of which $222.0 million was available.

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                            Factors that could negatively affect our ability to finance our long-term financing and investing needs in the future are discussed in Item 1A of this report entitled "Risk Factors," and include, without limitation, the following:

                      We have in the past operated with slightly higher debt levels than other REITs. Operating with higher debt levels could make it difficult to obtain additional financing when required and could also make us more vulnerable to an economic downturn. Many of our properties have been mortgaged for indebtedness. In addition, we rely on borrowings to fund some or all of the costs of new property acquisitions, construction and development activities and other items.

                      We may not be able to refinance our existing indebtedness.

                      Much of our ability to raise capital through the issuance of preferred shares, common shares or securities that are convertible into our common shares is dependent on the value of our common and preferred shares. As is the case with any publicly-traded securities, certain factors outside of our control could influence the value of our common and preferred shares. These conditions include, but are not limited to: (1) market perception of REITs in general and office REITs in particular; (2) market perception of REITs relative to other investment opportunities; (3) the level of institutional investor interest in our Company; (4) general economic and business conditions; (5) prevailing interest rates; and (6) market perception of our financial condition, performance, dividends and growth potential.

                      We occasionally complete acquisitions of properties in regions where we did not previously own properties. These acquisitions may entail risks in addition to those we face in other acquisitions where we are familiar with the regions, such as the risk that we do not correctly anticipate conditions or trends in a new region and are therefore not able to operate the acquired property profitably.

                      When we develop and construct properties, we assume the risk that actual costs will exceed our budgets, that we will experience construction or development delays and that projected leasing will not occur, any of which could adversely affect our financial performance and our ability to make distributions to our shareholders. In addition, we generally do not obtain construction financing commitments until the development stage of a project is complete and construction is about to commence. We may find that we are unable to obtain financing needed to continue with the construction activities for such projects.

                      We invest in certain entities in which we are not the exclusive investor or principal decision maker. Aside from our inability to unilaterally control the operations of these joint ventures, our investments entail the additional risks that: (1) the other parties to these investments may not fulfill their financial obligations as investors, in which case we may need to fund such parties' share of additional capital requirements; and (2) the other parties to these investments may take actions that are inconsistent with our objectives.

                      Real estate investments can be difficult to sell and convert to cash quickly, especially if market conditions are depressed. Such illiquidity will tend to limit our ability to vary our portfolio of properties promptly in response to changes in economic or other conditions. Moreover, under certain circumstances, the Internal Revenue Code imposes certain penalties on a REIT that sells property held for less than four years. In addition, for certain of our properties that we acquired by issuing units in our Operating Partnership, we are restricted by agreements with the sellers of the properties for a certain period of time from entering into transactions (such as the sale or refinancing of the acquired property) that will result in a taxable gain to the sellers without the sellers' consent. Due to all of these factors, we may be unable to sell a property at an advantageous time to fund our long-term capital needs.

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                        We are subject to various federal, state and local environmental laws. These laws can impose liability on property owners or operators for the costs of removal or remediation of hazardous substances released on a property, even if the property owner was not responsible for the release of the hazardous substances. Costs resulting from environmental liability could be substantial. The presence of hazardous substances on our properties may also adversely affect occupancy and our ability to sell or borrow against those properties. In addition to the costs of government claims under environmental laws, private plaintiffs may bring claims for personal injury or other reasons. Additionally, various laws impose liability for the costs of removal or remediation of hazardous substances at the disposal or treatment facility. Anyone who arranges for the disposal or treatment of hazardous substances at such a facility is potentially liable under such laws. These laws often impose liability on an entity even if the facility was not owned or operated by the entity.

                      Funds From Operations

                              Funds from operations ("FFO") is defined as net income computed using GAAP, excluding gains (or losses) from sales of real estate, plus real estate-related depreciation and amortization, and after adjustments for unconsolidated partnerships and joint ventures. Gains from sales of newly-developed properties less accumulated depreciation, if any, required under GAAP are included in FFO on the basis that development services are the primary revenue generating activity; we believe that inclusion of these development gains is in accordance with the National Association of Real Estate Investment Trusts ("NAREIT") definition of FFO, although others may interpret the definition differently.

                              Accounting for real estate assets using historical cost accounting under GAAP assumes that the value of real estate assets diminishes predictably over time. NAREIT stated in its April 2002 White Paper on Funds from Operations that "since real estate asset values have historically risen or fallen with market conditions, many industry investors have considered presentations of operating results for real estate companies that use historical cost accounting to be insufficient by themselves." As a result, the concept of FFO was created by NAREIT for the REIT industry to "address this problem." We agree with the concept of FFO and believe that FFO is useful to management and investors as a supplemental measure of operating performance because, by excluding gains and losses related to sales of previously depreciated operating real estate properties and excluding real estate-related depreciation and amortization, FFO can help one compare our operating performance between periods. In addition, since most equity REITs provide FFO information to the investment community, we believe that FFO is useful to investors as a supplemental measure for comparing our results to those of other equity REITs. We believe that net income is the most directly comparable GAAP measure to FFO.

                              Since FFO excludes certain items includable in net income, reliance on the measure has limitations; management compensates for these limitations by using the measure simply as a supplemental measure that is weighed in the balance with other GAAP and non GAAP measures. FFO is not necessarily an indication of our cash flow available to fund cash needs. Additionally, it should not be used as an alternative to net income when evaluating our financial performance or to cash flow from operating, investing and financing activities when evaluating our liquidity or ability to make cash distributions or pay debt service. The FFO we present may not be comparable to the FFO presented by other REITs since they may interpret the current NAREIT definition of FFO differently or they may not use the current NAREIT definition of FFO.

                              Basic funds from operations ("Basic FFO") is FFO adjusted to (1) subtract (a) preferred share dividends and (b) issuance costs associated with redeemed preferred shares and (2) add back GAAP net income allocated to common units in the Operating Partnership not owned by us. With these adjustments, Basic FFO represents FFO available to common shareholders and common unitholders. Common units in the Operating Partnership are substantially similar to our common shares and are exchangeable into common shares, subject to certain conditions. We believe that Basic FFO is useful to

                      69



                      investors due to the close correlation of common units to common shares. We believe that net income is the most directly comparable GAAP measure to Basic FFO. Basic FFO has essentially the same limitations as FFO; management compensates for these limitations in essentially the same manner as described above for FFO.

                              Diluted funds from operations ("Diluted FFO") is Basic FFO adjusted to add back any changes in Basic FFO that would result from the assumed conversion of securities that are convertible or exchangeable into common shares. However, the computation of Diluted FFO does not assume conversion of securities other than common units in the Operating Partnership that are convertible into common shares if the conversion of those securities would increase Diluted FFO per share in a given period. We believe that Diluted FFO is useful to investors because it is the numerator used to compute Diluted FFO per share, discussed below. In addition, since most equity REITs provide Diluted FFO information to the investment community, we believe Diluted FFO is a useful supplemental measure for comparing us to other equity REITs. We believe that the numerator for diluted EPS is the most directly comparable GAAP measure to Diluted FFO. Since Diluted FFO excludes certain items includable in the numerator to diluted EPS, reliance on the measure has limitations; management compensates for these limitations by using the measure simply as a supplemental measure that is weighed in the balance with other GAAP and non-GAAP measures. Diluted FFO is not necessarily an indication of our cash flow available to fund cash needs. Additionally, it should not be used as an alternative to net income when evaluating our financial performance or to cash flow from operating, investing and financing activities when evaluating our liquidity or ability to make cash distributions or pay debt service. The Diluted FFO that we present may not be comparable to the Diluted FFO presented by other REITs.

                              Diluted funds from operations per share ("Diluted FFO per share") is (1) Diluted FFO divided by (2) the sum of the (a) weighted average common shares outstanding during a period, (b) weighted average common units outstanding during a period and (c) weighted average number of potential additional common shares that would have been outstanding during a period if other securities that are convertible or exchangeable into common shares were converted or exchanged. However, the computation of Diluted FFO per share does not assume conversion of securities other than common units in the Operating Partnership that are convertible into common shares if the conversion of those securities would increase Diluted FFO per share in a given period. We believe that Diluted FFO per share is useful to investors because it provides investors with a further context for evaluating our FFO results in the same manner that investors use earnings per share ("EPS") in evaluating net income available to common shareholders. In addition, since most equity REITs provide Diluted FFO per share information to the investment community, we believe Diluted FFO per share is a useful supplemental measure for comparing us to other equity REITs. We believe that diluted EPS is the most directly comparable GAAP measure to Diluted FFO per share. Diluted FFO per share has most of the same limitations as Diluted FFO (described above); management compensates for these limitations in essentially the same manner as described above for Diluted FFO.

                              Our Basic FFO, Diluted FFO and Diluted FFO per share for 2003 through 2007 and reconciliations of (1) net income to FFO, (2) the numerator for diluted EPS to diluted FFO and

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                      (3) the denominator for diluted EPS to the denominator for diluted FFO per share are set forth in the following table (dollars and shares in thousands, except per share data):

                       
                       For the Years Ended December 31,
                      (in thousands, except per share data)

                       
                       
                       2007
                       2006
                       2005
                       2004
                       2003
                       
                      Net income $34,784 $49,227 $39,031 $37,032 $30,877 
                      Add: Real estate-related depreciation and amortization  106,260  78,631  62,850  51,371  36,681 
                      Add: Depreciation and amortization on unconsolidated real estate entities  666  910  182  106  295 
                      Less: Depreciation and amortization allocable to minority interests in other consolidated entities  (188) (163) (114) (86)  
                      Less: Gain on sales of real estate, net of taxes, excluding development portion(1)  (3,827) (17,644) (4,422) (95) (2,897)
                        
                       
                       
                       
                       
                       
                      Funds from operations ("FFO")  137,695  110,961  97,527  88,328  64,956 
                      Add: Minority interests-common units in the Operating Partnership  3,682  7,276  5,889  5,659  6,712 
                      Less: Preferred share dividends  (16,068) (15,404) (14,615) (16,329) (12,003)
                      Less: Issuance costs associated with redeemed preferred shares    (3,896)   (1,813)  
                        
                       
                       
                       
                       
                       
                      Funds from Operations—basic ("Basic FFO")  125,309  98,937  88,801  75,845  59,665 
                      Add: Preferred unit distributions          1,049 
                      Add: Expense on dilutive share-based compensation        382  10 
                      Add: Convertible preferred share dividends        21  544 
                        
                       
                       
                       
                       
                       
                      Funds from Operations—diluted ("Diluted FFO") $125,309 $98,937 $88,801 $76,248 $61,268 
                        
                       
                       
                       
                       
                       
                      Weighted average common shares  46,527  41,463  37,371  33,173  26,659 
                      Conversion of weighted average common units  8,296  8,511  8,702  8,726  8,932 
                        
                       
                       
                       
                       
                       
                      Weighted average common shares/units—Basic FFO  54,823  49,974  46,073  41,899  35,591 
                      Dilutive effect of share-based compensation awards  1,103  1,799  1,626  1,896  1,405 
                      Assumed conversion of weighted average convertible preferred units          1,101 
                      Assumed conversion of weighted average convertible preferred shares        134  1,197 
                        
                       
                       
                       
                       
                       
                      Weighted average common shares/units—Diluted FFO  55,926  51,773  47,699  43,929  39,294 
                        
                       
                       
                       
                       
                       
                      Diluted FFO per common share $2.24 $1.91 $1.86 $1.74 $1.56 
                        
                       
                       
                       
                       
                       
                      Numerator for diluted EPS $18,716 $29,927 $24,416 $18,911 $7,650 
                      Add: Minority interests-common units in the Operating Partnership  3,682  7,276  5,889  5,659  6,712 
                      Add: Real estate-related depreciation and amortization  106,260  78,631  62,850  51,371  36,681 
                      Add: Depreciation and amortization on unconsolidated real estate entities  666  910  182  106  295 
                      Less: Depreciation and amortization allocable to minority interests in other consolidated entities  (188) (163) (114) (86)  
                      Less: Gain on sales of real estate, net of taxes, excluding development portion(1)  (3,827) (17,644) (4,422) (95) (2,897)
                      Add: Convertible preferred share dividends          544 
                      Add: Preferred unit distributions          1,049 
                      Add: Expense on dilutive share-based compensation        382  10 
                      Add: Repurchase of Series C Preferred Units in excess of recorded book value          11,224 
                        
                       
                       
                       
                       
                       
                      Diluted FFO $125,309 $98,937 $88,801 $76,248 $61,268 
                        
                       
                       
                       
                       
                       
                      Denominator for diluted EPS  47,630  43,262  38,997  34,982  28,021 
                      Weighted average common units  8,296  8,511  8,702  8,726  8,932 
                      Assumed conversion of weighted average convertible preferred shares          1,197 
                      Assumed conversion of weighted average convertible preferred units          1,101 
                      Dilutive effect of share-based compensation awards        221  43 
                        
                       
                       
                       
                       
                       
                      Denominator for Diluted FFO per share  55,926  51,773  47,699  43,929  39,294 
                        
                       
                       
                       
                       
                       

                      (1)
                      Gains from the sale of real estate, net of taxes, that are attributable to sales of non-operating properties are included in FFO. Gains from newly-developed or re-developed properties less accumulated depreciation, if any, required under GAAP are also included in FFO on the basis that development services are the primary revenue generating activity; we believe that inclusion of these development gains is in compliance with the NAREIT definition of FFO, although others may interpret the definition differently.

                      71


                      Inflation

                              Most of our tenants are obligated to pay their share of a building's operating expenses to the extent such expenses exceed amounts established in their leases, based on historical expense levels. Some of our tenants are obligated to pay their full share of a building's operating expenses. These arrangements somewhat reduce our exposure to increases in such costs resulting from inflation. In addition, since our average lease life is approximately five years, we generally expect to be able to compensate for increased operating expenses through increased rental rates upon lease renewal or expiration.

                              Our costs associated with constructing buildings and completing renovation and tenant improvement work increased due to higher cost of materials. We expect to recover a portion of these costs through higher tenant rents and reimbursements for tenant improvements. The additional costs that we do not recover increase depreciation expense as projects are completed and placed into service.

                      Recent Accounting Pronouncements

                              For disclosure regarding recent accounting pronouncements and the anticipated impact they will have on our operations, you should refer to Note 2 to our Consolidated Financial Statements.

                      Item 7A.    Quantitative and Qualitative Disclosures about Market Risk

                              We are exposed to certain market risks, the most predominant of which is change in interest rates. Increases in interest rates can result in increased interest expense under our Revolving Credit Facility and our other debt carrying variable interest rate terms. Increases in interest rates can also result in increased interest expense when our debt carrying fixed interest rate terms mature and need to be refinanced. Our financing policy monitors the relationship of our total variable rate debt to our total debt to minimize the risk of short-term increases in interest rates. As of December 31, 2007, 88.0% of our fixed-rate debt was scheduled to mature after 2008. As of December 31, 2007, 19.1% of our total debt had variable interest rates, including the effect of interest rate swaps. As of December 31, 2007, the percentage of variable-rate debt, including the effect of interest rate swaps, relative to total assets was 11.9%.

                              The following table sets forth our long-term debt obligations by scheduled maturity and weighted average interest rates at December 31, 2007 (dollars in thousands):

                       
                       For the Years Ended December 31,
                        
                       
                       
                       2008
                       2009
                       2010
                       2011
                       2012
                       Thereafter
                       Total
                       
                      Long term debt:                      
                      Fixed rate(1) $158,531 $62,643 $74,033 $109,814 $42,200 $878,427 $1,325,648 
                      Average interest rate  5.49% 5.32% 5.26% 5.23% 5.20% 4.21% 4.72%
                      Variable rate $138,589 $ $ $361,000 $ $ $499,589 
                      Average interest rate(2)  6.00% 5.89% 5.89% 5.89%     5.92%

                      (1)
                      Represents principal maturities only and therefore excludes net premiums of $605,000.

                      (2)
                      Computed based on interest rates in effect at December 31, 2007.

                              The fair market value of our debt was $1.83 billion at December 31, 2007 and $1.50 billion at December 31, 2006. If interest rates on our fixed-rate debt had been 1% lower, the fair value of this debt would have increased by $53.7 million at December 31, 2007 and $48.4 million at December 31, 2006.

                      72


                              We occasionally use derivative instruments such as interest rate swaps to further reduce our exposure to changes in interest rates. The following table sets forth information pertaining to our derivative contracts in place as of December 31, 2007 and 2006, and their respective fair values (dollars in thousands):

                       
                        
                        
                        
                        
                       Fair Value at
                      December 31,

                       
                       
                       Notional
                      Amount

                       One-Month
                      LIBOR base

                       Effective
                      Date

                       Expiration
                      Date

                       
                      Nature of Derivative
                       2007
                       2006
                       
                      Interest rate swap $50,000 5.0360%3/28/2006 3/30/2009 $(765)$(42)
                      Interest rate swap  25,000 5.2320%5/1/2006 5/1/2009  (486) (133)
                      Interest rate swap  25,000 5.2320%5/1/2006 5/1/2009  (486) (133)
                      Interest rate swap  50,000 4.3300%10/23/2007 10/23/2009  (596) N/A 
                                 
                       
                       
                                 $(2,333)$(308)
                                 
                       
                       

                              Based on our variable-rate debt balances, our interest expense would have increased by $3.0 million in 2007 and $3.2 million in 2006 if short-term interest rates were 1% higher. Interest expense in 2007 was less sensitive to a change in interest rates than 2006 due primarily to our having a lower average variable-rate debt balance in 2007.

                      Item 8.    Financial Statements and Supplementary Data

                              The response to this item is included in a separate section at the end of this report beginning on page F-1.

                      Item 9.    Changes in and Disagreements with Accountants on Accounting and Financial Disclosure

                              None.

                      Item 9A.    Controls and Procedures

                      I.
                      Disclosure Controls and Procedures

                              Our management, with the participation of our Chief Executive Officer and Chief Financial Officer, evaluated the effectiveness of our disclosure controls and procedures (as defined in Rule 13a-15(e) under the Exchange Act) as of December 31, 2007. Based on this evaluation, our Chief Executive Officer and Chief Financial Officer concluded that our disclosure controls and procedures as of December 31, 2007 are functioning effectively to provide reasonable assurance that the information required to be disclosed by us in reports filed or submitted under the Securities Exchange Act of 1934 is (i) recorded, processed, summarized and reported within the time periods specified in the SEC's rules and forms, and (ii) accumulated and communicated to our management, including our principal executive and principal financial officers, or persons performing similar functions, as appropriate to allow timely decisions regarding required disclosure.

                              A controls system, no matter how well designed and operated, cannot provide absolute assurance that the objectives of the controls system are met, and no evaluation of controls can provide absolute assurance that all control issues and instances of fraud, if any, within a company have been detected.

                      II.
                      Internal Control Over Financial Reporting

                      (a)
                      Management's Annual Report on Internal Control Over Financial Reporting

                              Management's Annual Report on Internal Control Over Financial Reporting is included in a separate section at the end of this report on page F-2.

                      (b)
                      Report of Independent Registered Public Accounting Firm

                              The Report of Independent Registered Public Accounting Firm is included in a separate section at the end of this report on page F-3.

                      (c)
                      Change in Internal Control over Financial Reporting

                              No change in our internal control over financial reporting occurred during the most recent fiscal quarter that has materially affected, or is reasonably likely to materially affect, our internal control over financial reporting.

                      73


                      Item 9B.    Other Information

                              None.


                      PART III

                              Items 10, 11, 12, 13 & 14. Directors, Executive Officers and Corporate Governance; Executive Compensation; Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters; Certain Relationships and Related Transactions, and Director Independence; and Principal Accountant Fees and Services

                              For the information required by Item 10, Item 11, Item 12, Item 13 and Item 14, you should refer to our definitive proxy statement relating to the 2008 Annual Meeting of our Shareholders to be filed with the Securities and Exchange Commission no later than 120 days after the end of the fiscal year covered by this Form 10-K.


                      PART IV

                      Item 15.    Exhibits and Financial Statement Schedules

                        (a)
                        The following documents are filed as exhibits to this Form 10-K:

                        1.
                        Financial Statements. See "Index to Consolidated Financial Statements" on page F-1 of this Form 10-K.

                        2.
                        Financial Statement Schedule. See "Index to Consolidated Financial Statements" on page F-1 of this Form 10-K.

                        3.
                        See section below entitled "Exhibits."

                              (b)  Exhibits. Refer to the Exhibit Index that follows. Unless otherwise noted, the file number of all documents incorporated by reference is 1-14023.

                      EXHIBIT NO.
                       DESCRIPTION
                        
                      3.1.1 Amended and Restated Declaration of Trust of Registrant (filed with the Registrant's Registration Statement on Form S-4 (Commission File No. 333-45649) and incorporated herein by reference).  

                      3.1.2

                       

                      Articles of Amendment of Amended and Restated Declaration of Trust (filed on March 22, 2002 with the Company's Annual Report on Form 10-K for the year ended December 31, 2001 and incorporated herein by reference).

                       

                       

                      3.1.3

                       

                      Articles of Amendment of Amended and Restated Declaration of Trust (filed with the Company's Current Report on Form 8-K on December 29, 2004 and incorporated herein by reference).

                       

                       

                      3.1.4

                       

                      Articles Supplementary of Corporate Office Properties Trust Series B Convertible Preferred Shares, dated July 2, 1999 (filed with the Company's Current Report on Form 8-K on July 7, 1999 and incorporated herein by reference).

                       

                       

                      3.1.5

                       

                      Articles Supplementary of Corporate Office Properties Trust (filed with the Company's Current Report on Form 8-K on December 29, 2004 and incorporated herein by reference).

                       

                       

                      3.1.6

                       

                      Articles Supplementary of Corporate Office Properties Trust (filed with the Company's Current Report on Form 8-K on December 29, 2004 and incorporated herein by reference).

                       

                       

                      74



                      3.1.7

                       

                      Articles Supplementary of Corporate Office Properties Trust relating to the Series E Cumulative Redeemable Preferred Shares, dated April 3, 2001 (filed with the Registrant's Current Report on Form 8-K on April 4, 2001 and incorporated herein by reference).

                       

                       

                      3.1.8

                       

                      Articles Supplementary of Corporate Office Properties Trust relating to the Series F Cumulative Redeemable Preferred Shares, dated September 13, 2001 (filed with the Registrant's Amended Current Report on Form 8-K on September 14, 2001 and incorporated herein by reference).

                       

                       

                      3.1.9

                       

                      Articles Supplementary of Corporate Office Properties Trust relating to the Series G Cumulative Redeemable Preferred Shares, dated August 6, 2003 (filed with the Registrant's Registration Statement on Form 8-A on August 7, 2003 and incorporated herein by reference).

                       

                       

                      3.1.10

                       

                      Articles Supplementary of Corporate Office Properties Trust relating to the Series H Cumulative Redeemable Preferred Shares, dated December 11, 2003 (filed with the Current Report on Form 8-K on December 12, 2003 and incorporated herein by reference).

                       

                       

                      3.1.11

                       

                      Articles Supplementary of Corporate Office Properties Trust relating to the Series J Cumulative Redeemable Preferred Shares of Beneficial Interest (filed with the Company's Current Report on Form 8-K dated July 19, 2006 and incorporated herein by reference).

                       

                       

                      3.1.12

                       

                      Articles Supplementary of Corporate Office Properties Trust relating to the Series K Cumulative Redeemable Convertible Preferred Shares of Beneficial Interest (filed with the Company's Current Report on Form 8-K dated January 16, 2007 and incorporated herein by reference).

                       

                       

                      3.2.1

                       

                      Bylaws of the Registrant (filed with the Registrant's Registration Statement on Form S-4 (Commission File No. 333-45649) and incorporated herein by reference).

                       

                       

                      3.2.2

                       

                      Amendment to Bylaws of the Registrant (filed with the Company's Current Report on Form 8-K on March 7, 2007 and incorporated herein by reference).

                       

                       

                      3.3

                       

                      Form of certificate for the Registrant's Common Shares of Beneficial Interest, $0.01 par value per share (filed with the Registrant's Registration Statement on Form S-4 (Commission File No. 333-45649) and incorporated herein by reference).

                       

                       

                      3.4

                       

                      Amended and Restated Registration Rights Agreement, dated March 16, 1998, for the benefit of certain shareholders of the Company (filed on August 12, 1998 with the Company's Quarterly Report on Form 10-Q for the quarter ended June 30, 1998 and incorporated herein by reference).

                       

                       

                      3.5

                       

                      Registration Rights Agreement, dated January 25, 2001, for the benefit of Barony Trust Limited (filed on March 22, 2001 with the Company's Annual Report on Form 10-K for the year ended December 31, 2000 and incorporated herein by reference).

                       

                       

                      75



                      3.6

                       

                      Registration Rights Agreement, dated September 18, 2006, among Corporate Office Properties, L.P., Corporate Office Properties Trust, Banc of America Securities LLC and J.P. Morgan Securities Inc. (filed with the Company's Current Report on Form 8-K dated September 22, 2006 and incorporated herein by reference).

                       

                       

                      4.1

                       

                      Indenture, dated as of September 18, 2006, among Corporate Office Properties, L.P., as issuer, Corporate Office Properties Trust, as guarantor, and Wells Fargo Bank, National Association, as trustee (filed with the Company's Current Report on Form 8-K dated September 22, 2006 and incorporated herein by reference).

                       

                       

                      4.2

                       

                      3.50% Exchangeable Senior Note due 2026 of Corporate Office Properties, L.P. (filed with the Company's Current Report on Form 8-K dated September 22, 2006 and incorporated herein by reference).

                       

                       

                      10.1.1

                       

                      Second Amended and Restated Limited Partnership Agreement of the Operating Partnership, dated December 7, 1999 (filed on March 16, 2000 with the Company's Annual Report on Form 10-K for the year ended December 31, 1999 and incorporated herein by reference).

                       

                       

                      10.1.2

                       

                      First Amendment to Second Amended and Restated Limited Partnership Agreement of the Operating Partnership, dated December 21, 1999 (filed on March 16, 2000 with the Company's Annual Report on Form 10-K for the year ended December 31, 1999 and incorporated herein by reference).

                       

                       

                      10.1.3

                       

                      Second Amendment to Second Amended and Restated Limited Partnership Agreement of the Operating Partnership, dated December 21, 1999 (filed with the Company's Post Effective Amendment No. 2 to Form S-3 dated November 1, 2000 (Registration Statement No. 333-71807) and incorporated herein by reference).

                       

                       

                      10.1.4

                       

                      Third Amendment to Second Amended and Restated Limited Partnership Agreement of the Operating Partnership, dated September 29, 2000 (filed with the Company's Post Effective Amendment No. 2 to Form S-3 dated November 1, 2000 (Registration Statement No. 333-71807) and incorporated herein by reference).

                       

                       

                      10.1.5

                       

                      Fourth Amendment to Second Amended and Restated Limited Partnership Agreement of the Operating Partnership, dated November 27, 2000 (filed on March 27, 2003 with the Company's Annual Report on Form 10-K for the year ended December 31, 2002 and incorporated herein by reference).

                       

                       

                      10.1.6

                       

                      Fifth Amendment to Second Amended and Restated Limited Partnership Agreement of the Operating Partnership, dated January 25, 2001 (filed on March 27, 2003 with the Company's Annual Report on Form 10-K for the year ended December 31, 2002 and incorporated herein by reference).

                       

                       

                      10.1.7

                       

                      Sixth Amendment to Second Amended and Restated Limited Partnership Agreement of the Operating Partnership, dated April 3, 2001 (filed with the Company's Current Report on Form 8-K dated April 4, 2001 and incorporated herein by reference).

                       

                       

                      76



                      10.1.8

                       

                      Seventh Amendment to Second Amended and Restated Limited Partnership Agreement of the Operating Partnership, dated August 30, 2001 (filed on March 27, 2003 with the Company's Annual Report on Form 10-K for the year ended December 31, 2002 and incorporated herein by reference).

                       

                       

                      10.1.9

                       

                      Eighth Amendment to Second Amended and Restated Limited Partnership Agreement of the Operating Partnership, dated September 14, 2001 (filed with the Company's Amended Current Report on Form 8-K dated September 14, 2001 and incorporated herein by reference).

                       

                       

                      10.1.10

                       

                      Ninth Amendment to Second Amended and Restated Limited Partnership Agreement of the Operating Partnership, dated October 6, 2001 (filed on March 27, 2003 with the Company's Annual Report on Form 10-K for the year ended December 31, 2002 and incorporated herein by reference).

                       

                       

                      10.1.11

                       

                      Tenth Amendment to Second Amended and Restated Limited Partnership Agreement of the Operating Partnership, dated December 29, 2001 (filed on March 27, 2003 with the Company's Annual Report on Form 10-K for the year ended December 31, 2002 and incorporated herein by reference).

                       

                       

                      10.1.12

                       

                      Eleventh Amendment to Second Amended and Restated Limited Partnership Agreement of the Operating Partnership, dated December 15, 2002 (filed on March 27, 2003 with the Company's Annual Report on Form 10-K for the year ended December 31, 2002 and incorporated herein by reference).

                       

                       

                      10.1.13

                       

                      Twelfth Amendment to Second Amended and Restated Limited Partnership Agreement of Corporate Office Properties, L.P., dated June 2, 2003 (filed on August 12, 2003 with the Registrant's Quarterly Report on Form 10-Q for the quarter ended June 30, 2003 and incorporated herein by reference).

                       

                       

                      10.1.14

                       

                      Thirteenth Amendment to Second Amended and Restated Limited Partnership Agreement of Corporate Office Properties, L.P., dated August 11, 2003 (filed on March 27, 2003 with the Company's Annual Report on Form 10-K for the year ended December 31, 2002 and incorporated herein by reference).

                       

                       

                      10.1.15

                       

                      Fourteenth Amendment to Second Amended and Restated Limited Partnership Agreement of Corporate Office Properties, L.P., dated December 18, 2003 (filed on March 11, 2004 with the Company's Annual Report on Form 10-K for the year ended December 31, 2003 and incorporated herein by reference).

                       

                       

                      10.1.16

                       

                      Fifteenth Amendment to Second Amended and Restated Limited Partnership Agreement of Corporate Office Properties, L.P., dated January 31, 2004 (filed on March 11, 2004 with the Company's Annual Report on Form 10-K for the year ended December 31, 2003 and incorporated herein by reference).

                       

                       

                      10.1.17

                       

                      Sixteenth Amendment to Second Amended and Restated Limited Partnership Agreement of Corporate Office Properties, L.P., dated April 15, 2004 (filed on May 7, 2004 with the Company's Form 10-Q for the quarter ended March 31, 2004 and incorporated herein by reference).

                       

                       

                      10.1.18

                       

                      Seventeenth Amendment to Second Amended and Restated Limited Partnership Agreement of Corporate Office Properties, L.P., dated September 23, 2004 (filed with the Company's Current Report on Form 8-K dated September 23, 2004 and incorporated herein by reference).

                       

                       

                      77



                      10.1.19

                       

                      Eighteenth Amendment to Second Amended and Restated Limited Partnership Agreement of Corporate Office Properties, L.P., dated April 18, 2005 (filed with the Company's Form 8-K on April 22, 2005 and incorporated herein by reference).

                       

                       

                      10.1.20

                       

                      Nineteenth Amendment to Second Amended and Restated Limited Partnership Agreement of Corporate Office Properties, L.P., dated July 8, 2005 (filed with the Company's Current Report on Form 8-K on July 14, 2005 and incorporated herein by reference).

                       

                       

                      10.1.21

                       

                      Twentieth Amendment to Second Amended and Restated Limited Partnership Agreement of Corporate Office Properties, L.P., dated June 29, 2006 (filed with the Company's Current Report on Form 8-K dated July 6, 2006 and incorporated herein by reference).

                       

                       

                      10.1.22

                       

                      Twenty-First Amendment to Second Amended and Restated Limited Partnership Agreement of Corporate Office Properties, L.P., dated July 20, 2006 (filed with the Company's Current Report on Form 8-K dated July 26, 2006 and incorporated herein by reference).

                       

                       

                      10.1.23

                       

                      Twenty-Second Amendment to Second Amended and Restated Limited Partnership Agreement of Corporate Office Properties, L.P., dated January 9, 2007 (filed with the Company's Current Report on Form 8-K dated January 16, 2007 and incorporated herein by reference).

                       

                       

                      10.1.24

                       

                      Twenty-Third Amendment to Second Amended and Restated Limited Partnership Agreement of Corporate Office Properties, L.P., dated April 6, 2007 (filed with the Company's Current Report on Form 8-K dated April 12, 2007 and incorporated herein by reference).

                       

                       

                      10.1.25

                       

                      Twenty-Fourth Amendment to Second Amended and Restated Limited Partnership Agreement of Corporate Office Properties, L.P., dated November 2, 2007 (filed with the Company's Current Report on Form 8-K dated November 5, 2007 and incorporated herein by reference).

                       

                       

                      10.2

                       

                      Stock Option Plan for Directors (filed with Royale Investments, Inc.'s Form 10-KSB for the year ended December 31, 1993 (Commission File No. 0-20047) and incorporated herein by reference).

                       

                       

                      10.3.1*

                       

                      Corporate Office Properties Trust 1998 Long Term Incentive Plan (filed with the Registrant's Registration Statement on Form S-4 (Commission File No. 333-45649) and incorporated herein by reference).

                       

                       

                      10.3.2*

                       

                      Amendment No. 1 to Corporate Office Properties Trust 1998 Long Term Incentive Plan (filed on August 13, 1999 with the Company's Quarterly Report on Form 10-Q for the quarter ended June 30, 1999 and incorporated herein by reference).

                       

                       

                      10.3.3*

                       

                      Amendment No. 2 to Corporate Office Properties Trust 1998 Long Term Incentive Plan (filed on March 22, 2002 with the Company's Annual Report on Form 10-K for the year ended December 31, 2001 and incorporated herein by reference).

                       

                       

                      78



                      10.4*

                       

                      Corporate Office Properties Trust Supplemental Nonqualified Deferred Compensation Plan (filed with the Registrant's Registration Statement on Form S-8 (Commission File No. 333-87384) and incorporated herein by reference).

                       

                       

                      10.5*

                       

                      Employment Agreement, dated December 16, 1999, between Corporate Office Management, Inc., COPT and Clay W. Hamlin, III (filed on March 16, 2000 with the Company's Annual Report on Form 10-K for the year ended December 31, 1999 and incorporated herein by reference).

                       

                       

                      10.6.1*

                       

                      Employment Agreement, dated July 13, 2005, between Corporate Office Properties, L.P. Corporate Office Properties Trust and Randall M. Griffin (filed with the Company's Current Report on Form 8-K on July 19, 2005 and incorporated herein by reference).

                       

                       

                      10.6.2*

                       

                      Amendment to Employment Agreement, dated May 30, 2006, between Corporate Office Properties, L.P., Corporate Office Properties Trust, and Randall M. Griffin (filed with the Company's Current Report on Form 8-K dated June 1, 2006 and incorporated herein by reference).

                       

                       

                      10.7.1*

                       

                      Employment Agreement, dated September 12, 2002, between the Operating Partnership, COPT and Roger A. Waesche, Jr. (filed on March 27, 2003 with the Company's Annual Report on Form 10-K for the year ended December 31, 2002 and incorporated herein by reference).

                       

                       

                      10.7.2*

                       

                      Amendment to Employment Agreement, dated March 4, 2005, between the Operating Partnership, COPT and Roger A. Waesche, Jr. (filed on March 16, 2005 with the Company's Annual Report on Form 10-K for the year ended December 31, 2004 and incorporated herein by reference).

                       

                       

                      10.7.3*

                       

                      Second Amendment to Employment Agreement, dated May 30, 2006, between Corporate Office Properties, L.P., Corporate Office Properties Trust, and Roger A. Waesche, Jr. (filed with the Company's Current Report on Form 8-K dated June 1, 2006 and incorporated herein by reference).

                       

                       

                      10.7.4*

                       

                      Third Amendment to Employment Agreement, dated July 31, 2006, between Corporate Office Properties, L.P., Corporate Office Properties Trust, and Roger A. Waesche, Jr. (filed with the Company's Current Report on Form 8-K dated August 1, 2006 and incorporated herein by reference).

                       

                       

                      10.7.5*

                       

                      Fourth Amendment to Employment Agreement, dated March 2, 2007, between Corporate Office Properties, L.P., Corporate Office Properties Trust, and Roger A. Waesche, Jr. (filed herewith).

                       

                       

                      10.8.1*

                       

                      Employment Agreement, dated May 15, 2003, between Corporate Development Services, LLC, Corporate Office Properties Trust and Dwight Taylor (filed on August 12, 2003 with the Registrant's Quarterly Report on Form 10-Q for the quarter ended June 30, 2003 and incorporated herein by reference).

                       

                       

                      10.8.2*

                       

                      Amendment to Employment Agreement, dated March 4, 2005, between Corporate Development Services, LLC, Corporate Office Properties Trust and Dwight Taylor (filed on March 16, 2005 with the Company's Annual Report on Form 10-K for the year ended December 31, 2004 and incorporated herein by reference).

                       

                       

                      79



                      10.8.3*

                       

                      Second Amendment to Employment Agreement, dated March 2, 2007, between Corporate Development Services, LLC, Corporate Office Properties Trust and Dwight S. Taylor (filed herewith).

                       

                       

                      10.9*

                       

                      Employment Agreement, dated November 18, 2005, between Corporate Office Properties, L.P. Corporate Office Properties Trust and Karen M. Singer (filed with the Company's Current Report on Form 8-K on December 1, 2005 and incorporated herein by reference).

                       

                       

                      10.10*

                       

                      Employment Agreement, dated July 31, 2006, between Corporate Office Properties, L.P., Corporate Office Properties Trust and Stephen E. Riffee (filed with the Company's Current Report on Form 8-K dated August 1, 2006 and incorporated herein by reference).

                       

                       

                      10.11

                       

                      Promissory Note, dated October 22, 1998, between Teachers Insurance and Annuity Association of America and the Operating Partnership (filed on November 13, 1998 with the Company's Quarterly Report on Form 10-Q for the quarter ended September 30, 1998 and incorporated herein by reference).

                       

                       

                      10.12

                       

                      Indemnity Deed of Trust, Assignment of Leases and Rents and Security Agreement, dated October 22, 1998, by affiliates of the Operating Partnership for the benefit of Teachers Insurance and Annuity Association of America (filed on November 13, 1998 with the Company's Quarterly Report on Form 10-Q for the quarter ended September 30, 1998 and incorporated herein by reference).

                       

                       

                      10.13

                       

                      Promissory Note, dated September 30, 1999, between Teachers Insurance and Annuity Association of America and the Operating Partnership (filed on November 8, 1999 with the Company's Quarterly Report on Form 10-Q for the quarter ended September 30, 1999 and incorporated herein by reference).

                       

                       

                      10.14

                       

                      Indemnity Deed of Trust, Assignment of Leases and Rents and Security Agreement, dated September 30, 1999, by affiliates of the Operating Partnership for the benefit of Teachers Insurance and Annuity Association of America (filed on November 8, 1999 with the Company's Quarterly Report on Form 10-Q for the quarter ended September 30, 1999 and incorporated herein by reference).

                       

                       

                      10.15

                       

                      Lease Agreement between Blue Bell Investment Company, L.P. and Unisys Corporation dated March 12, 1997 with respect to lot A (filed with the Registrant's Registration Statement on Form S-4 (Commission File No. 333-45649) and incorporated herein by reference).

                       

                       

                      10.16

                       

                      Lease Agreement between Blue Bell Investment Company, L.P. and Unisys Corporation, dated March 12, 1997, with respect to lot B (filed with the Registrant's Registration Statement on Form S-4 (Commission File No. 333-45649) and incorporated herein by reference).

                       

                       

                      10.17

                       

                      Lease Agreement between Blue Bell Investment Company, L.P. and Unisys Corporation, dated March 12, 1997, with respect to lot C (filed with the Registrant's Registration Statement on Form S-4 (Commission File No. 333-45649) and incorporated herein by reference).

                       

                       

                      10.18

                       

                      Option Agreement, dated March 1998, between the Operating Partnership and Blue Bell Land, L.P. (filed on March 16, 2000 with the Company's Annual Report on Form 10-K for the year ended December 31, 1999 and incorporated herein by reference).

                       

                       

                      80



                      10.19.1

                       

                      Amended and Restated Credit Agreement, dated June 24, 2005, among Corporate Office Properties, L.P.; Corporate Office Properties Trust; Wachovia Capital Markets, LLC; KeyBank National Association; Wachovia Bank, National Association; KeyBanc Capital Markets; Manufacturers and Traders Trust Company; Wells Fargo Bank, National Association; and Bank of America, N.A. (filed with the Company's Current Report on Form 8-K on June 30, 2005 and incorporated herein by reference).

                       

                       

                      10.19.2

                       

                      Second Amended and Restated Credit Agreement, dated October 1, 2007, among Corporate Office Properties, L.P.; Corporate Office Properties Trust; KeyBanc Capital Markets; Wachovia Capital Markets, LLC; KeyBank National Association; Wachovia Bank, National Association; Bank of America, N.A.; Manufacturers and Traders Trust Company; and Citizens Bank of Pennsylvania (filed herewith).

                       

                       

                      10.20

                       

                      Retirement and Consulting Agreement, dated April 12, 2005, between Corporate Office Properties, L.P. and Clay W. Hamlin, III (filed with the Company's Form 8-K on April 15, 2005 and incorporated herein by reference).

                       

                       

                      10.21

                       

                      Corporate Office Properties Trust Supplemental Nonqualified Deferred Compensation Plan (filed with the Company's Registration Statement on Form S-8 (Commission File No. 333-87384) and incorporated herein by reference).

                       

                       

                      10.22

                       

                      Common Stock Delivery Agreement, dated as of September 18, 2006, between Corporate Office Properties, L.P. and Corporate Office Properties Trust (filed with the Company's Current Report on Form 8-K dated September 22, 2006 and incorporated herein by reference).

                       

                       

                      10.23

                       

                      Purchase Agreement and Agreement and Plan of Merger, dated December 21, 2006, by and among the Corporate Office Properties Trust; Corporate Office Properties, L.P.; W&M Business Trust; and Nottingham Village, Inc. (filed on March 1, 2007 with the Company's Annual Report on Form 10-K for the year ended December 31, 2006 and incorporated herein by reference).

                       

                       

                      10.24

                       

                      Purchase and Sale Agreement of Ownership Interests, dated December 21, 2006, by and between Corporate Office Properties, L.P. and Nottingham Properties, Inc. (filed on March 1, 2007 with the Company's Annual Report on Form 10-K for the year ended December 31, 2006 and incorporated herein by reference).

                       

                       

                      10.25

                       

                      Description of Compensation of Non-Employee Trustees (filed herewith).

                       

                       

                      10.26

                       

                      Description of annual cash incentive awards to executives (filed herewith).

                       

                       

                      12.1

                       

                      Statement regarding Computation of Earnings to Combined Fixed Charges and Preferred Share Dividends (filed herewith).

                       

                       

                      21.1

                       

                      Subsidiaries of Registrant (filed herewith).

                       

                       

                      23.1

                       

                      Consent of Independent Registered Public Accounting Firm (filed herewith).

                       

                       

                      31.1

                       

                      Certification of the Chief Executive Officer of Corporate Office Properties Trust required by Rule 13a-14(a) under the Securities Exchange Act of 1934, as amended (filed herewith).

                       

                       

                      81



                      31.2

                       

                      Certification of the Chief Financial Officer of Corporate Office Properties Trust required by Rule 13a-14(a) under the Securities Exchange Act of 1934, as amended (filed herewith).

                       

                       

                      32.1

                       

                      Certification of the Chief Executive Officer of Corporate Office Properties Trust required by Rule 13a-14(b) under the Securities Exchange Act of 1934, as amended. (This exhibit shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liability of that section. Further, this exhibit shall not be deemed to be incorporated by reference into any filing under the Securities Exchange Act of 1933, as amended, or the Securities Exchange Act of 1934, as amended.) (Furnished herewith.)

                       

                       

                      32.2

                       

                      Certification of the Chief Financial Officer of Corporate Office Properties Trust required by Rule 13a-14(b) under the Securities Exchange Act of 1934, as amended. (This exhibit shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liability of that section. Further, this exhibit shall not be deemed to be incorporated by reference into any filing under the Securities Exchange Act of 1933, as amended, or the Securities Exchange Act of 1934, as amended.) (Furnished herewith.)

                       

                       

                      *
                      —Indicates a compensatory plan or arrangement required to be filed as an exhibit to this Form 10-K.

                              (c) Not applicable.

                      82



                      SIGNATURES

                              Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

                        CORPORATE OFFICE PROPERTIES TRUST

                      Date: February 29, 2008

                       

                      By:

                      /s/  
                      RANDALL M. GRIFFIN      
                      Randall M. Griffin
                      President and Chief Executive Officer

                      Date: February 29, 2008

                       

                      By:

                      /s/  
                      STEPHEN E. RIFFEE      
                      Stephen E. Riffee
                      Executive Vice President and Chief Financial Officer

                              Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the Registrant and in the capacities and on the dates indicated:

                      Signatures
                       Title
                       Date

                       

                       

                       

                       

                       
                      /s/  JAY H. SHIDLER      
                      (Jay H. Shidler)
                       Chairman of the Board and Trustee February 29, 2008

                      /s/  
                      CLAY W. HAMLIN, III      
                      (Clay W. Hamlin, III)

                       

                      Vice Chairman of the Board and Trustee

                       

                      February 29, 2008

                      /s/  
                      RANDALL M. GRIFFIN      
                      (Randall M. Griffin)

                       

                      President, Chief Executive Officer and Trustee

                       

                      February 29, 2008

                      /s/  
                      STEPHEN E. RIFFEE      
                      (Stephen E. Riffee)

                       

                      Executive Vice President and Chief Financial Officer (Principal Financial Officer)

                       

                      February 29, 2008

                      /s/  
                      COLLEEN M. CREWS      
                      (Colleen M. Crews)

                       

                      Vice President and Controller (Principal Accounting Officer)

                       

                      February 29, 2008

                      83



                      /s/  
                      THOMAS F. BRADY      
                      (Thomas F. Brady)

                       

                      Trustee

                       

                      February 29, 2008

                      /s/  
                      ROBERT L. DENTON      
                      (Robert L. Denton)

                       

                      Trustee

                       

                      February 29, 2008

                      /s/  
                      DOUGLAS M. FIRSTENBERG      
                      (Douglas M. Firstenberg)

                       

                      Trustee

                       

                      February 29, 2008

                      /s/  
                      STEVEN D. KESLER      
                      (Steven D. Kesler)

                       

                      Trustee

                       

                      February 29, 2008

                      /s/  
                      KENNETH S. SWEET, JR.      
                      (Kenneth S. Sweet, Jr.)

                       

                      Trustee

                       

                      February 29, 2008

                      /s/  
                      KENNETH D. WETHE      
                      (Kenneth D. Wethe)

                       

                      Trustee

                       

                      February 29, 2008

                      84



                      CORPORATE OFFICE PROPERTIES TRUST AND SUBSIDIARIES

                      INDEX TO FINANCIAL STATEMENTS

                      CONSOLIDATED FINANCIAL STATEMENTS  
                       
                      Management's Report of Internal Control Over Financial Reporting

                       

                      F-2
                       Report of Independent Registered Public Accounting Firm F-3
                       Consolidated Balance Sheets as of December 31, 2007 and 2006 F-4
                       Consolidated Statements of Operations for the Years Ended December 31, 2007, 2006 and 2005 F-5
                       Consolidated Statements of Shareholders' Equity for the Years Ended December 31, 2007, 2006 and 2005 F-6
                       Consolidated Statements of Cash Flows for the Years Ended December 31, 2007, 2006 and 2005 F-7
                       Notes to Consolidated Financial Statements F-8

                      FINANCIAL STATEMENT SCHEDULE

                       

                       

                      Schedule III—Real Estate and Accumulated Depreciation as of December 31, 2007

                       

                      F-57

                      F-1



                      Management's Report On Internal Control Over Financial Reporting

                              Management is responsible for establishing and maintaining adequate internal control over financial reporting, and for performing an assessment of the effectiveness of internal control over financial reporting as of December 31, 2007. Internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. Our internal control over financial reporting includes those policies and procedures that (i) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of our assets; (ii) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that our receipts and expenditures are being made only in accordance with authorizations of our management and trustees; and (iii) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use or disposition of our assets that could have a material effect on the financial statements. Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

                              Management performed an assessment of the effectiveness of our internal control over financial reporting as of December 31, 2007 based upon criteria in Internal Control—Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission ("COSO"). Based on our assessment, management determined that our internal control over financial reporting was effective as of December 31, 2007 based on the criteria in Internal Control-Integrated Framework issued by the COSO.

                              The effectiveness of the Company's internal control over financial reporting as of December 31, 2007 has been audited by PricewaterhouseCoopers LLP, an independent registered public accounting firm, as stated in their report which appears herein.

                      F-2



                      Report of Independent Registered Public Accounting Firm

                      To the Board of Trustees and Shareholders of Corporate Office Properties Trust:

                              In our opinion, the consolidated financial statements listed in the accompanying index 15(a)(1) present fairly, in all material respects, the financial position of Corporate Office Properties Trust and its subsidiaries at December 31, 2007 and December 31, 2006, and the results of their operations and their cash flows for each of the three years in the period ended December 31, 2007, in conformity with accounting principles generally accepted in the United States of America. In addition, in our opinion, the financial statement schedule listed in the accompanying index 15(a)(2) presents fairly, in all material respects, the information set forth therein when read in conjunction with the related consolidated financial statements. Also in our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2007, based on criteria established in Internal Control—Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO). The Company's management is responsible for these financial statements and financial statement schedule, for maintaining effective internal control over financial reporting and for its assessment of the effectiveness of internal control over financial reporting, included in the accompanying "Management Report's On Internal Control Over Financial Reporting." Our responsibility is to express opinions on these financial statements, on the financial statement schedule, and on the Company's internal control over financial reporting based on our integrated audits. We conducted our audits in accordance with the standards of the Public Company Accounting Oversight Board (United States). Those standards require that we plan and perform the audits to obtain reasonable assurance about whether the financial statements are free of material misstatement and whether effective internal control over financial reporting was maintained in all material respects. Our audits of the financial statements included examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, assessing the accounting principles used and significant estimates made by management, and evaluating the overall financial statement presentation. Our audit of internal control over financial reporting included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, and testing and evaluating the design and operating effectiveness of internal control based on the assessed risk. Our audits also included performing such other procedures as we considered necessary in the circumstances. We believe that our audits provide a reasonable basis for our opinions.

                              A company's internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company's internal control over financial reporting includes those policies and procedures that (i) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (ii) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (iii) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company's assets that could have a material effect on the financial statements.

                              Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

                      /s/ PricewaterhouseCoopers LLP

                      Baltimore, Maryland
                      February 29, 2008

                      F-3



                      Corporate Office Properties Trust and Subsidiaries

                      Consolidated Balance Sheets

                      (Dollars in thousands)

                       
                       December 31,
                       
                       
                       2007
                       2006
                       
                      Assets       
                      Investment in real estate:       
                       Operating properties, net $2,192,472 $1,812,883 
                       Property held for sale, net  14,988   
                       Projects under construction or development  396,012  298,427 
                        
                       
                       
                       Total commercial real estate properties, net  2,603,472  2,111,310 
                      Cash and cash equivalents  24,638  7,923 
                      Restricted cash  15,121  52,856 
                      Accounts receivable, net  24,831  26,367 
                      Deferred rent receivable  53,631  41,643 
                      Intangible assets on real estate acquisitions, net  108,661  87,325 
                      Deferred charges, net  49,051  43,710 
                      Prepaid and other assets  52,448  48,467 
                        
                       
                       
                      Total assets $2,931,853 $2,419,601 
                        
                       
                       
                      Liabilities and shareholders' equity       
                      Liabilities:       
                       Mortgage and other loans payable $1,625,842 $1,298,537 
                       3.5% Exchangeable Senior Notes  200,000  200,000 
                       Accounts payable and accrued expenses  75,363  68,190 
                       Rents received in advance and security deposits  30,978  20,237 
                       Dividends and distributions payable  22,441  19,164 
                       Deferred revenue associated with acquired operating leases  11,530  11,120 
                       Distributions in excess of investment in unconsolidated real       
                        estate joint venture  4,246  3,614 
                       Other liabilities  8,716  8,249 
                        
                       
                       
                      Total liabilities  1,979,116  1,629,111 
                        
                       
                       
                      Minority interests:       
                       Common units in the Operating Partnership  114,127  104,934 
                       Preferred units in the Operating Partnership  8,800  8,800 
                       Other consolidated real estate joint ventures  7,168  2,453 
                        
                       
                       
                      Total minority interests  130,095  116,187 
                        
                       
                       
                      Commitments and contingencies (Note 19)       
                      Shareholders' equity:       
                       Preferred Shares of beneficial interest ($0.01 par value); shares authorized of 15,000,000, issued and outstanding of 8,121,667 at December 31, 2007 and 7,590,000 at December 31, 2006 (Note 11)  81  76 
                       Common Shares of beneficial interest ($0.01 par value);
                      75,000,000 shares authorized, shares issued and outstanding of 47,366,475 at December 31, 2007 and 42,897,639 at December 31, 2006
                        474  429 
                       Additional paid-in capital  950,615  758,032 
                       Cumulative distributions in excess of net income  (126,156) (83,541)
                       Accumulated other comprehensive loss  (2,372) (693)
                        
                       
                       
                      Total shareholders' equity  822,642  674,303 
                        
                       
                       
                      Total liabilities and shareholders' equity $2,931,853 $2,419,601 
                        
                       
                       

                      See accompanying notes to consolidated financial statements.

                      F-4



                      Corporate Office Properties Trust and Subsidiaries

                      Consolidated Statements of Operations

                      (Dollars in thousands, except per share data)

                       
                       For the Years Ended December 31,
                       
                       
                       2007
                       2006
                       2005
                       
                      Revenues          
                       Rental revenue $315,588 $253,913 $208,144 
                       Tenant recoveries and other real estate operations revenue  53,361  39,665  28,665 
                       Construction contract revenues  37,074  52,182  74,357 
                       Other service operations revenues  4,151  7,902  4,877 
                        
                       
                       
                       
                        Total revenues  410,174  353,662  316,043 
                        
                       
                       
                       
                      Expenses          
                       Property operating expenses  123,282  92,907  70,337 
                       Depreciation and other amortization associated with real estate operations  106,331  78,054  60,427 
                       Construction contract expenses  35,723  49,961  72,534 
                       Other service operations expenses  4,070  7,384  4,753 
                       General and administrative expenses  20,523  16,936  13,533 
                        
                       
                       
                       
                        Total operating expenses  289,929  245,242  221,584 
                        
                       
                       
                       
                      Operating income  120,245  108,420  94,459 
                      Interest expense  (82,032) (70,260) (53,906)
                      Amortization of deferred financing costs  (3,676) (2,847) (2,229)
                      Gain on sale of non-real estate investment  1,033     
                        
                       
                       
                       
                      Income from continuing operations before equity in loss of unconsolidated entities, income taxes and minority interests  35,570  35,313  38,324 
                      Equity in loss of unconsolidated entities  (224) (92) (88)
                      Income tax expense  (569) (887) (668)
                        
                       
                       
                       
                      Income from continuing operations before minority interests  34,777  34,334  37,568 
                      Minority interests in income from continuing operations          
                       Common units in the Operating Partnership  (2,860) (3,302) (4,326)
                       Preferred units in the Operating Partnership  (660) (660) (660)
                       Other consolidated entities  122  136  85 
                        
                       
                       
                       
                      Income from continuing operations  31,379  30,508  32,667 
                      Income from discontinued operations, net of minority interests and taxes  1,845  17,987  6,096 
                        
                       
                       
                       
                      Income before gain on sales of real estate  33,224  48,495  38,763 
                      Gain on sales of real estate, net of minority interests and taxes  1,560  732  268 
                        
                       
                       
                       
                      Net income  34,784  49,227  39,031 
                      Preferred share dividends  (16,068) (15,404) (14,615)
                      Issuance costs associated with redeemed preferred shares    (3,896)  
                        
                       
                       
                       
                      Net income available to common shareholders $18,716 $29,927 $24,416 
                        
                       
                       
                       
                      Basic earnings per common share          
                       Income from continuing operations $0.36 $0.29 $0.49 
                       Discontinued operations  0.04  0.43  0.16 
                        
                       
                       
                       
                       Net income available to common shareholders $0.40 $0.72 $0.65 
                        
                       
                       
                       
                      Diluted earnings per common share          
                       Income from continuing operations $0.35 $0.28 $0.47 
                       Discontinued operations  0.04  0.41  0.16 
                        
                       
                       
                       
                       Net income available to common shareholders $0.39 $0.69 $0.63 
                        
                       
                       
                       
                      Dividends declared per common share $1.30 $1.18 $1.07 
                        
                       
                       
                       

                      See accompanying notes to consolidated financial statements.

                      F-5



                      Corporate Office Properties Trust and Subsidiaries

                      Consolidated Statements of Shareholders' Equity

                      (Dollars in thousands)

                       
                       Preferred
                      Shares

                       Common
                      Shares

                       Additional
                      Paid-in
                      Capital

                       Cumulative
                      Distributions in
                      Excess of Net
                      Income

                       Value of
                      Unearned
                      Restricted
                      Common Share
                      Grants

                       Accumulated
                      Other
                      Comprehensive
                      Loss

                       Total
                       
                      Balance at December 31, 2004 (36,842,108 common shares outstanding) $67 $368 $578,228 $(51,358)$(5,381)$ $521,924 
                      Conversion of common units to common shares (253,575 shares)    3  9,117        9,120 
                      Common shares issued to the public (2,300,000 shares)    23  75,118        75,141 
                      Decrease in fair value of derivatives            (482) (482)
                      Restricted common share grants issued (130,975 shares)    1  3,480    (3,481)    
                      Restricted common share cancellations (10,422 shares)      (205)   205     
                      Value of earned restricted share grants      536    1,544    2,080 
                      Exercise of share options (411,080 shares)    4  4,394        4,398 
                      Expense associated with share options      93        93 
                      Adjustments to minority interests resulting from changes in ownership of Operating Partnership by COPT      (12,888)       (12,888)
                      Decrease in tax benefit from share-based compensation      (534)       (534)
                      Net income        39,031      39,031 
                      Dividends        (55,370)     (55,370)
                        
                       
                       
                       
                       
                       
                       
                       
                      Balance at December 31, 2005 (39,927,316 common shares outstanding)  67  399  657,339  (67,697) (7,113) (482) 582,513 
                      Conversion of common units to common shares (245,793 shares)    3  11,075        11,078 
                      Common shares issued to the public (2,000,000 shares)    20  82,413        82,433 
                      Series J Preferred Shares issued to the public (3,390,000 shares)  34    81,823        81,857 
                      Series E Preferred Shares redemption  (11)   (28,739)       (28,750)
                      Series F Preferred Shares redemption  (14)   (35,611)       (35,625)
                      Decrease in fair value of derivatives            (211) (211)
                      Reversal of unearned restricted common share grants upon adoption of SFAS 123(R)    1  (5,169)   7,113    1,945 
                      Exercise of share options (581,932 shares)    6  6,761        6,767 
                      Expense associated with share-based compensation      3,833        3,833 
                      Adjustments to minority interests resulting from changes in ownership of Operating Partnership by COPT      (16,255)       (16,255)
                      Increase in tax benefit from share-based compensation      562        562 
                      Net income        49,227      49,227 
                      Dividends        (65,071)     (65,071)
                        
                       
                       
                       
                       
                       
                       
                       
                      Balance at December 31, 2006 (42,897,639 common shares outstanding)  76  429  758,032  (83,541)   (693) 674,303 
                      Conversion of common units to common shares (554,221 shares)    6  25,402        25,408 
                      Common shares issued in connection with acquisition of properties, net of transaction costs (3,161,000 shares)    32  156,629        156,661 
                      Series K Preferred Shares issued in connection with acquisition of properties, net of transaction costs (531,667 shares)  5    26,562        26,567 
                      Exercise of share options (620,858 shares)    6  7,470        7,476 
                      Expense associated with share-based compensation    1  6,642        6,643 
                      Restricted common share cancellations (6,685 shares)      (351)       (351)
                      Adjustments to minority interests resulting from changes in ownership of Operating Partnership by COPT      (29,761)       (29,761)
                      Decrease in fair value of derivatives            (1,679) (1,679)
                      Costs for equity issuance      (10)       (10)
                      Net income        34,784      34,784 
                      Dividends        (77,399)     (77,399)
                        
                       
                       
                       
                       
                       
                       
                       
                      Balance at December 31, 2007 (47,366,475 common shares outstanding) $81 $474 $950,615 $(126,156)$ $(2,372)$822,642 
                        
                       
                       
                       
                       
                       
                       
                       

                      See accompanying notes to consolidated financial statements.

                      F-6



                      Corporate Office Properties Trust and Subsidiaries

                      Consolidated Statements of Cash Flows

                      (Dollars in thousands)

                       
                       For the Years Ended December 31,
                       
                       
                       2007
                       2006
                       2005
                       
                      Cash flows from operating activities          
                       Net income $34,784 $49,227 $39,031 
                       Adjustments to reconcile net income to net cash provided by operating activities:          
                        Minority interests  4,220  7,800  6,464 
                        Depreciation and other amortization  107,625  80,074  63,555 
                        Amortization of deferred financing costs  3,676  2,981  2,240 
                        Amortization of deferred market rental revenue  (1,985) (1,904) (426)
                        Equity in loss of unconsolidated entities  224  92  88 
                        Gain on sales of real estate  (6,979) (17,920) (4,690)
                        Gain on sale of non-real estate investment  (1,033)    
                        Share-based compensation  6,643  3,833  2,173 
                        Excess income tax benefits from share-based compensation    (562)  
                       Changes in operating assets and liabilities:          
                        Increase in deferred rent receivable  (11,988) (10,004) (6,922)
                        Decrease (increase) in accounts receivable  1,544  (10,844) 1,165 
                        Increase in restricted cash and prepaid and other assets  (5,040) (7,098) (14,260)
                        (Decrease) increase in accounts payable, accrued expenses, and other liabilities  (3,250) 13,544  5,953 
                        Increase in rents received in advance and security deposits  10,030  4,181  1,993 
                        Other  (770) (249) (420)
                        
                       
                       
                       
                         Net cash provided by operating activities  137,701  113,151  95,944 
                        
                       
                       
                       
                      Cash flows from investing activities          
                       Purchases of and additions to commercial real estate properties  (352,427) (282,099) (499,926)
                       Proceeds from sales of properties  21,684  46,704  29,467 
                       Proceeds from sale of non-real estate investment  2,526     
                       Proceeds from sale of unconsolidated real estate joint venture    1,524   
                       Proceeds from contribution of assets to unconsolidated          
                        real estate joint venture      68,633 
                       Acquisition of partner interests in consolidated joint ventures  (1,262) (5,250) (1,208)
                       Investments in and advances from (to) unconsolidated entities    454  (130)
                       Distributions from unconsolidated entities  414  499  250 
                       Leasing costs paid  (12,182) (10,480) (9,272)
                       Decrease (increase) in restricted cash associated with          
                        investing activities  16,018  5,260  (5,620)
                       Purchases of furniture, fixtures and equipment  (1,663) (8,109) (2,434)
                       Other  (822) (2,337) (61)
                        
                       
                       
                       
                         Net cash used in investing activities  (327,714) (253,834) (420,301)
                        
                       
                       
                       
                      Cash flows from financing activities          
                       Proceeds from mortgage and other loans payable  867,842  673,176  889,399 
                       Proceeds from 3.5% Exchangeable Senior Notes    200,000   
                       Repayments of mortgage and other loans payable  (579,395) (762,590) (580,642)
                       Deferred financing costs paid  (4,171) (6,605) (4,307)
                       Distributions paid to partners in consolidated joint ventures  (250) (787)  
                       Net proceeds from issuance of common shares  7,446  89,202  79,539 
                       Net proceeds from issuance of preferred shares    81,857   
                       Redemption of preferred shares    (64,375)  
                       Dividends paid  (74,277) (62,845) (53,587)
                       Distributions paid  (11,188) (10,422) (9,677)
                       Excess income tax benefits from share-based compensation    562   
                       Other  721  649  595 
                        
                       
                       
                       
                         Net cash provided by financing activities  206,728  137,822  321,320 
                        
                       
                       
                       
                      Net increase (decrease) in cash and cash equivalents  16,715  (2,861) (3,037)
                      Cash and cash equivalents          
                       Beginning of period  7,923  10,784  13,821 
                        
                       
                       
                       
                       End of period $24,638 $7,923 $10,784 
                        
                       
                       
                       

                      See accompanying notes to consolidated financial statements.

                      F-7



                      Corporate Office Properties Trust and Subsidiaries

                      Notes to Consolidated Financial Statements

                      (Dollars in thousands, except per share data)

                      1. Organization

                              Corporate Office Properties Trust ("COPT") and subsidiaries (collectively, the "Company") is a fully-integrated and self-managed real estate investment trust ("REIT") that focuses on the acquisition, development, ownership, management and leasing of suburban office properties in select markets and submarkets. We also focus on servicing the multi-location requirements of strategic customers and strategic industries in which tenants have specialized product requirements. As of December 31, 2007, our investments in real estate included the following:

                        228 wholly owned operating properties totaling 17.8 million square feet;

                        19 wholly owned properties under construction or development that we estimate will total approximately 1.8 million square feet upon completion and one wholly owned office property totaling approximately 75,000 square feet that was under redevelopment;

                        wholly owned land parcels totaling 1,479 acres that we believe are potentially developable into approximately 12.4 million square feet; and

                        partial ownership interests in a number of other real estate projects in operations, under construction or redevelopment or held for future development.

                              We conduct almost all of our operations through our operating partnership, Corporate Office Properties, L.P. (the "Operating Partnership"), for which we are the managing general partner. The Operating Partnership owns real estate both directly and through subsidiary partnerships and limited liability companies ("LLCs"). A summary of our Operating Partnership's forms of ownership and the percentage of those ownership forms owned by COPT as of December 31, 2007 and 2006 follows:

                       
                       December 31,
                       
                       
                       2007
                       2006
                       
                      Common Units 85%83%
                      Series G Preferred Units 100%100%
                      Series H Preferred Units 100%100%
                      Series I Preferred Units 0%0%
                      Series J Preferred Units 100%100%
                      Series K Preferred Units(1) 100%N/A 

                          (1)
                          These preferred units were issued in 2007.

                      Three of our trustees controlled, either directly or through ownership by other entities or family members, an additional 13% of the Operating Partnership's common units.

                      F-8


                      Corporate Office Properties Trust and Subsidiaries

                      Notes to Consolidated Financial Statements (Continued)

                      (Dollars in thousands, except per share data)

                      1. Organization (Continued)

                              In addition to owning interests in real estate, the Operating Partnership also owns 100% of Corporate Office Management, Inc. ("COMI") and owns, either directly or through COMI, 100% of the consolidated subsidiaries that are set forth below (collectively defined as the "Service Companies"):

                      Entity Name

                       Type of Service Business
                      COPT Property Management Services, LLC ("CPM") Real Estate Management
                      COPT Development & Construction Services, LLC ("CDC") Construction and Development
                      Corporate Development Services, LLC ("CDS") Construction and Development
                      COPT Environmental Systems, LLC ("CES")(1) Heating and Air Conditioning

                          (1)
                          Prior to 2007, CES's name was Corporate Cooling and Controls, LLC.

                      Most of the services that CPM provides are for us. CDC, CDS and CES provide services to us and to third parties.

                      2. Summary of Significant Accounting Policies

                      Basis of Presentation

                              We generally use three different accounting methods to report our investments in entities: the consolidation method, the equity method and the cost method. These methods are described below.

                        Consolidation Method

                              We generally use the consolidation method when we own most of the outstanding voting interests in an entity and can control its operations. In accordance with Financial Accounting Standards Board ("FASB") Interpretation No. 46(R), "Consolidation of Variable Interest Entities" ("FIN 46(R)"), we also consolidate certain entities when control of such entities can be achieved through means other than voting rights ("variable interest entities" or "VIEs") if we are deemed to be the primary beneficiary. Generally, FIN 46(R) applies when either (1) the equity investors (if any) lack one or more of the essential characteristics of a controlling financial interest; (2) the equity investment at risk is insufficient to finance that entity's activities without additional subordinated financial support; or (3) the equity investors have voting rights that are not proportionate to their economic interests and the activities of the entity involve or are conducted on behalf of an investor with a disproportionately small voting interest.

                              Under the consolidation method of accounting, the accounts of the entity being consolidated are combined with our accounts. We eliminate balances and transactions between companies when we consolidate these accounts. For all of the periods presented, our Consolidated Financial Statements include the accounts of:

                        COPT;

                        the Operating Partnership and its subsidiary partnerships and LLCs (including consolidated joint ventures);

                        the Service Companies; and

                        Corporate Office Properties Holdings, Inc. (of which we own 100%).

                      F-9


                      Corporate Office Properties Trust and Subsidiaries

                      Notes to Consolidated Financial Statements (Continued)

                      (Dollars in thousands, except per share data)

                      2. Summary of Significant Accounting Policies (Continued)

                          Equity Method

                                We generally use the equity method of accounting when we own an interest in an entity and can exert significant influence over the entity's operations but cannot control the entity's operations. FIN 46(R) affects our determination of when to use the equity method of accounting since we would generally use the equity method for VIEs of which we are not the primary beneficiary. Under the equity method, we report:

                          our ownership interest in the entity's capital as an investment on our Consolidated Balance Sheets; and

                          our percentage share of the earnings or losses from the entity in our Consolidated Statements of Operations.

                          Cost Method

                                We use the cost method of accounting when we own an interest in an entity and cannot exert significant influence over the entity's operations. Under the cost method, we report:

                          the cost of our investment in the entity as an investment on our Consolidated Balance Sheets; and

                          distributions to us of the entity's earnings in our Consolidated Statements of Operations.

                        Use of Estimates in the Preparation of Financial Statements

                                We make estimates and assumptions when preparing financial statements under generally accepted accounting principles ("GAAP"). These estimates and assumptions affect various matters, including:

                          the reported amounts of assets and liabilities in our Consolidated Balance Sheets at the dates of the financial statements;

                          the disclosure of contingent assets and liabilities at the dates of the financial statements; and

                          the reported amounts of revenues and expenses in our Consolidated Statements of Operations during the reporting periods.

                        These estimates include such items as depreciation, allocation of real estate acquisition costs, allowances for doubtful accounts and expense recognized in connection with share-based compensation. Actual results could differ from those estimates. These estimates involve judgments with respect to, among other things, future economic factors that are difficult to predict and are often beyond management's control. As a result, actual amounts could differ from these estimates.

                        Acquisitions of Real Estate

                                We allocate the costs of real estate acquisitions to assets acquired and liabilities assumed based on the relative fair values at the date of acquisition pursuant to the provisions of Statement of Financial Accounting Standards No. 141, "Business Combinations." In estimating the fair value of the tangible and intangible assets acquired, we consider, among other things, information obtained about each property as a result of our due diligence, leasing activities and knowledge of the markets in which the

                        F-10


                        Corporate Office Properties Trust and Subsidiaries

                        Notes to Consolidated Financial Statements (Continued)

                        (Dollars in thousands, except per share data)

                        2. Summary of Significant Accounting Policies (Continued)


                        properties are located. We utilize various valuation methods, such as estimated cash flow projections utilizing discount and capitalization rate assumptions and available market information. We allocate the costs of real estate acquisitions to the following components:

                          Real estate based on a valuation of the acquired property performed with the assumption that the property is vacant upon acquisition (the "as if vacant value"). We then allocate the real estate value derived using this approach between land and building and improvements using our estimates and assumptions.

                          In-place operating leases to the extent that the present value of future rents under the contractual lease terms are above or below the present value of market rents at the time of acquisition (the "lease to market value"). For example, if we acquire a property and the leases in place for that property carry rents below the market rent for such leases at the time of acquisition, we classify as deferred revenue the amount equal to the difference between (1) the present value of the future rental revenue under the lease using market rent assumptions and (2) the present value of future rental revenue under the terms of the lease. Conversely, if the leases in place for that property carry rents above the market rent, we classify the difference as an intangible asset. Deferred revenue or deferred assets recorded in connection with the lease to market value of acquired properties are amortized into rental revenue over the terms of the leases.

                          Existing tenants in a property (the "lease-up value"). This amount represents the value associated with acquiring a built-in revenue stream on a leased building. It is computed as the difference between the present value of the property's: (1) revenues less operating expenses as if the property was vacant upon acquisition; and (2) revenues less operating expenses as if the property was acquired with leases in place at market rents.

                          Deemed cost avoidance of acquiring in-place operating leases ("deemed cost avoidance"). For example, when a new lease is entered into, the lessor typically incurs a number of origination costs in connection with the leases; such costs include tenant improvements and leasing costs. When a property is acquired with in-place leases, the origination costs for such leases were already incurred by the prior owner. Therefore, to recognize the value of these costs in recording a property acquisition, we assign value to the tenant improvements and leasing costs associated with the remaining term of in-place operating leases.

                          Tenant relationship value equal to the additional amount that we pay for a property in connection with the presence of a particular tenant in that property (the "tenant relationship value"). Our valuation of this component is affected by, among other things, our tenant lease renewal assumptions and evaluation of existing relationships with tenants.

                          Market concentration premium equal to the additional amount that we pay for a property over the fair value of assets in connection with our strategy of increasing our presence in regional submarkets (the "market concentration premium").

                        F-11


                        Corporate Office Properties Trust and Subsidiaries

                        Notes to Consolidated Financial Statements (Continued)

                        (Dollars in thousands, except per share data)

                        2. Summary of Significant Accounting Policies (Continued)

                          Commercial Real Estate Properties

                                  We report commercial real estate properties at our depreciated cost. The amounts reported for our commercial real estate properties include our costs of:

                            acquisitions;

                            development and construction;

                            building and land improvements; and

                            tenant improvements paid by us.

                                  We capitalize interest expense, real estate taxes, direct internal labor (including allocable overhead costs) and other costs associated with real estate undergoing construction and development activities to the cost of such activities. We continue to capitalize these costs while construction and development activities are underway until a property becomes "operational," which occurs upon the earlier of when leases commence on space or one year after the cessation of major construction activities. When leases commence on portions of a newly-constructed property's space in the period prior to one year from the cessation of major construction activities, we consider that property to be "partially operational." When a property is partially operational, we allocate the costs associated with the property between the portion that is operational and the portion under construction. We start depreciating newly-constructed properties as they become operational.

                                  We depreciate our assets evenly over their estimated useful lives as follows:

                           Buildings and building improvements 10-40 years
                           Land improvements 10-20 years
                           Tenant improvements on operating properties Related lease terms
                           Equipment and personal property 3-10 years

                                  When events or circumstances indicate that a property may be impaired, we perform an undiscounted cash flow analysis. We consider an asset to be impaired when its undiscounted expected future cash flows are less than its depreciated cost. When we determine that an asset is impaired, we utilize methods similar to those used by independent appraisers in estimating the fair value of the asset; this process requires us to make certain estimates and assumptions. We then recognize an impairment loss based on the excess of the carrying amount of the asset over its fair value. We have not recognized impairment losses on our real estate assets to date.

                                  When we determine that a real estate asset will be held for sale, we discontinue the recording of depreciation expense of the asset and estimate the sales price, net of selling costs; if we then determine that the estimated sales price, net of selling costs, is less than the net book value of the asset, we recognize an impairment loss equal to the difference and reduce the carrying amounts of assets.

                                  When we sell an operating property, or determine that an operating property is held for sale, and determine that we have no significant continuing involvement in such property, we classify the results of operations for such property as discontinued operations. Interest expense that is specifically identifiable to properties included in discontinued operations is used in the computation of interest expense attributable to discontinued operations. When properties classified as discontinued operations are

                          F-12


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          2. Summary of Significant Accounting Policies (Continued)


                          included in computations that determine the amount of our borrowing capacity under certain debt instruments (including our Revolving Credit Facility), we allocate a portion of such debt instruments' interest expense to discontinued operations; we compute this allocation based on the percentage that the related properties represent of all properties included in determining the amount of our borrowing capacity under such debt instruments.

                                  We expense property maintenance and repair costs when incurred.

                          Sales of Interests in Real Estate

                                  We recognize gains from sales of interests in real estate using the full accrual method, provided that various criteria relating to the terms of sale and any subsequent involvement by us with the real estate sold are met. We recognize gains relating to transactions that do not meet the requirements of the full accrual method of accounting when the full accrual method of accounting criteria are met.

                          Cash and Cash Equivalents

                                  Cash and cash equivalents include all cash and liquid investments that mature three months or less from when they are purchased. Cash equivalents are reported at cost, which approximates fair value. We maintain our cash in bank accounts in amounts that may exceed federally insured limits at times. We have not experienced any losses in these accounts in the past and believe that we are not exposed to significant credit risk because our accounts are deposited with major financial institutions.

                          Accounts Receivable

                                  Our accounts receivable are reported net of an allowance for bad debts of $448 at December 31, 2007 and $252 at December 31, 2006. We use judgment in estimating the uncollectability of our accounts receivable based primarily upon the payment history and credit status of the entities associated with the individual accounts.

                          Revenue Recognition

                                  We recognize rental revenue evenly over the terms of tenant leases. When our leases provide for contractual rent increases, which is most often the case, we average the non-cancelable rental revenues over the lease terms to evenly recognize such revenues; we refer to the adjustments resulting from this process as straight-line rental revenue adjustments. We consider rental revenue under a lease to be non-cancelable when a tenant: (1) may not terminate its lease obligation early; or (2) may terminate its lease obligation early in exchange for a fee or penalty that we consider material enough such that termination would not be probable. We report these straight-line rental revenue adjustments recognized in advance of payments received as deferred rent receivable on our Consolidated Balance Sheets. We report prepaid tenant rents as rents received in advance on our Consolidated Balance Sheets.

                                  When tenants terminate their lease obligations prior to the end of their agreed lease terms, they typically pay fees to cancel these obligations. We recognize such fees as revenue and write off against such revenue any (1) deferred rents receivable and (2) deferred revenue and intangible assets that are amortizable into rental revenue associated with the leases; the resulting net amount is the net revenue from the early termination of the leases. When a tenant's lease for space in a property is terminated

                          F-13


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          2. Summary of Significant Accounting Policies (Continued)


                          early but the tenant continues to lease such space under a new or modified lease in the property, the net revenue from the early termination of the lease is generally recognized evenly over the remaining life of the new or modified lease in place on that property.

                                  We recognize tenant recovery revenue in the same periods in which we incur the related expenses. Tenant recovery revenue includes payments from tenants as reimbursement for property taxes, utilities and other property operating expenses.

                                  We recognize fees for services provided by us once services are rendered, fees are determinable and collectibility is assured. We generally recognize revenue under construction contracts using the percentage of completion method when the contracts call for services to be provided over a period of time exceeding six months and the revenue and costs for such contracts can be estimated with reasonable accuracy; when these criteria do not apply to a contract, we recognize revenue on that contract once the services under the contract are complete. Under the percentage of completion method, we recognize a percentage of the total estimated revenue on a contract based on the cost of services provided on the contract as of a point in time relative to the total estimated costs on the contract.

                          Intangible Assets and Deferred Revenue on Real Estate Acquisitions

                                  We capitalize intangible assets and deferred revenue on real estate acquisitions as described in the section above entitled "Acquisitions of Real Estate." We amortize the intangible assets and deferred revenue as follows:

                           Lease to market value Related lease terms
                           Lease-up value Related lease terms or estimated period of time that tenant will lease space in property
                           Deemed cost avoidance Related lease terms
                           Tenant relationship value Estimated period of time that tenant will lease space in property
                           Market concentration premium 40 years

                                  We recognize the amortization of lease to market value assets and deferred revenues as adjustments to rental revenue reported in our Consolidated Statements of Operations; we refer to this amortization as amortization of deferred market rental revenue. We recognize the amortization of other intangible assets on real estate acquisitions as depreciation and amortization expense on our Consolidated Statements of Operations.

                          Deferred Charges

                                  We defer costs that we incur to obtain new tenant leases or extend existing tenant leases. We amortize these costs evenly over the lease terms. When tenant leases are terminated early, we expense any unamortized deferred leasing costs associated with those leases.

                                  We also defer costs for long-term financing arrangements and amortize these costs over the related loan terms on a straight-line basis, which approximates the amortization that would occur under the

                          F-14


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          2. Summary of Significant Accounting Policies (Continued)


                          effective interest method of amortization. We expense any unamortized loan costs when loans are retired early.

                                  When the costs of acquisitions exceed the fair value of tangible and identifiable intangible assets and liabilities, we record goodwill in connection with such acquisitions. We test goodwill annually for impairment and in interim periods if certain events occur indicating that the carrying value of goodwill may be impaired. We recognize an impairment loss when the discounted expected future cash flows associated with the related reporting unit are less than its unamortized cost.

                          Derivatives

                                  We are exposed to the effect of interest rate changes in the normal course of business. We use interest rate swap, interest rate cap and forward starting swap agreements in order to attempt to reduce the impact of such interest rate changes. Interest rate differentials that arise under interest rate swap and interest rate cap contracts are recognized in interest expense over the life of the respective contracts. Interest rate differentials that arise under forward starting swaps are recognized in interest expense over the life of the respective loans for which such swaps are obtained. We do not use such derivatives for trading or speculative purposes. We manage counter-party risk by only entering into contracts with major financial institutions based upon their credit ratings and other risk factors.

                                  We recognize all derivatives as assets or liabilities in the balance sheet at fair value with the offset to:

                            the accumulated other comprehensive loss component of shareholders' equity ("AOCL"), net of the share attributable to minority interests, for any derivatives designated as cash flow hedges to the extent such derivatives are deemed effective in hedging risks (risk in the case of our existing derivatives being defined as changes in interest rates);

                            interest expense on our Statements of Operations for any derivatives designated as cash flow hedges to the extent such derivatives are deemed ineffective in hedging risks; or

                            other revenue on our Statements of Operations for any derivatives designated as fair value hedges.

                                  We use standard market conventions and techniques such as discounted cash flow analysis, option pricing models, replacement cost and termination cost in computing the fair value of derivatives at each balance sheet date.

                          Minority Interests

                                  As discussed previously, we consolidate the accounts of our Operating Partnership and its subsidiaries into our financial statements. However, we do not own 100% of the Operating Partnership. We also do not own 100% of certain consolidated real estate joint ventures. The amounts reported for minority interests on our Consolidated Balance Sheets represent the portion of these consolidated entities' equity that we do not own. The amounts reported for minority interests on our Consolidated Statements of Operations represent the portion of these consolidated entities' net income not allocated to us.

                          F-15


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          2. Summary of Significant Accounting Policies (Continued)

                                  Common units of the Operating Partnership ("common units") are substantially similar economically to our common shares of beneficial interest ("common shares"). Common units not owned by us are also exchangeable into our common shares, subject to certain conditions.

                                  The Operating Partnership has 352,000 Series I Preferred Units issued to an unrelated party that have a liquidation preference of $25.00 per unit, plus any accrued and unpaid distributions of return thereon (as described below), and may be redeemed for cash by the Operating Partnership at our option any time after September 22, 2019. The owner of these units is entitled to a priority annual cumulative return equal to 7.5% of their liquidation preference through September 22, 2019; the annual cumulative preferred return increases for each subsequent five-year period, subject to certain maximum limits. These units are convertible into common units on the basis of 0.5 common units for each Series I Preferred Unit; the resulting common units would then be exchangeable for common shares in accordance with the terms of the Operating Partnership's agreement of limited partnership.

                          Earnings Per Share ("EPS")

                                  We present both basic and diluted EPS. We compute basic EPS by dividing net income available to common shareholders by the weighted average number of common shares outstanding during the year. Our computation of diluted EPS is similar except that:

                            the denominator is increased to include: (1) the weighted average number of potential additional common shares that would have been outstanding if securities that are convertible into our common shares were converted; and (2) the effect of dilutive potential common shares outstanding during the period attributable to share-based compensation using the treasury stock method; and

                            the numerator is adjusted to add back any convertible preferred dividends and any other changes in income or loss that would result from the assumed conversion into common shares that we added to the denominator.

                          Our computation of diluted EPS does not assume conversion of securities into our common shares if conversion of those securities would increase our diluted EPS in a given year. A summary of the

                          F-16


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          2. Summary of Significant Accounting Policies (Continued)


                          numerator and denominator for purposes of basic and diluted EPS calculations is set forth below (dollars and shares in thousands, except per share data):

                           
                           For the Years Ended December 31,
                           
                           
                           2007
                           2006
                           2005
                           
                          Numerator:          
                          Income from continuing operations $31,379 $30,508 $32,667 
                          Add: Gain on sales of real estate, net  1,560  732  268 
                          Less: Preferred share dividends  (16,068) (15,404) (14,615)
                          Less: Issuance costs associated with redeemed preferred shares    (3,896)  
                            
                           
                           
                           
                          Numerator for basic and diluted EPS from continuing operations  16,871  11,940  18,320 
                          Add: Income from discontinued operations, net  1,845  17,987  6,096 
                            
                           
                           
                           
                          Numerator for basic and diluted EPS on net income available to common shareholders $18,716 $29,927 $24,416 
                            
                           
                           
                           
                          Denominator (all weighted averages):          
                          Denominator for basic EPS (common shares)  46,527  41,463  37,371 
                          Dilutive effect of share-based compensation awards  1,103  1,799  1,626 
                            
                           
                           
                           
                          Denominator for diluted EPS  47,630  43,262  38,997 
                            
                           
                           
                           
                          Basic EPS:          
                           Income from continuing operations $0.36 $0.29 $0.49 
                           Income from discontinued operations  0.04  0.43  0.16 
                            
                           
                           
                           
                           Net income available to common shareholders $0.40 $0.72 $0.65 
                            
                           
                           
                           
                          Diluted EPS          
                           Income from continuing operations $0.35 $0.28 $0.47 
                           Income from discontinued operations $0.04 $0.41 $0.16 
                            
                           
                           
                           
                           Net income available to common shareholders $0.39 $0.69 $0.63 
                            
                           
                           
                           

                          Our diluted EPS computations do not include the effects of the following securities since the conversions of such securities would increase diluted EPS for the respective periods:

                           
                           Weighted Average
                          Shares Excluded
                          from Denominator
                          for the Years Ended December 31,

                           
                           2007
                           2006
                           2005
                          Conversion of weighted average common units 8,296 8,511 8,702
                          Conversion of weighted average convertible preferred units 176 176 176
                          Conversion of weighted average convertible preferred shares 425 N/A N/A
                          Share-based compensation awards   206

                          F-17


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          2. Summary of Significant Accounting Policies (Continued)

                                  As discussed in Note 9, on September 18, 2006, the Operating Partnership issued a $200,000 aggregate principal amount of 3.50% Exchangeable Senior Notes due 2026. The notes have an exchange settlement feature that provides that the notes may, under certain circumstances, be exchangeable for cash (up to the principal amount of the notes) and, with respect to any excess exchange value, may be exchangeable into (at our option) cash, our common shares or a combination of cash and our common shares at an exchange rate of 18.5249 shares per one thousand dollar principal amount of the notes (exchange rate is as of December 31, 2007 and is equivalent to an exchange price of $53.98 per common share). The Exchangeable Senior Notes did not affect our diluted EPS reported above since the weighted average closing price of our common shares during the period over which the notes were outstanding was less than $53.98.

                          Share-Based Compensation

                                  We have historically issued two forms of share-based compensation: options to purchase common shares ("options") and restricted common shares ("restricted shares"). Effective, January 1, 2006, we adopted Statement of Financial Accounting Standards No. 123(R), "Share-Based Payment" ("SFAS 123(R)"). The statement establishes standards for the accounting for transactions in which an entity exchanges its equity instruments for goods or services, focusing primarily on accounting for transactions in which an entity obtains employee services in share-based payment transactions. The statement requires us to measure the cost of employee services received in exchange for an award of equity instruments based generally on the fair value of the award on the grant date; such cost should then be recognized over the period during which the employee is required to provide service in exchange for the award (generally the vesting period). No compensation cost is recognized for equity instruments for which employees do not render the requisite service. SFAS 123(R) also requires that share-based compensation be computed based on awards that are ultimately expected to vest; as a result, future forfeitures of awards are to be estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. Effective upon our adoption of SFAS 123(R), we began capitalizing costs associated with share-based compensation attributable to employees engaged in construction and development activities. We used the modified prospective application approach to adoption provided for under SFAS 123(R); under this approach, we recognized compensation cost on or after January 1, 2006 for the portion of outstanding awards for which the requisite service was not yet rendered, based on the fair value of those awards on the date of grant.

                                  We elected to adopt the alternative transition method for calculating the tax effects of share-based compensation pursuant to SFAS 123(R). The alternative transition method includes a simplified method to establish the beginning balance of the additional paid-in capital pool related to the tax effects of employee share-based compensation, which is available to absorb tax deficiencies recognized subsequent to the adoption of SFAS 123(R).

                                  We compute the fair value of share options under SFAS 123(R) using the Black-Scholes option-pricing model. Under that model, the risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant. The expected option life is based on our historical experience of employee exercise behavior. Expected volatility is based on historical volatility of our common shares. Expected dividend yield is based on the average historical dividend yield on our common shares over a period of time ending on the grant date of the options.

                          F-18


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          2. Summary of Significant Accounting Policies (Continued)

                                  Prior to January 1, 2006, our general method for accounting for share-based compensation was as follows:

                            Options: These awards were accounted for using the intrinsic value method. Under this method, we recorded compensation expense only when the exercise price of a grant was less than the market price of our common shares on the option grant date; when this occurred, we recognized compensation expense equal to the difference between the exercise price and the grant-date market price over the service period to which the options related.

                            Restricted shares: We computed compensation expense for restricted share grants based on the value of such grants, as determined by the value of our common shares on the applicable measurement date (generally the date of grant). We recognized compensation expense for such grants over the service periods to which the grants related based on the vesting schedules for such grants.

                          Fair Value of Financial Instruments

                                  The carrying values of cash and cash equivalents, escrows, accounts receivables, accounts payable, accrued expenses and other assets and liabilities are reasonable estimates of their fair values because of the short maturities of these instruments. The carrying or contract values of notes receivable, which are included in prepaid and other assets on our Consolidated Balance Sheets, approximated their fair values at December 31, 2007 and 2006. You should refer to Notes 9 and 10 for fair value of debt and derivative information.

                          Reclassification

                                  We reclassified certain amounts from the prior periods in connection with discontinued operations to conform to the current period presentation of our Consolidated Financial Statements. These reclassifications did not affect previously reported consolidated net income or shareholders' equity.

                          Recent Accounting Pronouncement

                                  In June 2006, the FASB issued Interpretation No. 48, "Accounting for Uncertainty in Income Taxes—an interpretation of FASB Statement No. 109," ("FIN 48"). FIN 48 clarifies the accounting for uncertainty in income taxes recognized in an enterprise's financial statements in accordance with FASB Statement No. 109, "Accounting for Income Taxes." FIN 48 prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. FIN 48 also provides guidance on de-recognition, classification, interest and penalties, accounting in interim periods, disclosure and transition. FIN 48 is effective for fiscal years beginning after December 15, 2006. Our adoption of FIN 48 did not have a material effect on our financial position, results of operations or cash flows.

                          F-19


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          2. Summary of Significant Accounting Policies (Continued)

                                  In September 2006, the FASB issued Statement of Financial Accounting Standards No. 157, "Fair Value Measurements" ("SFAS 157"). SFAS 157 defines fair value, establishes a framework for measuring fair value in generally accepted accounting principles and expands disclosures about fair value measurements. The Statement does not require any new fair value measurements but does apply under other accounting pronouncements that require or permit fair value measurements. The changes to current practice resulting from the Statement relate to the definition of fair value, the methods used to measure fair value and the expanded disclosures about fair value measurements. SFAS 157 is effective for financial statements issued for fiscal years beginning after November 15, 2007 and interim periods within those fiscal years, with earlier application encouraged. We do not expect that the adoption of this Statement will have a material effect on our financial position, results of operations or cash flows.

                                  In February 2007, the FASB issued Statement of Financial Accounting Standards No. 159, "The Fair Value Option for Financial Assets and Financial Liabilities" ("SFAS 159"). SFAS 159 permits entities to choose to measure many financial assets and financial liabilities at fair value. Unrealized gains and losses on items for which the fair value option has been elected are reported in earnings. SFAS 159 is effective for fiscal years beginning after November 15, 2007. We are currently assessing the impact of SFAS 159 on our consolidated financial position and results of operations.

                                  In December 2007, the FASB issued Statement of Financial Accounting Standards No. 141(R), "Business Combinations" ("SFAS 141(R)"). SFAS 141(R) requires the acquiring entity in a business combination to recognize all (and only) the assets acquired and liabilities assumed in the transactions; establishes the acquisition-date fair value as the measurement objective for all assets acquired and liabilities assumed; and requires the acquirer to disclose to investors and other users all of the information they need to evaluate and understand the nature and financial effect of the business combination. SFAS 141(R) is effective for fiscal years beginning after December 15, 2008. While we are currently assessing the impact of SFAS 141(R) on our consolidated financial position and results of operations, we do believe that SFAS 141(R) will require us to expense transaction costs associated with property acquisitions, which is a significant change since our current practice is to capitalize such costs into the cost of acquisitions.

                                  In December 2007, the FASB issued Statement of Financial Accounting Standards No. 160, "Noncontrolling Interests in Consolidated Financial Statements" ("SFAS 160"). SFAS 160 requires all entities to report noncontrolling (minority) interests in subsidiaries in the same way—as equity in the consolidated financial statements. SFAS 160 is effective for fiscal years beginning after December 15, 2008. We are currently assessing the impact of SFAS 160 on our consolidated financial position and results of operations.

                          3. Concentration of Rental Revenue

                          Major Tenants

                                  The following table summarizes the percentage of our total rental revenue (which excludes tenant recoveries and other real estate operations revenue) earned from (1) individual tenants that accounted

                          F-20


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          3. Concentration of Rental Revenue (Continued)


                          for at least 5% of our rental revenue from continuing and discontinued operations and (2) the aggregate of the five tenants from which we recognized the most rental revenue in the respective years:

                           
                           For the Years Ended December 31,
                           
                           
                           2007
                           2006
                           2005
                           
                          United States Government 12%13%11%
                          Northrop Grumman Corporation(1) 9%N/A N/A 
                          Booz Allen Hamilton, Inc.  7%7%6%
                          Computer Sciences Corporation(1) N/A N/A 5%
                          Five largest tenants 31%32%30%

                              (1)
                              Includes affiliated organizations and agencies and predecessor companies.

                          Geographical Concentration

                                  We derived large concentrations of our total revenue from real estate operations (defined as the sum of rental revenue and tenant recoveries and other real estate operations revenue) from certain geographic regions. The table below sets forth certain of these concentrations:

                           
                           Percentage of Total Revenue
                          from Real Estate Operations
                          for the Years Ended December 31,

                           
                           
                           2007
                           2006
                           2005
                           
                          Mid-Atlantic region of United States 94%95%99%
                          Greater Washington, D.C.(1) 74%78%83%
                          Baltimore/Washington Corridor 47%48%49%

                              (1)
                              Comprised of our properties in the Baltimore/Washington Corridor (defined as the Maryland counties of Howard and Anne Arundel), Northern Virginia (defined as Fairfax County, Virginia), Suburban Maryland (defined as the Maryland counties of Montgomery, Prince George's and Frederick) and St. Mary's and King George Counties (located in Maryland and Virginia, respectively). This region is included in the Mid-Atlantic region of the United States.

                                  Substantially all of our construction contract and service operations revenues were derived from operations in the Greater Washington, D.C. region.

                          F-21


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          4. Commercial Real Estate Properties

                                  Operating properties consisted of the following:

                           
                           December 31,
                           
                           
                           2007
                           2006
                           
                          Land $413,779 $343,098 
                          Buildings and improvements  2,064,133  1,689,359 
                            
                           
                           
                             2,477,912  2,032,457 
                          Less: accumulated depreciation  (285,440) (219,574)
                            
                           
                           
                            $2,192,472 $1,812,883 
                            
                           
                           

                                  As of December 31, 2007, 429 Ridge Road, an office property located in Dayton, New Jersey that we were under contract to sell for $17,000, was classified as held for sale (Dayton, New Jersey is located in the Northern/Central New Jersey Region). We completed the sale of this property on January 31, 2008. The components associated with 429 Ridge Road as of December 31, 2007 included the following:

                           
                           December 31, 2007
                           
                          Land $2,932 
                          Buildings and improvements  15,003 
                            
                           
                             17,935 
                          Less: accumulated depreciation  (2,947)
                            
                           
                            $14,988 
                            
                           

                                  Projects we had under construction or development consisted of the following:

                           
                           December 31,
                           
                           2007
                           2006
                          Land $214,696 $153,436
                          Construction in progress  181,316  144,991
                            
                           
                            $396,012 $298,427
                            
                           

                          2007 Acquisitions

                                  On January 9 and 10, 2007, we completed a series of transactions that resulted in the acquisition of 56 operating properties totaling approximately 2.4 million square feet and land parcels totaling 187 acres. We refer to these transactions collectively as the Nottingham Acquisition. All of the acquired properties are located in Maryland, with 36 of the operating properties, totaling 1.6 million square feet, and land parcels totaling 175 acres, located in White Marsh, Maryland (located in the Suburban Baltimore, Maryland region ("Suburban Baltimore")) and the remaining properties and land parcels located in other regions in Northern Baltimore County and the Baltimore/Washington Corridor. We believe that the land parcels can support at least 2.0 million developable square feet. We completed the

                          F-22


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          4. Commercial Real Estate Properties (Continued)


                          Nottingham Acquisition for an aggregate cost of $366,852. The table below sets forth the allocation of the acquisition costs of the Nottingham Acquisition:

                          Land, operating properties $70,754 
                          Land, construction or development  37,309 
                          Building and improvements  210,264 
                          Intangible assets on real estate acquisitions  53,214 
                            
                           
                          Total assets  371,541 
                          Deferred revenue associated with acquired operating leases  (4,689)
                            
                           
                          Total acquisition cost $366,852 
                            
                           

                                  Intangible assets recorded in connection with the Nottingham Acquisition included the following:

                           
                            
                           Weighted
                          Average
                          Amortization
                          Period (in Years)

                          Tenant relationship value $25,778 8
                          Lease-up value  19,425 4
                          Lease cost portion of deemed cost avoidance  4,206 5
                          Lease to market value  3,805 4
                            
                            
                            $53,214 6
                            
                            

                                  Other acquisitions completed in 2007 included the following:

                            the remaining 50% undivided interest in a 132-acre parcel of land located in Colorado Springs, Colorado ("Colorado Springs") that we believe can support approximately 1.9 million developable square feet of office space for $13,586 on April 6, 2007; and

                            a 56-acre parcel of land located in Aberdeen, Maryland that we believe can support up to 800,000 developable square feet for $10,455 on September 14, 2007 (Aberdeen, Maryland is located in our Suburban Baltimore region). The property is located adjacent to Aberdeen Proving Ground, a United States Government installation.

                                  In addition, we acquired a 23-acre parcel of land located in Hanover, Maryland on July 2, 2007, with a fair value upon our acquisition of $9,829 (including improvements thereon contributed by us), through Arundel Preserve #5, LLC, a consolidated joint venture in which we own a 50% interest (Hanover, Marylandi s located in our Baltimore/Washington Corridor region). The joint venture is constructing an office property on the land parcel totaling approximately 152,000 square feet, and we believe the land parcel can support up to 303,000 additional developable square feet. We discuss joint ventures further in Note 5.

                          2007 Construction and Development Activities

                                  During 2007, we had five properties totaling 568,433 square feet (three located in the Baltimore/Washington Corridor and two in our Other region) become fully operational (68,196 of these square

                          F-23


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          4. Commercial Real Estate Properties (Continued)


                          feet were placed into service in 2006) and placed into service 48,377 square feet in a partially operational property located in the Baltimore/Washington Corridor.

                                  As of December 31, 2007, we had construction underway on four new buildings in the Baltimore/Washington Corridor (including the partially operational property discussed above and one property owned through Arundel Preserve #5, LLC), four in Colorado Springs and two in San Antonio, Texas ("San Antonio"). We also had development activities underway on four new buildings located in the Baltimore/Washington Corridor, two each in Colorado Springs and Suburban Baltimore and one each in Suburban Maryland and King George County, Virginia. In addition, we had redevelopment underway on one wholly owned existing building located in Colorado Springs and three properties owned by joint ventures (two are located in Northern Virginia and one in the Baltimore/Washington Corridor).

                          2007 Dispositions

                                  We sold the following operating properties in 2007:

                          Project Name

                           Location
                           Date of
                          Sale

                           Number
                          of
                          Buildings

                           Total
                          Rentable
                          Square Feet

                           Sale
                          Price

                           Gain
                          on Sale

                           
                          2 and 8 Centre Drive(1) Monroe, New Jersey 9/7/2007 2 32,331 $6,000 $1,931 
                          7321 Parkway Drive(2) Hanover, Maryland 9/7/2007 1 39,822  5,000  855 
                          10552 Philadelphia Road(3) White Marsh, Maryland 12/27/2007 1 56,000  6,800  1,127(4)
                                
                           
                           
                           
                           
                                4 128,153 $17,800 $3,913 
                                
                           
                           
                           
                           

                          (1)
                          Located in the Northern/Central New Jersey region.

                          (2)
                          Located in the Baltimore/Washington Corridor region.

                          (3)
                          Located in the Suburban Baltimore region.

                          (4)
                          Excluding income tax of $44 on this gain.

                                  We also sold three parcels of land in our Suburban Baltimore region totaling 16 acres developable into approximately 230,000 square feet for an aggregate of $8,687, resulting in a gain of $3,002 (excluding income tax of $1,069).

                          F-24


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          4. Commercial Real Estate Properties (Continued)

                          2006 Acquisitions

                                  We acquired the following office properties in 2006:

                          Project Name

                           Location
                           Date of
                          Acquisition

                           Number
                          of
                          Buildings

                           Total
                          Rentable
                          Square Feet

                           Initial
                          Cost

                          North Creek Colorado Springs, CO 5/18/2006 3 324,549 $41,508
                          1915 & 1925 Aerotech Drive Colorado Springs, CO 6/8/2006 2 75,892  8,378
                          7125 Columbia Gateway Drive Columbia, MD(1) 6/29/2006 1 611,379  74,168
                                
                           
                           
                                6 1,011,820 $124,054
                                
                           
                           

                          (1)
                          Located in the Baltimore/Washington Corridor.

                                  The table below sets forth the allocation of the acquisition costs of the properties described above:

                           
                           North Creek
                           1915 & 1925
                          Aerotech Drive

                           7125 Columbia
                          Gateway Drive

                           Total
                           
                          Land, operating properties $2,735 $1,113 $17,126 $20,974 
                          Building and improvements  34,161  6,161  46,964  87,286 
                          Intangible assets on real estate acquisitions  5,694  1,235  11,959  18,888 
                            
                           
                           
                           
                           
                          Total assets  42,590  8,509  76,049  127,148 
                          Deferred revenue associated with acquired operating leases  (1,082) (131) (1,881) (3,094)
                            
                           
                           
                           
                           
                          Total acquisition cost $41,508 $8,378 $74,168 $124,054 
                            
                           
                           
                           
                           

                                  We also acquired the following properties in 2006:

                          a property located in Colorado Springs containing a 74,749 square foot building that will be redeveloped and a four-acre parcel of land that we believe can support approximately 30,000 developable square feet for $2,602 on January 19, 2006;

                          a 31-acre parcel of land located in San Antonio that we believe can support approximately 375,000 developable square feet for $7,430 on January 20, 2006;

                          a six-acre parcel of land located in Hanover, Maryland that we believe can support approximately 60,000 developable square feet for $2,141 on February 28, 2006;

                          a 20-acre parcel of land located in Colorado Springs that we believe can support approximately 300,000 developable square feet for $1,060 on April 21, 2006;

                          a 13-acre parcel of land located in Colorado Springs that we believe can support approximately 150,000 developable square feet for $2,263 on May 19, 2006;

                          a 178-acre parcel of land located in Annapolis Junction, Maryland, located adjacent to the National Business Park, that we believe can support approximately 1.25 million developable square feet for

                          F-25


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          4. Commercial Real Estate Properties (Continued)

                            $26,833 on June 29, 2006 (Annapolis Junction, Maryland is located in the Baltimore/Washington Corridor);

                          a five-acre parcel of land located in Columbia, Maryland that we believe can support approximately 120,000 developable square feet for $3,361 on June 29, 2006;

                          a 28-acre parcel of land located in Chesterfield, Virginia on September 15, 2006 that was acquired under the terms of a lease for a 193,000 square foot building that we are constructing on the property (Chesterfield, Virginia, which is located in Greater Richmond, Virginia, is included in our "Other" business segment). The fair value of the land and closing costs associated with the title transfer totaled $1,303; and

                          approximately 500 acres of the 591-acre former Fort Ritchie United States Army base located in Cascade, Washington County, Maryland for a value of $5,576 (Washington County, Maryland is included in our "Other" business segment); we acquired the remaining 91 acres in 2007. The 591-acre parcel is anticipated to accommodate a total of 1.7 million square feet of office space and 673 residential units, including approximately 306,000 square feet of existing office space and 110 existing rentable residential units.

                                  In addition, we acquired the following properties through consolidated real estate joint ventures in 2006:

                            a land parcel located in the Baltimore/Washington Corridor, with a value upon our acquisition of $4,564, on February 10, 2006 through Commons Office 6-B, LLC, a 50% owned consolidated joint venture constructing an office property totaling approximately 44,000 square feet; and

                            a 153-acre parcel of land located near the Indian Head Naval Surface War Center in Charles County, Maryland, with a value upon our acquisition of $2,905, on October 23, 2006 through COPT-FD Indian Head, LLC, a 75% owned consolidated joint venture (Charles County, Maryland is included in our "Other" business segment).

                          We describe these joint ventures further in Note 5.

                          2006 Construction and Development Activities

                                  During 2006, we had seven properties totaling 866,000 square feet (four located in the Baltimore/Washington Corridor and one each in Northern Virginia, Colorado Springs and St. Mary's County, Maryland) become fully operational and had one property in the Baltimore/Washington Corridor become partially operational due to 68,196 square feet being placed into service.

                                  As of December 31, 2006, we had construction underway on four new buildings in the Baltimore/Washington Corridor (including the partially operational property discussed above and one property owned through a 50% joint venture) and one each in Suburban Baltimore, Colorado Springs, Chesterfield, Virginia and Southwest Virginia. We also had development activities underway on five new buildings located in the Baltimore/Washington Corridor (including one owned through a joint venture), two each in Suburban Maryland and Colorado Springs (one of which we own a 50% undivided interest) and one each in Suburban Baltimore and King George County, Virginia. In addition, we had redevelopment underway on two wholly owned existing buildings (one is located in the Baltimore/Washington Corridor and one in Colorado Springs) and two properties owned by a joint venture (one is located in Northern Virginia and one in the Baltimore/Washington Corridor).

                          F-26


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          4. Commercial Real Estate Properties (Continued)

                          2006 Dispositions

                                  We sold the following operating properties in 2006:

                          Project Name

                           Location
                           Date of
                          Sale

                           Number
                          of
                          Buildings

                           Total
                          Rentable
                          Square Feet

                           Sale Price
                           Gain on
                          Sale

                          Lakeview at the Greens Laurel, Maryland(1) 2/6/2006 2 141,783 $17,000 $2,087
                          68 Culver Road Dayton, New Jersey 3/8/2006 1 57,280  9,700  335
                          710 Route 46 Fairfield, New Jersey 7/26/2006 1 101,263  15,750  4,498
                          230 Schilling Circle Hunt Valley, Maryland(2) 8/9/2006 1 107,348  13,795  951
                          7 Centre Drive Monroe, New Jersey 8/30/2006 1 19,468  3,000  684
                          Brown's Wharf Baltimore, Maryland 9/28/2006 1 104,203  20,300  8,476
                                
                           
                           
                           
                                7 531,345 $79,545 $17,031
                                
                           
                           
                           

                          (1)
                          Located in the Suburban Maryland region.

                          (2)
                          Located in the Suburban Baltimore region.

                                  We also sold the following in 2006:

                            a newly constructed property in Columbia, Maryland for $2,530 on January 17, 2006. We recognized a gain of $111 on this sale; and

                            a two-acre parcel of land located in Linthicum Heights, Maryland for $900 on September 7, 2006 (Linthicum Heights, Maryland is located in the Baltimore/Washington Corridor). We recognized a gain of $165 on this sale.

                          5. Real Estate Joint Ventures

                                  During 2007, we had an investment in one unconsolidated real estate joint venture accounted for using the equity method of accounting. Information pertaining to this joint venture investment is set forth below.

                           
                           Balance at December 31,
                            
                            
                            
                            
                            
                           
                           Date
                          Acquired

                            
                           Nature of
                          Activity

                           Total
                          Assets at
                          12/31/2007

                           Maximum
                          Exposure
                          to Loss(1)

                           
                           2007
                           2006
                           Ownership
                          Harrisburg Corporate
                          Gateway Partners, L.P. 
                           $(4,246)(2) $(3,614)(2) 9/29/2005 20%Operates 16 buildings(3) $72,824 $

                          (1)
                          Derived from the sum of our investment balance and maximum additional unilateral capital contributions or loans required from us. Not reported above are additional amounts that we and our partner are required to fund when needed by this joint venture; these funding requirements are proportional to our respective ownership percentages. Also not reported above are additional unilateral contributions or loans from us, the amounts of which are uncertain, which we would be required to make if certain contingent events occur (see Note 19).

                          (2)
                          The carrying amount of our investment in this joint venture was lower than our share of the equity in the joint venture by $5,196 at December 31, 2007 and $5,072 at December 31, 2006 due to our deferral of gain on the contribution by us of real

                          F-27


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          5. Real Estate Joint Ventures (Continued)

                            estate into the joint venture upon its formation. A difference will continue to exist to the extent the nature of our continuing involvement in the joint venture remains the same.

                          (3)
                          This joint venture's property is located in Greater Harrisburg, Pennsylvania.

                                  A two-member management committee is responsible for making major decisions (as defined in the joint venture agreement) for Harrisburg Corporate Gateway Partners, L.P., and we control one of its management committee positions. Net cash flows of the joint venture are distributed to the partners in proportion to their respective ownership interests.

                                  The following table sets forth condensed balance sheets for Harrisburg Corporate Gateway Partners, L.P.:

                           
                           December 31,
                           
                           2007
                           2006
                          Commercial real estate property $71,205 $72,688
                          Other assets  1,619  3,207
                            
                           
                           Total assets $72,824 $75,895
                            
                           
                          Liabilities $67,991 $67,350
                          Owners' equity  4,833  8,545
                            
                           
                           Total liabilities and owners' equity $72,824 $75,895
                            
                           

                                  The following table sets forth combined condensed statements of operations for the two unconsolidated real estate joint ventures we owned from January 1, 2005 through December 31, 2007, which included Harrisburg Corporate Gateway Partners, L.P. and Route 46 Partners, a joint venture that was dissolved on July 26, 2006:

                           
                           For the Years Ended December 31,
                           
                           
                           2007
                           2006
                           2005
                           
                          Revenues $9,795 $11,521 $5,850 
                          Property operating expenses  (3,467) (4,067) (2,351)
                          Interest expense  (4,099) (4,224) (1,843)
                          Depreciation and amortization expense  (3,397) (4,464) (1,490)
                          Gain on sale    4,032   
                            
                           
                           
                           
                          Net (loss) income $(1,168)$2,798 $166 
                            
                           
                           
                           

                                  Prior to its dissolution, we had a 20% ownership interest in Route 46 Partners, a joint venture that operated one office property in Fairfield, New Jersey. Route 46 Partners sold the office property for $27,000 on July 26, 2006, after which the joint venture was dissolved, and we recognized a gain of $563 on the disposition of our joint venture interest. The table above includes net income from Route 46 Partners of $3,501 for 2006. Our joint venture partner in Route 46 Partners had preference in receiving distributions of cash flows for a defined return. We were not entitled to receive distributions for a defined return until our partner received its defined return. We did not recognize income from our

                          F-28


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          5. Real Estate Joint Ventures (Continued)


                          investment in Route 46 Partners in 2005 and 2006 until the dissolution of the entity since the income earned by the entity in those periods did not exceed our partner's defined return until that point in time. Upon dissolution of the entity, we recognized income from our investment of $60, excluding the $563 gain on disposition of the joint venture interest discussed above.

                                  We acquired the following interests in consolidated real estate joint ventures in 2006 and 2007:

                            a 50% interest in Commons Office 6-B, LLC in 2006. On February 10, 2006, this entity acquired a land parcel located in Hanover, Maryland, on which an office property totaling approximately 44,000 square feet was under construction. We acquired the remaining 50% interest in this entity for $1,262 on May 24, 2007;

                            a 75% interest in COPT—FD Indian Head, LLC in 2006. This entity acquired a 153-acre land parcel located near the Indian Head Naval Surface War Center in Charles County, Maryland on October 23, 2006. Net cash flows of the venture will be distributed to the partners in proportion to their respective ownership interests;

                            a 90% interest in Enterprise Campus Developer, LLC "Enterprise Campus"), the formation of which was completed on June 26, 2007. This entity was created to develop and construct one or more office buildings on land parcels located in College Park, Maryland as part of a joint venture called M Square Associates, LLC ("M Square") that was not formed until January 29, 2008, as discussed in Note 22 below (College Park, Maryland is located in the Suburban Maryland region). At December 31, 2007, development and construction activities were underway in anticipation of Enterprise Campus' impending membership into M Square. Net cash flows of the joint venture will be distributed to the partners as follows: (1) a $250 priority preferred return to us representing a return on a deposit we paid in lieu of a development bond on behalf of the joint venture; (2) the partners' preferred returns and capital investments in proportion to the partners' respective ownership interests; and (3) residual amounts according to a waterfall distribution schedule defined in the joint venture agreement under which our partner, who is acting as manager of day-to-day construction activities of the project, receives returns incrementally higher than its ownership percentage as net cash flows to the joint venture increase;

                            a 50% interest in Arundel Preserve #5, LLC, on July 2, 2007. The joint venture owns a land parcel located in Hanover, Maryland on which it is constructing an office property totaling approximately 152,000 square feet. We believe the land parcel can support up to 303,000 additional developable square feet. Our partner received a capital credit for its contribution of the land to the joint venture, and we are responsible for funding all development and construction costs for which financing is not obtained. Net cash flows will be distributed to the partners as follows: (1) preferred returns in proportion to the partners' respective capital accounts; (2) repayment of any building operating reserves funded by us; and (3) residual cash flows in proportion to the partners' respective ownership interests; and

                            a 92.5% interest in 13849 Park Center Road, LLC, a joint venture formed in 2007 to own property undergoing redevelopment that was previously owned by COPT Opportunity Invest, LLC. Net cash flows of the joint venture will be distributed to the partners in proportion to and to the extent of (1) their preferred returns (as defined in the joint venture agreement)

                          F-29


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          5. Real Estate Joint Ventures (Continued)

                              and (2) their capital accounts, and any residual amounts according to a waterfall distribution schedule defined in the joint venture agreement under which our partner, who is acting as manager of day-to-day construction activities of the project, receives returns incrementally higher than its ownership percentage as net cash flows to the joint venture increase.

                                  The table below sets forth information pertaining to our investments in consolidated joint ventures at December 31, 2007:

                           
                           Date
                          Acquired

                           Ownership
                          % at
                          12/31/2007

                           Nature of
                          Activity

                           Total
                          Assets at
                          12/31/2007

                           Collateralized
                          Assets at
                          12/31/2007

                          COPT Opportunity Invest I, LLC 12/20/2005 92.5%Redeveloping two properties(1) $45,876 $
                          Arundel Preserve #5, LLC 7/2/2007 50.0%Developing land parcel(2)  22,059  
                          Enterprise Campus Developer, LLC 6/26/2007 90.0%Developing land parcels(3)  14,208  
                          13849 Park Center Road, LLC 10/2/2007 92.5%Redeveloping one property(4)  6,696  
                          COPT-FD Indian Head, LLC 10/23/2006 75.0%Developing land parcel(5)  4,559  
                          MOR Forbes 2 LLC 12/24/2002 50.0%Operating one building(6)  4,403  
                                  
                           
                                  $97,801 $
                                  
                           

                          (1)
                          This joint venture owns one property in the Northern Virginia region and one in the Baltimore/Washington Corridor region.

                          (2)
                          This joint venture is developing a land parcel located in Hanover, Maryland.

                          (3)
                          This joint venture is developing land parcels located in College Park, Maryland.

                          (4)
                          This joint venture is redeveloping a property in the Northern Virginia region.

                          (5)
                          This joint venture's property is located in Charles County, Maryland (located in our "Other" business segment).

                          (6)
                          This joint venture's property is located in Lanham, Maryland (located in the Suburban Maryland region).

                                  Net cash flows of COPT Opportunity Invest I, LLC and MOR Forbes 2 LLC will be distributed to the partners in proportion to and to the extent of (1) their preferred returns (as defined in the joint venture agreements) and (2) their capital accounts, and any residual amounts according to a waterfall distribution schedule defined in the joint venture agreements under which our partners, who are acting as managers of day-to-day construction activities of the projects, receive returns incrementally higher than their ownership percentages as net cash flows to the joint venture increase.

                                  Our commitments and contingencies pertaining to our real estate joint ventures are disclosed in Note 19.

                          F-30


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          6. Intangible Assets on Real Estate Acquisitions

                                  Intangible assets on real estate acquisitions consisted of the following:

                           
                           December 31, 2007
                           December 31, 2006
                           
                           Gross Carrying
                          Amount

                           Accumulated
                          Amortization

                           Net Carrying
                          Amount

                           Gross Carrying
                          Amount

                           Accumulated
                          Amortization

                           Net Carrying
                          Amount

                          Lease-up value $125,338 $58,435 $66,903 $105,719 $38,279 $67,440
                          Tenant relationship value  35,188  7,892  27,296  9,371  1,178  8,193
                          Lease cost portion of deemed cost avoidance  17,133  8,697  8,436  12,880  5,819  7,061
                          Lease to market value  14,428  9,555  4,873  10,623  7,178  3,445
                          Market concentration premium  1,334  181  1,153  1,333  147  1,186
                            
                           
                           
                           
                           
                           
                            $193,421 $84,760 $108,661 $139,926 $52,601 $87,325
                            
                           
                           
                           
                           
                           

                                  Amortization of the intangible asset categories set forth above totaled $32,157 in 2007, $20,675 in 2006 and $12,525 in 2005. The approximate weighted average amortization periods of the categories set forth above follow: lease-up value: nine years; tenant relationship value: seven years; lease cost portion of deemed cost avoidance: five years; lease to market value: four years; and market concentration premium: 35 years. The approximate weighted average amortization period for all of the categories combined is nine years. Estimated amortization expense associated with the intangible asset categories set forth above is $21.1 million for 2008, $18.5 million for 2009, $14.3 million for 2010, $11.5 million for 2011 and $9.2 million for 2012.

                          7. Deferred Charges

                                  Deferred charges consisted of the following:

                           
                           December 31,
                           
                           
                           2007
                           2006
                           
                          Deferred leasing costs $63,052 $52,263 
                          Deferred financing costs  32,617  28,275 
                          Goodwill  1,853  1,853 
                          Deferred other  155  155 
                            
                           
                           
                             97,677  82,546 
                          Accumulated amortization  (48,626) (38,836)
                            
                           
                           
                          Deferred charges, net $49,051 $43,710 
                            
                           
                           

                          F-31


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          8. Prepaid and Other Assets

                                  Prepaid and other assets consisted of the following:

                           
                           December 31,
                           
                           2007
                           2006
                          Construction contract costs incurred in excess of billings $19,425 $18,324
                          Prepaid expenses  13,907  9,059
                          Furniture, fixtures and equipment  10,196  10,495
                          Other assets  8,920  10,589
                            
                           
                          Prepaid and other assets $52,448 $48,467
                            
                           

                          9. Debt

                                  Our debt consisted of the following:

                           
                            
                           Carrying Value at
                          December 31,

                            
                            
                           
                           Maximum
                          Principal Amount
                          Under Debt at
                          December 31, 2007

                            
                           Scheduled
                          Maturity
                          Dates at
                          December 31, 2007

                           
                           Stated Interest Rates
                          at December 31, 2007

                           
                           2007
                           2006
                          Mortgage and other loans payable:            
                           Revolving Credit Facility $600,000 $361,000 $185,000 LIBOR + 0.75% to 1.25%(1) September 30, 2011(2)
                              
                           
                              
                           Mortgage and Other Secured Loans            
                           Fixed rate mortgage loans(3) N/A  1,124,551  1,020,619 5.20%—8.63%(4) 2008 - 2034(5)
                           Variable rate construction loan facilities 111,500  104,089  56,079 LIBOR + 1.40% to 1.50%(6) 2008(7)
                           Other variable-rate secured loans N/A  34,500  34,500 LIBOR + 1.20% to 1.50%(8) 2008
                              
                           
                              
                            Total mortgage and other secured loans    1,263,140  1,111,198    
                              
                           
                              
                           Note payable            
                           Unsecured seller notes N/A  1,702  2,339 0%—5.95% 2008-2016
                              
                           
                              
                            Total mortgage and other loans payable    1,625,842  1,298,537    
                          3.5% Exchangeable Senior Notes N/A  200,000  200,000 3.50% September 2026(9)
                              
                           
                              
                            Total debt   $1,825,842 $1,498,537    
                              
                           
                              

                          (1)
                          The weighted average interest rate on the Revolving Credit Facility was 5.89% at December 31, 2007.

                          (2)
                          The Revolving Credit Facility may be extended for a one-year period at our option, subject to certain conditions.

                          (3)
                          Several of the fixed rate mortgages carry interest rates that were above or below market rates upon assumption and therefore are recorded at their fair value based on applicable effective interest rates. The carrying values of these loans reflect net premiums totaling $605 at December 31, 2007 and $210 at December 31, 2006.

                          (4)
                          The weighted average interest rate on these loans was 5.92% at December 31, 2007.

                          F-32


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          9. Debt (Continued)

                          (5)
                          A loan with a balance of $4,819 at December 31, 2007 that matures in 2034 may be repaid in March 2014, subject to certain conditions.

                          (6)
                          The weighted average interest rate on these loans was 6.48% at December 31, 2007.

                          (7)
                          At December 31, 2007, $84,589 in loans scheduled to mature in 2008 may be extended by us for a one-year period, subject to certain conditions; we expect to extend $40,589 of these loans.

                          (8)
                          The weighted average interest rate on these loans was 6.59% at December 31, 2007.

                          (9)
                          Refer to the paragraph below for descriptions of provisions for early redemption and repurchase of these notes.

                                  On October 1, 2007, we amended and restated the credit agreement on our Revolving Credit Facility with a group of lenders for which KeyBanc Capital Markets and Wachovia Capital Markets, LLC acted as co-lead arrangers, KeyBank National Association acted as administrative agent and Wachovia Bank, National Association acted as syndication agent. The amended and restated credit agreement increased the amount of the lenders' aggregate commitment under the facility from $500,000 to $600,000, which includes a $50,000 letter of credit subfacility and a $50,000 swingline facility (same-day draw requests), with a right for us to further increase the lenders' aggregate commitment during the term to a maximum of $800,000, subject to certain conditions. Amounts available under the facility are computed based on 65% of our unencumbered asset value, as defined in the agreement. The facility matures on September 30, 2011, and may be extended by one year at our option, subject to certain conditions. The variable interest rate on the facility is based on one of the following, to be selected by us: (1) the LIBOR rate for the interest period designated by us (customarily the 30-day rate) plus 0.75% to 1.25%, as determined by our leverage levels at different points in time; or (2) the greater of (a) the prime rate of the lender then acting as the administrative agent or (b) the Federal Funds Rate, as defined in the credit agreement, plus 0.50%. Interest is payable at the end of each interest period (as defined in the agreement), and principal outstanding under the facility is payable on the maturity date. The facility also carries a quarterly fee that is based on the unused amount of the facility multiplied by a per annum rate of 0.125% to 0.20%. As of December 31, 2007, the maximum amount of borrowing capacity under this line of credit totaled $600,000, of which $238,000 was available.

                                  On September 18, 2006, the Operating Partnership issued a $200,000 aggregate principal amount of 3.50% Exchangeable Senior Notes due 2026. Interest on the notes is payable on March 15 and September 15 of each year. The notes have an exchange settlement feature that provides that the notes may, under certain circumstances, be exchangeable for cash (up to the principal amount of the notes) and, with respect to any excess exchange value, may be exchangeable into (at our option) cash, our common shares or a combination of cash and our common shares at an exchange rate (subject to adjustment) of 18.5249 shares per one thousand dollar principal amount of the notes (exchange rate is as of December 31, 2007 and is equivalent to an exchange price of $53.98 per common share). On or after September 20, 2011, the Operating Partnership may redeem the notes in cash in whole or in part. The holders of the notes have the right to require us to repurchase the notes in cash in whole or in part on each of September 15, 2011, September 15, 2016 and September 15, 2021, or in the event of a "fundamental change," as defined under the terms of the notes, for a repurchase price equal to 100% of the principal amount of the notes plus accrued and unpaid interest. Prior to September 11, 2011, subject to certain exceptions, if (1) a "fundamental change" occurs as a result of certain forms of transactions or series of transactions and (2) a holder elects to exchange its notes in connection with

                          F-33


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          9. Debt (Continued)


                          such "fundamental change," we will increase the applicable exchange rate for the notes surrendered for exchange by a number of additional shares of our common shares as a "make whole premium." The notes are general unsecured senior obligations of the Operating Partnership and rank equally in right of payment with all other senior unsecured indebtedness of the Operating Partnership. The Operating Partnership's obligations under the notes are fully and unconditionally guaranteed by us.

                                  In the case of each of our mortgage loans, we have pledged certain of our real estate assets as collateral. As of December 31, 2007, a majority of our real estate properties were collateralized on loan obligations. Certain of our debt instruments require that we comply with a number of restrictive financial covenants, including adjusted consolidated net worth, minimum property interest coverage, minimum property hedged interest coverage, minimum consolidated interest coverage, maximum consolidated unhedged floating rate debt and maximum consolidated total indebtedness. As of December 31, 2007, we were in compliance with these financial covenants.

                                  Our debt matures on the following schedule:

                          2008 $297,120 
                          2009  62,643 
                          2010  74,033 
                          2011  470,814 
                          2012  42,200 
                          Thereafter  878,427 
                            
                           
                           Total $1,825,237(1)
                            
                           

                              (1)
                              Represents scheduled principal amortization and maturities only and therefore excludes net premiums of $605.

                                  We estimate that the fair value of our debt was $1,826,473 at December 31, 2007 and $1,510,698 at December 31, 2006.

                                  Weighted average borrowings under our Revolving Credit Facility totaled $298,901 in 2007 and $290,660 in 2006. The weighted average interest rate on this credit facility was 6.45% in 2007 and 6.42% in 2006.

                                  We capitalized interest costs of $19,274 in 2007, $14,559 in 2006 and $9,871 in 2005.

                          F-34


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          10. Derivatives

                                  The following table sets forth our derivative contracts and their respective fair values:

                           
                            
                            
                            
                            
                           Fair Value at December 31,
                           
                           
                           Notional
                          Amount

                           One-Month
                          LIBOR base

                           Effective
                          Date

                           Expiration
                          Date

                           
                          Nature of Derivative
                           2007
                           2006
                           
                          Interest rate swap $50,000 5.0360%3/28/2006 3/30/2009 $(765)$(42)
                          Interest rate swap  25,000 5.2320%5/1/2006 5/1/2009  (486) (133)
                          Interest rate swap  25,000 5.2320%5/1/2006 5/1/2009  (486) (133)
                          Interest rate swap  50,000 4.3300%10/23/2007 10/23/2009  (596) N/A 
                                     
                           
                           
                                     $(2,333)$(308)
                                     
                           
                           

                                  These amounts are included on our Consolidated Balance Sheets as other liabilities.

                                  We designated these derivatives as cash flow hedges. These contracts hedge the risk of changes in interest rates on certain of our one-month LIBOR-based variable rate borrowings until their respective maturities.

                                  The table below sets forth our accounting application of changes in derivative fair values:

                           
                           For the Years Ended December 31,
                           
                           2007
                           2006
                           2005
                          Decrease in fair value applied to         
                           AOCL(1) and minority interests $(2,025)$(308)$

                              (1)
                              AOCL is defined in Note 2.

                          11. Shareholders' Equity

                          Preferred Shares

                                  Preferred shares of beneficial interest ("preferred shares") consisted of the following:

                           
                           December 31,
                           
                           2007
                           2006
                          2,200,000 designated as Series G Cumulative Redeemable Preferred Shares of beneficial interest (2,200,000 shares issued with an aggregate liquidation preference of $55,000) $22 $22
                          2,000,000 designated as Series H Cumulative Redeemable Preferred Shares of beneficial interest (2,000,000 shares issued with an aggregate liquidation preference of $50,000)  20  20
                          3,390,000 designated as Series J Cumulative Redeemable Preferred Shares of beneficial interest (3,390,000 shares issued with an aggregate liquidation preference of $84,750)  34  34
                          531,667 designated as Series K Cumulative Redeemable Convertible Preferred Shares of beneficial interest (531,667 shares issued with an aggregate liquidation preference of $26,583)  5  
                            
                           
                          Total preferred shares $81 $76
                            
                           

                          F-35


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          11. Shareholders' Equity (Continued)

                                  Set forth below is a summary of additional information pertaining to our preferred shares of beneficial interest:

                          Series of Preferred
                          Share of Beneficial
                          Interest

                           # of Shares
                          Issued

                           Month of
                          Issuance

                           Annual
                          Dividend
                          Yield(1)

                           Annual
                          Dividend
                          Per Share

                           Earliest
                          Redemption
                          Date

                          Series E 1,150,000 April 2001 10.250%2.56250 NA(2)
                          Series F 1,425,000 September 2001 9.875%2.46875 NA(3)
                          Series G 2,200,000 August 2003 8.000%2.00000 8/11/2008
                          Series H 2,000,000 December 2003 7.500%1.87500 12/18/2008
                          Series J 3,390,000 July 2006 7.625%1.90625 7/20/2011
                          Series K 531,667 January 2007 5.600%2.80000 1/9/2017

                          (1)
                          Yield computed based on redemption price ($25 per share for Series E through Series J and $50 per share for Series K).

                          (2)
                          All outstanding Series E Preferred Shares were redeemed on July 15, 2006.

                          (3)
                          All outstanding Series F Preferred Shares were redeemed on October 15, 2006.

                                  Series E through Series J Preferred Shares of beneficial interest set forth in the table above are nonvoting and redeemable for cash at $25 per share at our option on or after the earliest redemption date. Series K Cumulative Redeemable Convertible Preferred Shares of beneficial interest ("Series K Preferred Shares") in the table above are nonvoting and redeemable for cash at $50 per share at our option on or after January 9, 2017. Holders of all preferred shares are entitled to cumulative dividends, payable quarterly (as and if declared by the Board of Trustees). In the case of each series of preferred shares, there is a series of preferred units in the Operating Partnership owned by us that carries substantially the same terms.

                                  On July 15, 2006, we redeemed all of the outstanding 10.25% Series E Cumulative Redeemable Preferred Shares of beneficial interest (the "Series E Preferred Shares") at a price of $25 per share, or $28,750. On October 15, 2006, we redeemed all of the outstanding Series F Cumulative Redeemable Preferred Shares of beneficial interest (the "Series F Preferred Shares") at a price of $25 per share, or $35,625. We recognized a $3,896 decrease to net income available to common shareholders pertaining to the original issuance costs incurred on the Series E and Series F Preferred Shares at the time of the redemption.

                                  On July 20, 2006, we completed the sale of 3.39 million Series J Cumulative Redeemable Preferred Shares (the "Series J Preferred Shares") at a price of $25 per share. We contributed the net proceeds after offering costs totaling $81,857 to our Operating Partnership in exchange for 3.39 million Series J Preferred Units. The Series J Preferred Units carry terms that are substantially the same as the Series J Preferred Shares.

                                  On January 9, 2007, we issued the Series K Preferred Shares in the Nottingham Acquisition at a value of, and liquidation preference equal to, $50 per share. The Series K Preferred Shares are nonvoting, redeemable for cash at $50 per share at our option on or after January 9, 2017, and are convertible, subject to certain conditions, into common shares on the basis of 0.8163 common shares

                          F-36


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          11. Shareholders' Equity (Continued)


                          for each preferred share, in accordance with the terms of the Articles Supplementary describing the Series K Preferred Shares. Holders of the Series K Preferred Shares are entitled to cumulative dividends, payable quarterly (as and if declared by our Board of Trustees). Dividends accrue from the date of issue at the annual rate of $2.80 per share, which is equal to 5.6% of the $50 per share liquidation preference.

                          Common Shares

                                  In April 2006, we sold 2.0 million common shares to an underwriter at a net price of $41.31 per share. We contributed the net proceeds after offering costs totaling $82,433 to our Operating Partnership in exchange for 2.0 million common units.

                                  In connection with the Nottingham Acquisition in January 2007, we issued 3.2 million common shares at a value of $49.57 per share.

                                  Over the three years ended December 31, 2007, common units in our Operating Partnership were converted into common shares on the basis of one common share for each common unit in the amount of 554,221 in 2007, 245,793 in 2006 and 253,575 in 2005.

                                  See Note 12 for disclosure regarding common share activity pertaining to our share-based compensation plans.

                          Accumulated Other Comprehensive Loss

                                  The table below sets forth activity in the accumulated other comprehensive loss component of shareholders' equity:

                           
                           For the Years Ended December 31,
                           
                           
                           2007
                           2006
                           2005
                           
                          Beginning balance $(693)$(482)$ 
                          Unrealized loss on derivatives, net of minority interests  (1,731) (262) (482)
                          Realized loss on derivatives, net of minority interests  52  51   
                            
                           
                           
                           
                          Ending balance $(2,372)$(693)$(482)
                            
                           
                           
                           

                                  The table below sets forth our comprehensive income:

                           
                           For the Years Ended December 31,
                           
                           
                           2007
                           2006
                           2005
                           
                          Net income $34,784 $49,227 $39,031 
                          Unrealized loss on derivatives, net of minority interests  (1,731) (262) (482)
                          Realized loss on derivatives, net of minority interests  52  51   
                            
                           
                           
                           
                          Total comprehensive income $33,105 $49,016 $38,549 
                            
                           
                           
                           

                          F-37


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          12. Share-based Compensation and Employee Benefit Plans

                          Share-based Compensation Plans

                                  In 1993, we adopted a plan for our Trustees under which we have 75,000 options reserved for issuance. These options expire ten years after the date of grant and are all exercisable. Shares for this plan are issued under a registration statement on Form S-8 that became effective upon filing with the Securities and Exchange Commission. As of December 31, 2007, there were no remaining awards available for future grant under this plan.

                                  In March 1998, we adopted a long-term incentive plan for our Trustees and employees. This plan provides for the award of options, restricted shares and dividend equivalents. We are authorized to issue awards under the plan amounting to no more than 13% of the total of (1) our common shares outstanding plus (2) the number of shares that would be outstanding upon redemption of all units of the Operating Partnership or other securities that are convertible into our common shares. Trustee options under this plan become exercisable beginning on the first anniversary of their grant. The vesting periods for employees' options under this plan range from immediately to five years, although they generally are three years. Options expire ten years after the date of grant. Restricted shares generally vest either over (1) a five-year period in specified percentages or (2) a three-year period in equal increments, beginning on the first anniversary of the grant date provided that the employees remain employed by us. Shares for this plan are issued under a registration statement on Form S-8 that became effective upon filing with the Securities and Exchange Commission. As of December 31, 2007, we had 975,504 awards available for future grant under this plan.

                          F-38


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          12. Share-based Compensation and Employee Benefit Plans (Continued)

                                  The following table summarizes option transactions under the plans described above:

                           
                           Shares
                           Range of
                          Exercise Price
                          per Share

                           Weighted
                          Average
                          Exercise
                          Price per
                          Share

                           Weighted
                          Average
                          Remaining
                          Contractual
                          Term
                          (in Years)

                           Aggregate
                          Intrinsic
                          Value

                          Outstanding at December 31, 2004 2,687,084 $5.38–$28.69 $11.43     
                          Granted—2005 521,588 $25.52–$36.08 $28.38     
                          Forfeited/Expired—2005 (87,665)$10.00–$34.89 $23.60     
                          Exercised—2005 (411,080)$5.38–$25.05 $10.70     
                            
                                    
                          Outstanding at December 31, 2005 2,709,927 $5.63–$36.08 $14.41     
                          Granted—2006 503,800 $36.24–$50.59 $42.84     
                          Forfeited/Expired—2006 (68,107)$13.60–$47.79 $33.43     
                          Exercised—2006 (589,101)$5.63–$34.76 $11.49     
                            
                                    
                          Outstanding at December 31, 2006 2,556,519 $7.38–$50.59 $20.18 6 $77,447
                          Granted—2007 297,691 $42.40–$57.00 $47.87     
                          Forfeited/Expired—2007 (99,177)$20.34–$53.16 $42.31     
                          Exercised—2007 (613,689)$5.25–$44.73 $12.18     
                            
                                    
                          Outstanding at December 31, 2007 2,141,344 $7.38–$57.00 $25.29 6 $22,639
                            
                                    
                          Exercisable at December 31, 2005 2,054,919  (1)$10.58     
                            
                                    
                          Exercisable at December 31, 2006 1,753,428  (2)$12.65     
                            
                                    
                          Exercisable at December 31, 2007 1,507,876  (3)$18.05 5 $22,248
                            
                                    
                          Options expected to vest 589,125 $25.52–$57.00 $42.54 9 $364
                            
                                    

                          (1)
                          486,250 of these options had an exercise price ranging from $5.63 to $7.99; 854,027 had an exercise price ranging from $8.00 to $10.99; 590,104 had an exercise price ranging from $11.00 to $16.99; and 124,538 had an exercise price ranging from $17.00 to $28.69.

                          (2)
                          234,082 of these options had an exercise price ranging from $7.38 to $7.99; 754,068 had an exercise price ranging from $8.00 to $10.99; 456,732 had an exercise price ranging from $11.00 to $16.99; 198,241 had an exercise price ranging from $17.00 to $25.99; and 110,305 had an exercise price range of $26.00 to $36.08.

                          (3)
                          232,982 of these options had an exercise price ranging from $7.38 to $7.99; 291,762 had an exercise price ranging from $8.00 to $10.99; 406,211 had an exercise price ranging from $11.00 to $16.99; 237,382 had an exercise price ranging from $17.00 to $25.99; 163,648 had an exercise price ranging from $26.00 to $34.99; 130,265 had an exercise price ranging from $35.00 to $43.99; and 45,626 had an exercise price ranging from $44.00 to $52.99.

                          The aggregate intrinsic value of options exercised was $23,627 in 2007, $19,748 in 2006 and $8,366 in 2005.

                          F-39


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          12. Share-based Compensation and Employee Benefit Plans (Continued)

                                  We received proceeds from the exercise of options of $7,476 in 2007, $6,767 in 2006 and $4,398 in 2005.

                                  We computed share-based compensation expense under the fair value method using the Black-Scholes option-pricing model; the weight average assumptions we used in that model are set forth below:

                           
                           For the Years Ended December 31,
                           
                           
                           2007
                           2006
                           2005
                           
                          Weighted average fair value of grants on grant date $9.58 $8.99 $2.82 
                          Risk-free interest rate(1)  4.64% 4.91% 3.97%
                          Expected life-years  6.15  6.82  6.00 
                          Expected volatility(2)  21.46% 23.69% 22.70%
                          Expected dividend yield(3)  3.24% 3.82% 6.90%

                              (1)
                              Ranged from 4.53% to 4.91% in 2007 and from 4.38% to 5.30% in 2006.

                              (2)
                              Ranged from 21.28% to 21.75% in 2007 and from 22.37% to 25.11% in 2006.

                              (3)
                              Ranged from 3.12% to 3.35% in 2007 and from 3.36% to 4.25% in 2006.

                                  A summary of the weighted average grant-date fair value per option granted is as follows:

                           
                           For the Years Ended December 31,
                           
                           2007
                           2006
                           2005
                          Weighted average grant-date fair value $9.58 $8.99 $2.82
                          Weighted average grant-date fair value—exercise price equals market price on grant-date $9.58 $8.99 $2.83
                          Weighted average grant-date fair value—exercise price exceeds market price on grant-date  N/A  N/A $2.51
                          Weighted average grant-date fair value—exercise price less than market price on grant-date  N/A  N/A  N/A

                                  The weighted average grant date fair value of option issuances increased significantly in 2006 over previous years due in large part to a large decrease in the weighted average dividend yield assumption in 2006. We derive our dividend yield assumption from the average historical dividend yield on our common shares over a period of time ending on the grant date of options. Prior to 2006, we used a longer historical timeframe for purposes of estimating our dividend yield assumption. In response to the trading price for our common shares having increased significantly through 2006, which had a decreasing effect on our dividend yield, we concluded that the use of a shorter historical timeframe for estimating the dividend yield assumption was appropriate.

                          F-40


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          12. Share-based Compensation and Employee Benefit Plans (Continued)

                                  The following table summarizes restricted share transactions under the plans described above for 2007 and 2006:

                           
                           Shares
                           Weighted
                          Average
                          Grant Date
                          Fair Value

                          Unvested at December 31, 2005 395,609 $19.88
                          Granted 163,420 $42.65
                          Forfeited (20,822)$23.67
                          Vested (124,517)$17.16
                            
                             
                          Unvested at December 31, 2006 413,690 $29.51
                          Granted 141,359 $49.50
                          Forfeited (1,917)$50.57
                          Vested (137,227)$22.54
                            
                             
                          Unvested at December 31, 2007 415,905 $38.50
                            
                             
                          Restricted shares expected to vest 395,110   
                            
                             

                                  The fair value of restricted shares that vested during the year ended December 31, 2007 was $6,938. The fair value of restricted shares that vested during the year ended December 31, 2006 was $5,319.

                                  We realized a windfall tax benefit of $562 in 2006 on options exercised and restricted shares vested by employees of our subsidiaries that are subject to income tax. We did not realize a windfall tax benefit in 2007 because COMI had a net operating loss carryforward for tax purposes; had COMI not had a net operating loss carryforward in 2007, we would have recognized a windfall tax benefit of $1,691 in 2007.

                          F-41


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          12. Share-based Compensation and Employee Benefit Plans (Continued)

                                  The table below sets forth information relating to expenses from share-based compensation included in our Consolidated Statements of Operations:

                           
                           For the Years Ended
                          December 31,

                           
                           
                           2007
                           2006
                           
                          Increase in general and administrative expenses $4,461 $2,659 
                          Increase in construction contract and other service operations expenses  1,749  964 
                            
                           
                           
                          Share-based compensation expense  6,210  3,623 
                          Income taxes  (150) (107)
                          Minority interests  (946) (617)
                            
                           
                           
                          Net share-based compensation expense $5,114 $2,899 
                            
                           
                           

                          Net share-based compensation expense per share

                           

                           

                           

                           

                           

                           

                           
                           Basic $0.11 $0.07 
                           Diluted $0.11 $0.07 

                                  We also capitalized share-based compensation costs of approximately $433 in 2007 and $212 in 2006.

                                  The amounts included in our Consolidated Statements of Operations for share-based compensation reflected an estimate of pre-vesting forfeitures of 7% for options and a range of 2% to 5% for restricted shares for the year ended December 31, 2007 and 5% for all share-based awards in the year ended December 31, 2006.

                                  As of December 31, 2007, there was $3,392 of unrecognized compensation cost related to nonvested options that is expected to be recognized over a weighted average period of approximately two years. As of December 31, 2007, there was $10,913 of unrecognized compensation cost related to unvested restricted shares that is expected to be recognized over a weighted average period of approximately three years.

                          Disclosure for Periods Prior to 2006, Including Pro Forma Financial Information Under SFAS 123

                                  Expenses from share-based compensation reflected in our Consolidated Statements of Operations for the year ended December 31, 2005 were as follows:

                           
                           For the Year Ended
                          December 31, 2005

                          Increase in general and administrative expenses $1,903
                          Increase in construction contract and other service operations expenses  230

                          F-42


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          12. Share-based Compensation and Employee Benefit Plans (Continued)

                                  The following table summarizes our operating results for the year ended December 31, 2005 as if we elected to account for our share-based compensation under the fair value provisions of SFAS 123 in those periods:

                           
                           For the Year Ended
                          December 31, 2005

                           
                          Net income, as reported $39,031 
                           Add: Share-based compensation expense, net of related tax effects and minority interests, included in the determination of net income  1,670 
                           Less: Share-based compensation expense determined under the fair value based method, net of related tax effects and minority interests  (1,671)
                            
                           
                          Net income, pro forma $39,030 
                            
                           
                          Basic EPS on net income available to common shareholders, as reported $0.65 
                          Basic EPS on net income available to common shareholders, pro forma $0.65 
                          Diluted EPS on net income available to common shareholders, as reported $0.63 
                          Diluted EPS on net income available to common shareholders, pro forma $0.63 

                                  In computing the amounts reflected above, we accounted for forfeitures as they occurred and we did not capitalize costs associated with share-based compensation.

                          401(k) Plan

                                  We have a 401(k) defined contribution plan covering substantially all of our employees that permits participants to defer up to a maximum of 15% of their compensation. We match a participant's contribution in an amount equal to 50% of the participant's elective deferral for the plan year up to a maximum of 6% of a participant's annual compensation. Employees' contributions are fully vested and our matching contributions vest in annual one-third increments. Once an employee has been with us for three years, all matching contributions are fully vested. We fund all contributions with cash. Our matching contributions under the plan totaled approximately $442 in 2007, $538 in 2006 and $396 in 2005. The 401(k) plan is fully funded at December 31, 2007.

                          Deferred Compensation Plan

                                  We have a non-qualified elective deferred compensation plan for certain members of our management team that permits participants to defer up to 100% of their compensation on a pre-tax basis and receive a tax-deferred return on such deferrals. We match the participant's contribution in an amount equal to 50% of the participant's elective deferral for the plan year up to a maximum of 6% of a participant's annual compensation after deducting contributions, if any, made under our 401(k) plan. Deferred compensation related to an employee contribution is charged to expense and is fully vested.

                          F-43


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          12. Share-based Compensation and Employee Benefit Plans (Continued)


                          Deferred compensation related to the Company's matching contribution is charged to expense and vests in annual one-third increments. Once an employee has been with us for three years, all matching contributions are fully vested. The balance of the plan, which was fully funded, totaled $6,014 at December 31, 2007 and $5,195 at December 31, 2006, and is included in the accompanying Consolidated Balance Sheets.

                          13. Related Party Transactions

                                  We earned fees from unconsolidated joint ventures totaling $458 in 2007, $619 in 2006 and $326 in 2005. These fees were for property management, construction and leasing services performed.

                          14. Operating Leases

                                  We lease our properties to tenants under operating leases with various expiration dates extending to the year 2025. Gross minimum future rentals on noncancelable leases in our consolidated properties at December 31, 2007 were as follows:

                          For the Years Ended December 31,
                            
                          2008 $312,664
                          2009  275,274
                          2010  222,978
                          2011  183,754
                          2012  146,720
                          Thereafter  542,382
                            
                           Total $1,683,772
                            

                                  We consider a lease to be noncancelable when a tenant (1) may not terminate its lease obligation early or (2) may terminate its lease obligation early in exchange for a fee or penalty that we consider material enough such that termination would be highly unlikely.

                          F-44


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          15. Supplemental Information to Statements of Cash Flows

                           
                           For the Years Ended December 31,
                           
                           
                           2007
                           2006
                           2005
                           
                          Interest paid, net of capitalized interest $84,278 $68,617 $57,100 
                            
                           
                           
                           
                          Income taxes paid $123 $54 $ 
                            
                           
                           
                           
                          Supplemental schedule of non-cash investing and financing activities:          
                          Debt assumed in connection with acquisitions $38,996 $39,011 $17,347 
                            
                           
                           
                           
                          Issuance of common shares in connection with acquisition of properties (before transaction costs) $156,691 $ $ 
                            
                           
                           
                           
                          Issuance of preferred shares in connection with acquisition of properties (before transaction costs) $26,583 $ $ 
                            
                           
                           
                           
                          Proceeds from sales of properties invested in restricted cash account $701 $33,730 $ 
                            
                           
                           
                           
                          Restricted cash used in connection with acquisitions of properties $20,827 $ $ 
                            
                           
                           
                           
                          Issuance of common units in the Operating Partnership in connection with acquisition of properties (before transaction costs) $12,125 $7,497 $2,647 
                            
                           
                           
                           
                          Issuance of common units in the Operating Partnership in connection with contribution of properties accounted for under the financing method of accounting $ $ $3,687 
                            
                           
                           
                           
                          Increase (decrease) in accrued capital improvements and leasing costs $8,638 $18,181 $(9,349)
                            
                           
                           
                           
                          Reclassification of operating assets to investment assets in connection with consolidation of real estate joint ventures $16,725 $ $ 
                            
                           
                           
                           
                          Consolidation of real estate joint venture:          
                           Real estate assets $3,864 $ $ 
                           Prepaid and other assets  1,021     
                           Minority interest  (4,885)    
                            
                           
                           
                           
                           Net adjustment $ $ $ 
                            
                           
                           
                           
                          Property acquired through lease arrangement included in rents received in advance and security deposits $711 $1,282 $ 
                            
                           
                           
                           
                          Amortization of discounts and premiums on mortgage loans to commercial real estate properties $307 $196 $273 
                            
                           
                           
                           
                          Decrease in fair value of derivatives applied to AOCL and minority interests $(2,025)$(308)$ 
                            
                           
                           
                           
                          Adjustments to minority interests resulting from changes in ownership of Operating Partnership by COPT $29,761 $16,255 $12,888 
                            
                           
                           
                           
                          Dividends/distribution payable $22,441 $19,164 $16,703 
                            
                           
                           
                           
                          Decrease in minority interests and increase in shareholders' equity in connection with the conversion of common units into common shares $25,408 $11,078 $9,120 
                            
                           
                           
                           
                          Issuance of restricted shares $ $ $3,276 
                            
                           
                           
                           

                          F-45


                          Corporate Office Properties Trust and Subsidiaries
                          Notes to Consolidated Financial Statements (Continued)
                          (Dollars in thousands, except per share data)

                          16. Information by Business Segment

                                  As of December 31, 2007, we had nine primary office property segments: Baltimore/Washington Corridor; Northern Virginia; Suburban Baltimore; Colorado Springs; Suburban Maryland; Greater Philadelphia; St. Mary's and King George Counties; San Antonio; and Northern/Central New Jersey. We also had an office property segment in Greater Harrisburg, Pennsylvania prior to the contribution of our properties in that region into a real estate joint venture in exchange for cash and a 20% interest in such joint venture on September 29, 2005.

                                  The table below reports segment financial information. Our segment entitled "Other" includes assets and operations not specifically associated with the other defined segments, including corporate assets and investments in unconsolidated entities. We measure the performance of our segments based on total revenues less property operating expenses, a measure we define as net operating income ("NOI"). We believe that NOI is an important supplemental measure of operating performance for a REIT's operating real estate because it provides a measure of the core operations that is unaffected by depreciation, amortization, financing and general and administrative expenses; this measure is particularly useful in our opinion in evaluating the performance of geographic segments, same-office property groupings and individual properties.

                           
                           Baltimore/
                          Washington
                          Corridor

                           Northern
                          Virginia

                           Suburban
                          Baltimore

                           Colorado
                          Springs

                           Suburban
                          Maryland

                           Greater
                          Philadelphia

                           St. Mary's &
                          King George
                          Counties

                           San
                          Antonio

                           Northern/
                          Central New
                          Jersey

                           Greater
                          Harrisburg

                           Other
                           Intersegment
                          Eliminations

                           Total
                          Year Ended December 31, 2007                                       
                          Revenues $173,509 $72,402 $54,570 $15,304 $16,675 $10,025 $12,665 $7,370 $4,846 $ $7,583 $(3,430)$371,519
                          Property operating expenses  56,818  25,892  22,013  5,901  6,665  126  3,054  1,577  2,047    4,709  (3,862) 124,940
                            
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                          NOI $116,691 $46,510 $32,557 $9,403 $10,010 $9,899 $9,611 $5,793 $2,799 $ $2,874 $432 $246,579
                            
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                          Additions to commercial real estate properties $159,702 $23,696 $280,234 $49,904 $2,927 $1,236 $1,040 $3,204 $688 $ $61,036 $(2,077)$581,590
                            
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                          Segment assets at December 31, 2007 $1,215,497 $482,570 $448,093 $181,639 $131,020 $96,051 $95,208 $59,296 $40,672 $ $181,194 $613 $2,931,853
                            
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                          Year Ended December 31, 2006                                       
                          Revenues $147,648 $63,515 $28,570 $9,776 $15,316 $10,025 $12,087 $7,441 $12,295 $(6)$1,668 $(2,543)$305,792
                          Property operating expenses  45,667  22,727  11,889  3,659  5,710  168  3,116  1,533  3,311  (49) 2,042  (3,740) 96,033
                            
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                          NOI $101,981 $40,788 $16,681 $6,117 $9,606 $9,857 $8,971 $5,908 $8,984 $43 $(374)$1,197 $209,759
                            
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                          Additions to commercial real estate properties $190,038 $21,638 $6,206 $66,628 $4,664 $1,202 $1,823 $8,814 $1,398 $5 $39,466 $(1,720)$340,162
                            
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                          Segment assets at December 31, 2006 $1,081,356 $473,540 $162,786 $135,118 $117,573 $97,795 $97,661 $52,661 $48,499 $ $155,043 $(2,431)$2,419,601
                            
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                          Year Ended December 31, 2005                                       
                          Revenues $123,819 $60,255 $11,099 $1,006 $12,555 $10,025 $12,852 $1,814 $13,779 $6,605 $169 $(1,619)$252,359
                          Property operating expenses  37,373  20,348  4,367  407  4,791  157  2,784  334  5,737  2,209  1,971  (4,238) 76,240
                            
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                          NOI $86,446 $39,907 $6,732 $599 $7,764 $9,868 $10,068 $1,480 $8,042 $4,396 $(1,802)$2,619 $176,119
                            
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                          Additions to commercial real estate properties $144,334 $57,972 $110,085 $57,901 $58,707 $872 $5,739 $42,658 $2,199 $449 $884 $(465)$481,335
                            
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                          Segment assets at December 31, 2005 $901,718 $463,179 $189,576 $63,767 $130,221 $99,357 $99,191 $42,884 $67,206 $ $73,423 $(763)$2,129,759
                            
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           

                          F-46


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          16. Information by Business Segment (Continued)

                                  The following table reconciles our segment revenues to total revenues as reported on our Consolidated Statements of Operations:

                           
                           For the Years Ended December 31,
                           
                           
                           2007
                           2006
                           2005
                           
                          Segment revenues $371,519 $305,792 $252,359 
                          Construction contract revenues  37,074  52,182  74,357 
                          Other service operations revenues  4,151  7,902  4,877 
                          Less: Revenues from discontinued operations (Note 18)  (2,570) (12,214) (15,550)
                            
                           
                           
                           
                          Total revenues $410,174 $353,662 $316,043 
                            
                           
                           
                           

                                  The following table reconciles our segment property operating expenses to property operating expenses as reported on our Consolidated Statements of Operations:

                           
                           For the Years Ended December 31,
                           
                           
                           2007
                           2006
                           2005
                           
                          Segment property operating expenses $124,940 $96,033 $76,240 
                          Less: Property expenses from discontinued real estate operations (Note 18)  (1,658) (3,126) (5,903)
                            
                           
                           
                           
                          Total property operating expenses $123,282 $92,907 $70,337 
                            
                           
                           
                           

                          F-47


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          16. Information by Business Segment (Continued)

                                  The following table reconciles our NOI for reportable segments to income from continuing operations as reported on our Consolidated Statements of Operations:

                           
                           For the Years Ended December 31,
                           
                           
                           2007
                           2006
                           2005
                           
                          NOI for reportable segments $246,579 $209,759 $176,119 
                          Construction contract revenues  37,074  52,182  74,357 
                          Other service operations revenues  4,151  7,902  4,877 
                          Equity in loss of unconsolidated entities  (224) (92) (88)
                          Income tax expense  (569) (887) (668)
                          Other adjustments:          
                           Depreciation and other amortization associated with real estate operations  (106,331) (78,054) (60,427)
                           Construction contract expenses  (35,723) (49,961) (72,534)
                           Other service operations expenses  (4,070) (7,384) (4,753)
                           General and administrative expenses  (20,523) (16,936) (13,533)
                           Interest expense on continuing operations  (82,032) (70,260) (53,906)
                           Gain on sale of non-real estate investment  1,033     
                           Amortization of deferred financing costs  (3,676) (2,847) (2,229)
                           Minority interests in continuing operations  (3,398) (3,826) (4,901)
                           NOI from discontinued operations  (912) (9,088) (9,647)
                            
                           
                           
                           
                          Income from continuing operations $31,379 $30,508 $32,667 
                            
                           
                           
                           

                                  The accounting policies of the segments are the same as those previously disclosed for Corporate Office Properties Trust and subsidiaries, where applicable. We did not allocate interest expense, amortization of deferred financing costs and depreciation and other amortization to segments since they are not included in the measure of segment profit reviewed by management. We also did not allocate construction contract revenues, other service operations revenues, construction contract expenses, other service operations expenses, equity in loss of unconsolidated entities, general and administrative expense, income taxes and minority interests because these items represent general corporate items not attributable to segments.

                          17. Income Taxes

                                  Corporate Office Properties Trust elected to be treated as a REIT under Sections 856 through 860 of the Internal Revenue Code. To qualify as a REIT, we must meet a number of organizational and operational requirements, including a requirement that we distribute at least 90% of our adjusted taxable income to our shareholders. As a REIT, we generally will not be subject to Federal income tax if we distribute at least 100% of our taxable income to our shareholders and satisfy certain other requirements (see discussion below). If we fail to qualify as a REIT in any tax year, we will be subject to Federal income tax on our taxable income at regular corporate rates and may not be able to qualify as a REIT for four subsequent tax years.

                          F-48


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          17. Income Taxes (Continued)

                                  The differences between taxable income reported on our income tax return (estimated 2007 and actual 2006 and 2005) and net income as reported on our Consolidated Statements of Operations are set forth below:

                           
                           For the Years Ended December 31,
                           
                           
                           2007
                           2006
                           2005
                           
                           
                           (Estimated)
                            
                            
                           
                          Net income $34,784 $49,227 $39,031 
                          Adjustments:          
                           Rental revenue recognition  (6,102) (8,186) (7,225)
                           Compensation expense recognition  (18,986) (17,079) (5,068)
                           Operating expense recognition  194  (118) (68)
                           Gain on sales of properties  6,451  (10,690) 7,174 
                           Losses from service operations  (844) (1,401) (1,780)
                           Income tax expense  569  887  699 
                           Depreciation and amortization  44,337  26,554  18,668 
                           Earnings from unconsolidated real estate joint ventures  342  709  307 
                           Minority interests, gross  (1,350) 1,862  (4,828)
                           Other  (166) (191) (737)
                            
                           
                           
                           
                          Taxable income $59,229 $41,574 $46,173 
                            
                           
                           
                           

                                  For Federal income tax purposes, dividends to shareholders may be characterized as ordinary income, capital gains or return of capital. The characterization of dividends declared on our common and preferred shares during each of the last three years was as follows:

                           
                           Common Shares
                           Preferred Shares
                           
                           
                           For the Years Ended December 31,
                           For the Years Ended December 31,
                           
                           
                           2007
                           2006
                           2005
                           2007
                           2006
                           2005
                           
                          Ordinary income 59.5%50.3%70.7%78.4%87.4%79.9%
                          Long term capital gain 16.4%7.2%17.8%21.6%12.6%20.1%
                          Return of capital 24.1%42.5%11.5%0.0%0.0%0.0%

                                  We distributed all of our REIT taxable income in 2007, 2006 and 2005 and, as a result, did not incur Federal income tax in those years on such income. However, we did incur income tax totaling $1,112 in 2007 on built-in gain on properties, which is included in the Consolidated Statements of Operations as follows: $1,068 in gain in sales of real estate, net of minority interests and income taxes; and $44 in discontinued operations net of minority interests and income taxes.

                          F-49


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          17. Income Taxes (Continued)

                                  COMI is subject to Federal and state income taxes. COMI had income before income taxes under GAAP of $1,476 in 2007, $2,288 in 2006 and $1,780 in 2005. COMI's provision for income tax consisted of the following:

                           
                           For the Years Ended December 31,
                           
                           2007
                           2006
                           2005
                          Deferred         
                           Federal $468 $641 $572
                           State  104  141  127
                            
                           
                           
                             572  782  699
                            
                           
                           
                          Current         
                           Federal    86  
                           State    19  
                            
                           
                           
                               105  
                            
                           
                           
                          Total $572 $887 $699
                            
                           
                           

                                  A reconciliation of COMI's Federal statutory rate to the effective tax rate for income tax reported on our Statements of Operations is set forth below:

                           
                           For the Years Ended December 31,
                           
                           
                           2007
                           2006
                           2005
                           
                          Income taxes at U.S. statutory rate 34.0%34.0%34.0%
                          State and local, net of U.S. Federal tax benefit 4.6%4.6%4.7%
                          Other 0.1%0.2%0.6%
                            
                           
                           
                           
                          Effective tax rate 38.7%38.8%39.3%
                            
                           
                           
                           

                                  Items contributing to temporary differences that lead to deferred taxes include net operating losses that are not deductible until future periods, depreciation and amortization, share-based compensation, certain accrued compensation and compensation paid in the form of contributions to a deferred nonqualified compensation plan. COMI had a net operating loss carryforward for income taxes of approximately $1,062 at December 31, 2007.

                                  We are subject to certain state and local income and franchise taxes. The expense associated with these state and local taxes is included in general and administrative expense on our Consolidated Statements of Operations. We did not separately state these amounts on our Consolidated Statements of Operations because they are insignificant.

                          F-50


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          18. Discontinued Operations

                                  Income from discontinued operations includes revenues and expenses associated with the following:

                            three properties located in the Northern/Central New Jersey region that were sold on September 8, 2005;

                            two Lakeview at the Greens properties that were sold on February 6, 2006;

                            68 Culver Road property that was sold on March 8, 2006;

                            710 Route 46 property that was sold on July 26, 2006;

                            230 Schilling Circle property that was sold on August 9, 2006;

                            7 Centre Drive property that was sold on August 30, 2006;

                            Brown's Wharf property that was sold on September 28, 2006;

                            2 and 8 Centre Drive properties that were sold on September 7, 2007;

                            7321 Parkway property that was sold on September 7, 2007;

                            10552 Philadelphia Road property that was sold on December 27, 2007; and

                            429 Ridge Road property that we were under contract to sell as of December 31, 2007 and was classified as held for sale.

                                  Certain reclassifications have been made in prior periods to reflect discontinued operations consistent with the current period presentation. The table below sets forth the components of income from discontinued operations:

                           
                           For the Years Ended December 31,
                           
                           
                           2007
                           2006
                           2005
                           
                          Revenue from real estate operations $2,570 $12,214 $15,550 
                            
                           
                           
                           
                          Expenses from real estate operations:          
                           Property operating expenses  1,658  3,126  5,903 
                           Depreciation and amortization  1,294  2,020  3,128 
                           Interest expense  1,250  2,160  3,238 
                           Other  5  135  12 
                            
                           
                           
                           
                            Expenses from real estate operations  4,207  7,441  12,281 
                            
                           
                           
                           
                          Income from discontinued operations before gain on sales of real estate and minority interests  (1,637) 4,773  3,269 
                          Gain on sales of real estate  3,871  17,031  4,324 
                          Income taxes  (44)    
                          Minority interests in discontinued operations  (345) (3,817) (1,497)
                            
                           
                           
                           
                          Income from discontinued operations, net of minority interests $1,845 $17,987 $6,096 
                            
                           
                           
                           

                          F-51


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          19. Commitments and Contingencies

                                  In the normal course of business, we are involved in legal actions arising from our ownership and administration of properties. Management does not anticipate that any liabilities that may result will have a materially adverse effect on our financial position, operations or liquidity. We are subject to various Federal, state and local environmental regulations related to our property ownership and operation. We have performed environmental assessments of our properties, the results of which have not revealed any environmental liability that we believe would have a materially adverse effect on our financial position, operations or liquidity.

                          Acquisitions

                                  As of December 31, 2007, we were under contract to acquire a parcel of land in Frederick, Maryland for an expected purchase price of $11,125, on which we had paid a deposit of $80.

                                  We were also obligated to make an additional cash payment of up to $4,000 in a future year in connection with our acquisition of the land at the former Fort Ritchie United States Army base in Cascade, Washington County, Maryland. This payment could be reduced by a range of $750 to the full $4,000 depending on (1) defined levels of job creation resulting from the future development of the property taking place and (2) future real estate taxes generated by the property.

                          Dispositions

                                  As of December 31, 2007, we were under contract to sell five condominium units within the building that was constructed by 13849 Park Center Road, LLC for an aggregate purchase price of $7,475. These sales were completed in January and February 2008.

                          Joint Ventures

                                  As part of our obligations under the partnership agreement of Harrisburg Corporate Gateway Partners, LP, we agreed to indemnify the partnership's lender for 80% of losses under standard nonrecourse loan guarantees (environmental indemnifications and guarantees against fraud and misrepresentation) during the period of time in which we manage the partnership's properties; we do not expect to incur any losses under these loan guarantees.

                                  We are party to a contribution agreement that formed a joint venture relationship with a limited partnership to develop up to 1.8 million square feet of office space on 63 acres of land located in Hanover, Maryland. Under the contribution agreement, we agreed to fund up to $2,200 in pre-construction costs associated with the property. As we and the joint venture partner agree to proceed with the construction of buildings in the future, our joint venture partner would contribute land into newly-formed entities and we would make additional cash capital contributions into such entities to fund development and construction activities for which financing is not obtained. As discussed in Note 5, we obtained a 50% interest in one such joint venture in July 2007.

                                  We may be required to make our pro rata share of additional investments in our real estate joint ventures (generally based on our percentage ownership) in the event that additional funds are needed. In the event that the other members of these joint ventures do not pay their share of investments when additional funds are needed, we may then deem it appropriate to make even larger investments in these joint ventures.

                          F-52


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          19. Commitments and Contingencies (Continued)

                                  In one of the consolidated joint ventures that we owned as of December 31, 2007, we would be obligated to acquire the other member's 50% interest in the joint venture if defined events were to occur. The amount we would need to pay for that membership interest is computed based on the amount that the owner of the interest would receive under the joint venture agreement in the event that office properties owned by the joint venture was sold for a capitalized fair value (as defined in the agreement) on a defined date. We estimate the aggregate amount we would need to pay for the other member's membership interest in this joint venture to be $718; however, since the determination of this amount is dependent on the operations of the office property, which is not both completed and sufficiently occupied, this estimate is preliminary and could be materially different from the actual obligation.

                          Office Space Operating Leases

                                  We are obligated as lessee under five operating leases for office space. Future minimum rental payments due under the terms of these leases as of December 31, 2007 follow:

                          2008 $261
                          2009  176
                          2010  135
                          2011  57
                            
                            $629
                            

                          Other Operating Leases

                                  We are obligated under various leases for vehicles and office equipment. Future minimum rental payments due under the terms of these leases as of December 31, 2007 follow:

                          2008 $507
                          2009  363
                          2010  177
                          2011  42
                            
                            $1,089
                            

                          Environmental Indemnity Agreement

                                  We agreed to provide certain environmental indemnifications in connection with a lease of three properties in our New Jersey region. The prior owner of the properties, a Fortune 100 company which is responsible for groundwater contamination at such properties, previously agreed to indemnify us for (1) direct losses incurred in connection with the contamination and (2) its failure to perform

                          F-53


                          Corporate Office Properties Trust and Subsidiaries

                          Notes to Consolidated Financial Statements (Continued)

                          (Dollars in thousands, except per share data)

                          19. Commitments and Contingencies (Continued)


                          remediation activities required by the State of New Jersey, up to the point that the state declares the remediation to be complete. Under the lease agreement, we agreed to the following:

                            to indemnify the tenant against losses covered under the prior owner's indemnity agreement if the prior owner fails to indemnify the tenant for such losses. This indemnification is capped at $5,000 in perpetuity after the State of New Jersey declares the remediation to be complete;

                            to indemnify the tenant for consequential damages (e.g., business interruption) at one of the buildings in perpetuity and another of the buildings for 15 years after the tenant's acquisition of the property from us, if such acquisition occurs. This indemnification is capped at $12,500; and

                            to pay 50% of additional costs related to construction and environmental regulatory activities incurred by the tenant as a result of the indemnified environmental condition of the properties. This indemnification is capped at $300 annually and $1,500 in the aggregate.

                          F-54


                            Corporate Office Properties Trust and Subsidiaries

                            Notes to Consolidated Financial Statements (Continued)

                            (Dollars in thousands, except per share data)

                            20.    Quarterly data (Unaudited)

                                    The tables below set forth selected quarterly information for the years ended December 31, 2007 and 2006. Certain of the amounts below have been reclassified to conform to our current presentation of discontinued operations, which is discussed in Note 18.

                             
                             For the Year Ended December 31, 2007
                             
                             
                             First Quarter
                             Second Quarter
                             Third Quarter
                             Fourth Quarter
                             
                            Revenues $99,214 $102,335 $105,333 $103,292 
                              
                             
                             
                             
                             
                            Operating income $26,805 $29,772 $31,553 $32,115 
                              
                             
                             
                             
                             
                            Income from continuing operations $5,504 $8,227 $8,448 $9,200 
                              
                             
                             
                             
                             
                            Income from discontinued operations $43 $(511)$1,945 $368 
                              
                             
                             
                             
                             
                            Net income $5,547 $7,877 $11,431 $9,929 
                              
                             
                             
                             
                             
                            Preferred share dividends  (3,993) (4,025) (4,025) (4,025)
                              
                             
                             
                             
                             
                            Net income available to common shareholders $1,554 $3,852 $7,406 $5,904 
                              
                             
                             
                             
                             
                            Basic earnings per share:             
                             Income from continuing operations $0.03 $0.09 $0.12 $0.12 
                              
                             
                             
                             
                             
                             Net income available to common shareholders $0.03 $0.08 $0.16 $0.13 
                              
                             
                             
                             
                             
                            Diluted earnings per share:             
                             Income from continuing operations $0.03 $0.09 $0.11 $0.12 
                              
                             
                             
                             
                             
                             Net income available to common shareholders $0.03 $0.08 $0.15 $0.12 
                              
                             
                             
                             
                             
                             
                             
                             For the Year Ended December 31, 2006
                             
                             
                             First Quarter
                             Second Quarter
                             Third Quarter
                             Fourth Quarter
                             
                            Revenues $85,135 $84,532 $91,660 $92,335 
                              
                             
                             
                             
                             
                            Operating income $25,933 $27,796 $26,981 $27,710 
                              
                             
                             
                             
                             
                            Income from continuing operations $7,277 $8,701 $7,507 $7,023 
                              
                             
                             
                             
                             
                            Income from discontinued operations $2,550 $390 $12,483 $2,564 
                              
                             
                             
                             
                             
                            Net income $9,937 $9,116 $20,587 $9,587 
                            Preferred share dividends  (3,654) (3,653) (4,307) (3,790)
                            Issuance costs associated with redeemed preferred shares      (1,829) (2,067)
                              
                             
                             
                             
                             
                            Net income available to common shareholders $6,283 $5,463 $14,451 $3,730 
                              
                             
                             
                             
                             
                            Basic earnings per share:             
                             Income from continuing operations $0.09 $0.12 $0.05 $0.03 
                              
                             
                             
                             
                             
                             Net income available to common shareholders $0.16 $0.13 $0.34 $0.09 
                              
                             
                             
                             
                             
                            Diluted earnings per share:             
                             Income from continuing operations $0.09 $0.12 $0.04 $0.03 
                              
                             
                             
                             
                             
                             Net income available to common shareholders $0.15 $0.13 $0.33 $0.08 
                              
                             
                             
                             
                             

                            F-55


                            Corporate Office Properties Trust and Subsidiaries

                            Notes to Consolidated Financial Statements (Continued)

                            (Dollars in thousands, except per share data)

                            21.    Pro Forma Financial Information (Unaudited)

                                    We accounted for our acquisitions using the purchase method of accounting. We included the results of operations for our acquisitions in our Consolidated Statements of Operations from their respective purchase dates through December 31, 2007.

                                    We prepared our pro forma condensed consolidated financial information presented below as if the Nottingham Acquisition that took place in 2007 had occurred at the beginning of the respective periods. The pro forma financial information is unaudited and is not necessarily indicative of the results that actually would have occurred if these acquisitions and dispositions had occurred at the beginning of the respective periods, nor does it purport to indicate our results of operations for future periods.

                             
                             For the Years Ended December 31,
                             
                             2007
                             2006
                            Pro forma total revenues $410,993 $387,284
                              
                             
                            Pro forma net income $35,050 $43,621
                              
                             
                            Pro forma net income available to common shareholders $18,949 $22,833
                              
                             
                            Pro forma earnings per common share on net income available to common shareholders      
                             Basic $0.41 $0.51
                              
                             
                             Diluted $0.40 $0.49
                              
                             

                            22.    Subsequent Events

                                    On January 29, 2008, we completed the formation of M Square Associates, LLC, a consolidated joint venture in which we hold a 45% equity interest. This joint venture will own, develop and manage office properties, approved for up to approximately 750,000 square feet, located in M Square Research Park in College Park, Maryland. This joint venture had construction underway on a 118,107 square foot property within M Square Research Park.

                                    On January 29, 2008, we had a 59,763 square foot property in Colorado Springs that was 100% pre-leased become fully operational.

                                    On January 31, 2008, we completed the sale of the 429 Ridge Road property in our Northern/Central New Jersey region for $17,000.

                            F-56


                            Corporate Office Properties Trust
                            Schedule III—Real Estate Depreciation and Amortization
                            December 31, 2007
                            (Dollars in thousands)

                             
                              
                              
                              
                             Initial Cost
                              
                              
                              
                              
                              
                              
                             
                              
                              
                              
                             Costs
                            Capitalized
                            Subsequent to
                            Acquisition

                              
                              
                              
                              
                              
                            Property
                             Location
                             Building Type
                             Encumbrances(1)
                             Land
                             Building
                            and Land
                            Improvements

                             Gross Amounts
                            Carried at
                            Close of Period(7)

                             Accumulated
                            Depreciation

                             Year Built or
                            Renovated

                             Date
                            Acquired

                             Depreciation
                            Life

                            751, 753 760, 785 Jolly Road Blue Bell, PA Office $ $25,374 $91,290 $5 $116,669 $(22,553)1966/1996 10/14/1997 40 Years
                            13200 Woodland Park Drive Herndon, VA Office  70,646  10,428  49,476  13,345  73,249  (15,614)2002 6/2/2003 40 Years
                            7125 Columbia Gateway Drive Columbia, MD Office  37,172  20,487  46,994  1,083  68,564  (2,315)1973/1999 6/29/2006 40 Years
                            1751 Pinnacle Drive McLean, VA Office  33,982  10,486  43,013  9,485  62,984  (5,540)1989/1985 9/23/2004 40 Years
                            15000 Conference Center Drive Chantilly,VA Office  54,000  5,193  47,526  4,527  57,246  (10,398)1989 11/30/2001 40 Years
                            11751 Meadowville Lane Richmond, VA Office  44,000  1,305  52,200    53,505  (751)2007 9/15/2006 40 Years
                            1753 Pinnacle Drive McLean, VA Office  27,077  8,275  34,353  6,967  49,595  (3,641)1976/2004 9/23/2004 40 Years
                            15010 Conference Center Drive Chantilly,VA Office  96,000  3,500  42,233  11  45,744  (1,233)2006 11/30/2001 40 Years
                            2730 Hercules Road Annapolis Junction, MD Office  21,946  8,737  31,612  28  40,377  (7,314)1990 9/28/1998 40 Years
                            8611 Military Drive San Antonio, TX Office    14,020  24,043  7  38,070  (1,325)1982/1985 3/30/2005 40 Years
                            2720 Technology Drive Annapolis Junction, MD Office    3,863  29,279  35  33,177  (2,437)2004 1/31/2002 40 Years
                            322 Sentinel Drive Annapolis Junction, MD Office    2,605  27,839    30,444  (608)2006 11/14/2003 40 Years
                            318 Sentinel Drive Annapolis Junction, MD Office    2,185  27,667    29,852  (1,308)2005 11/14/2003 40 Years
                            302 Sentinel Drive Annapolis Junction, MD Office  22,506  2,648  26,892  5  29,545  (79)2007 11/14/2003 40 Years
                            201 Technology Park Drive Lebanon, VA Office    727  27,909    28,636  (178)2007 10/5/2007 40 Years
                            Clarks 100 Annapolis Junction, MD Office    25,184  3,192    28,376   (2) 6/29/2003 N/A
                            140 National Business Parkway Annapolis Junction, MD Office    3,407  24,167  631  28,205  (2,327)2003 12/31/2003 40 Years
                            304 Sentinel Drive Annapolis Junction, MD Office  37,280  3,411  24,066  17  27,494  (1,165)2006 11/14/2003 40 Years
                            11800 Tech Road Silver Spring, MD Office  17,563  4,574  19,849  2,140  26,563  (4,171)1969/1989 8/1/2002 40 Years
                            11311 McCormick Road Hunt Valley, MD Office    2,308  21,364  1,373  25,045  (1,421)1984/1994 12/22/2005 40 Years
                            15049 Conference Center Drive Chantilly,VA Office  13,669  4,415  20,489  14  24,918  (3,715)1997 8/14/2002 40 Years
                            7468 Candlewood Road Hanover, MD Office    5,599  19,142    24,741   1979/1982(2) 12/20/2005 N/A
                            6711 Columbia Gateway Drive Columbia, MD Office  19,500  2,683  22,016  25  24,724  (577)2006 9/28/2000 40 Years
                            306 Sentinel Drive Annapolis Junction, MD Office    3,260  20,901  21  24,182  (730)2006 11/14/2003 40 Years
                            2711 Technology Drive Annapolis Junction, MD Office  17,343  2,251  21,646  7  23,904  (4,059)2002 11/13/2000 40 Years
                            2900 Towerview Road Herndon, VA Office    4,468  17,454  1,401  23,323  (752)1982(2) 12/20/2005 40 Years
                            7740 Milestone Parkway Hanover, MD Office    3,825  18,228    22,053   (2) 7/2/2007 N/A
                            6731 Columbia Gateway Drive Columbia, MD Office    2,807  18,986  205  21,998  (3,061)2002 3/29/2000 40 Years
                            400 Professional Drive Gaithersburg, MD Office  15,943  3,673  17,399  894  21,966  (3,665)2000 3/5/2004 40 Years
                            320 Sentinel Drive Annapolis Junction, MD Office  18,083  2,068  19,877    21,945  (42)2007 11/14/2003 40 Years
                            7200 Riverwood Drive Columbia, MD Office  15,499  4,089  16,356  1,063  21,508  (4,032)1986 10/13/1998 40 Years
                            Interquest Land Parcel Colorado Springs, CO Office    19,400  2,051    21,451   (2) 9/30/2005 N/A
                            431 Ridge Road Dayton, NJ Office    2,782  11,128  7,323  21,233  (5,485)1958/1998 10/14/1997 40 Years
                            9690 Deereco Road Timonium, MD Office  8,529  3,415  13,723  3,431  20,569  (4,543)1988 12/21/1999 40 Years
                            14280 Park Meadow Drive Chantilly,VA Office  9,194  3,731  16,140  298  20,169  (1,930)1999 9/29/2004 40 Years

                            F-57


                             
                              
                              
                              
                             Initial Cost
                              
                              
                              
                              
                              
                              
                             
                              
                              
                              
                             Costs
                            Capitalized
                            Subsequent to
                            Acquisition

                              
                              
                              
                              
                              
                            Property
                             Location
                             Building Type
                             Encumbrances(1)
                             Land
                             Building
                            and Land
                            Improvements

                             Gross Amounts
                            Carried at
                            Close of Period(7)

                             Accumulated
                            Depreciation

                             Year Built or
                            Renovated

                             Date
                            Acquired

                             Depreciation
                            Life

                            15059 Conference Center Drive Chantilly,VA Office 23,078 5,753 13,816 584 20,153 (3,012)2000 8/14/2002 40 Years
                            10150 York Road Hunt Valley, MD Office  2,700 11,731 5,358 19,789 (2,914)1985 4/15/2004 40 Years
                            14900 Conference Center Drive Chantilly,VA Office 14,199 3,436 14,895 1,370 19,701 (2,811)1999 7/25/2003 40 Years
                            15 West Gude Drive Rockville, MD Office  3,120 13,658 2,892 19,670 (1,307)1986 4/7/2005 40 Years
                            2691 Technology Drive Annapolis Junction, MD Office 24,000 2,098 17,342 5 19,445 (966)2005 11/14/2003 40 Years
                            2721 Technology Drive Annapolis Junction, MD Office 12,831 4,611 14,602 12 19,225 (2,842)2000 10/21/1999 40 Years
                            870 - 880 Elkridge Landing Road Linthicum, MD Office 15,438 2,003 10,403 6,430 18,836 (4,998)1981 8/3/2001 40 Years
                            6950 Columbia Gateway Drive Columbia, MD Office 9,717 3,596 14,269 936 18,801 (3,590)1998 10/21/1998 40 Years
                            45 West Gude Drive Rockville, MD Office  3,102 15,267 36 18,405 (1,551)1987 4/7/2005 40 Years
                            429 Ridge Road Dayton, NJ Office  2,932 11,729 3,274 17,935 (2,946)1966/1996 10/14/1997 40 Years
                            2701 Technology Drive Annapolis Junction, MD Office 13,207 1,737 15,266 11 17,014 (3,052)2001 5/26/2000 40 Years
                            132 National Business Parkway Annapolis Junction, MD Office 10,255 2,917 12,438 1,501 16,856 (3,861)2000 5/28/1997 40 Years
                            13454 Sunrise Valley Drive Herndon, VA Office 11,422 2,899 12,202 1,019 16,120 (2,167)1998 7/25/2003 40 Years
                            133 National Business Parkway Annapolis Junction, MD Office 6,935 2,517 10,234 3,367 16,118 (3,091)1997 9/28/1998 40 Years
                            10001 Franklin Square Drive White Marsh, MD Office  4,033 11,483 550 16,066 (368)1997 1/9/2007 40 Years
                            7000 Columbia Gateway Drive Columbia, MD Office 18,958 3,131 12,103 27 15,261 (1,651)1999 5/31/2002 40 Years
                            110 Thomas Johnson Drive Frederick, MD Office  2,810 12,075 281 15,166 (683)1987/1999 10/21/2005 40 Years
                            1306 Concourse Drive Linthicum, MD Office 9,151 2,796 11,186 1,117 15,099 (2,876)1990 11/18/1999 40 Years
                            2500 Riva Rd Annapolis, MD Office 12,545 2,791 12,185  14,976 (1,664)2000 3/4/2003 40 Years
                            1304 Concourse Drive Linthicum, MD Office 10,551 1,999 12,934 28 14,961 (2,276)2002 11/18/1999 40 Years
                            6940 Columbia Gateway Drive Columbia, MD Office 16,752 3,545 9,916 1,377 14,838 (2,891)1999 11/13/1998 40 Years
                            8621 Robert Fulton Drive Columbia, MD Office 18,235 2,317 12,336 57 14,710 (613)2005 6/10/2005 40 Years
                            5725 Mark Dabling Blvd Colorado Springs, CO Office 12,882 900 11,397 2,104 14,401 (955)1984 5/18/2006 40 Years
                            Fort Ritchie Washington County, MD Mixed-Use  4,798 9,522 79 14,399 (16)Various(2)(6) 10/5/2006 Various(6)
                            6750 Alexander Bell Drive Columbia, MD Office 8,136 1,263 12,460 597 14,320 (3,235)2000 12/31/1998 40 Years
                            200 International Circle Hunt Valley, MD Office  2,016 10,851 1,317 14,184 (683)1987 12/22/2005 40 Years
                            7067 Columbia Gateway Drive Columbia, MD Office 8,516 1,829 11,823 349 14,001 (1,854)2001 8/30/2001 40 Years
                            375 West Padonia Road Timonium, MD Office  2,483 10,448 895 13,826 (2,456)1986 12/21/1999 40 Years
                            135 National Business Parkway Annapolis Junction, MD Office 6,654 2,484 9,750 1,478 13,712 (3,013)1998 12/30/1998 40 Years
                            5775 Mark Dabling Blvd Colorado Springs, CO Office 12,477 1,035 12,440 188 13,663 (1,081)1984 5/18/2006 40 Years
                            4851 Stonecroft Boulevard Chantilly,VA Office 15,887 1,878 11,593 4 13,475 (931)2006 8/14/2002 40 Years
                            985 Space Center Drive Colorado Springs, CO Office  777 12,287 202 13,266 (859)1989 9/28/2005 40 Years
                            141 National Business Parkway Annapolis Junction, MD Office 6,521 2,398 9,590 934 12,922 (2,527)1990 9/28/1998 40 Years
                            Campbell Boulevard and Franklin Square White Marsh, MD Office  12,024 852  12,876  (2) 1/9/2007 N/A
                            22309 Exploration Drive Lexington Park, MD Office 1,154 2,243 10,419 121 12,783 (1,465)1984 3/24/2004 40 Years

                            F-58


                             
                              
                              
                              
                             Initial Cost
                              
                              
                              
                              
                              
                              
                             
                              
                              
                              
                             Costs
                            Capitalized
                            Subsequent to
                            Acquisition

                              
                              
                              
                              
                              
                            Property
                             Location
                             Building Type
                             Encumbrances(1)
                             Land
                             Building
                            and Land
                            Improvements

                             Gross Amounts
                            Carried at
                            Close of Period(7)

                             Accumulated
                            Depreciation

                             Year Built or
                            Renovated

                             Date
                            Acquired

                             Depreciation
                            Life

                            Gateway Exchange III Columbia, MD Office  1,753 10,779  12,532  (2) 9/28/2000 N/A
                            Patriot Park Colorado Springs, CO Office  6,882 5,583  12,465  (2) 7/8/2005 N/A
                            8110 Corporate Drive White Marsh, MD Office  2,285 10,117  12,402 (366)2001 1/9/2007 40 Years
                            655 Space Center Drive Colorado Springs, CO Office  745 11,623  12,368  (2) 7/8/2005 N/A
                            920 Elkridge Landing Road Linthicum, MD Office 7,990 2,101 9,765 328 12,194 (2,717)1982 7/2/2001 40 Years
                            226 Schilling Circle Hunt Valley, MD Office  1,877 9,891 232 12,000 (738)1980 12/22/2005 40 Years
                            5755 Mark Dabling Blvd Colorado Springs, CO Office 10,208 799 10,324 754 11,877 (654)1989 5/18/2006 40 Years
                            8140 Corporate Drive White Marsh, MD Office  2,158 8,457 1,191 11,806 (387)2003 1/9/2007 40 Years
                            134 National Business Parkway Annapolis Junction, MD Office 13,938 3,684 7,516 577 11,777 (2,092)1999 11/13/1998 40 Years
                            1302 Concourse Drive Linthicum, MD Office 6,801 2,078 8,313 1,377 11,768 (2,487)1996 11/18/1999 40 Years
                            900 Elkridge Landing Road Linthicum, MD Office  1,993 7,972 1,438 11,403 (2,691)1982 4/30/1998 40 Years
                            Patriot Park Building 1 Colorado Springs, CO Office  654 10,591  11,245 (320)2006 7/8/2005 40 Years
                            6700 Alexander Bell Drive Columbia, MD Office 4,000 1,755 7,019 2,458 11,232 (2,350)1988 5/14/2001 40 Years
                            131 National Business Parkway Annapolis Junction, MD Office 5,183 1,906 7,623 1,268 10,797 (2,549)1990 9/28/1998 40 Years
                            Northgate Business Park Aberdeen, MD Office  10,409 320  10,729  (2) 9/14/2007 N/A
                            1055 North Newport Road Colorado Springs, CO Office  972 9,753  10,725  (2) 5/19/2006 N/A
                            7160 Riverwood Drive Columbia, MD Office  2,732 7,006 897 10,635 (420)2000 1/10/2007 40 Years
                            1199 Winterson Road Linthicum, MD Office 18,578 1,599 6,395 2,553 10,547 (2,561)1988 4/30/1998 40 Years
                            14850 Conference Center Drive Chantilly,VA Office 8,078 1,615 8,358 4 9,977 (1,718)2000 7/25/2003 40 Years
                            1190 Winterson Road Linthicum, MD Office 11,291 1,335 5,340 3,264 9,939 (3,083)1987 4/30/1998 40 Years
                            999 Corporate Boulevard Linthicum, MD Office 13,533 1,187 8,332 295 9,814 (1,855)2000 8/1/1999 40 Years
                            14840 Conference Center Drive Chantilly,VA Office 8,204 1,572 8,175 15 9,762 (1,821)2000 7/25/2003 40 Years
                            Waterview III Herndon, VA Office  9,614 78  9,692  (3) 4/29/2004 N/A
                            6740 Alexander Bell Drive Columbia, MD Office 4,221 1,424 5,696 2,515 9,635 (2,256)1992 12/31/1998 40 Years
                            Nottingham Ridge White Marsh, MD Office  8,861 742  9,603  (2) 1/9/2007 N/A
                            8031 Corporate Drive White Marsh, MD Office  2,548 6,976  9,524 (245)1988/2004 1/9/2007 40 Years
                            16480 Commerce Dr Dahlgren, VA Office  1,857 7,666  9,523 (799)2004 12/28/2004 40 Years
                            9140 Route 108 Columbia, MD Office  1,637 5,500 2,190 9,327 (1,232)1974/1985 12/14/2000 40 Years
                            7467 Ridge Road Hanover, MD Office 6,120 1,629 6,517 1,069 9,215 (1,992)1990 4/28/1999 40 Years
                            Columbia Gtwy T11 Lot 1 Columbia, MD Office  6,387 2,719  9,106  (2) 9/20/2004 N/A
                            201 International Circle Hunt Valley, MD Office  1,552 6,086 1,348 8,986 (593)1982 12/22/2005 40 Years
                            9965 Federal Drive Colorado Springs, CO Office  1,401 7,417 128 8,946 (66)1983(2) 1/19/2006 40 Years
                            7240 Parkway Drive Hanover, MD Office 4,069 1,496 5,985 1,383 8,864 (1,890)1985 4/18/2000 40 Years
                            849 International Drive Linthicum, MD Office 11,692 1,356 5,426 1,990 8,772 (2,242)1988 2/23/1999 40 Years
                            13450 Sunrise Valley Drive Herndon, VA Office 5,679 1,386 5,576 1,777 8,739 (1,090)1998 7/25/2003 40 Years
                            Parcels 27 and 37A-Westfields Corporate Center Chantilly,VA Office  7,141 1,261  8,402  (3) 1/27/2005 N/A

                            F-59


                             
                              
                              
                              
                             Initial Cost
                              
                              
                              
                              
                              
                              
                             
                              
                              
                              
                             Costs
                            Capitalized
                            Subsequent to
                            Acquisition

                              
                              
                              
                              
                              
                            Property
                             Location
                             Building Type
                             Encumbrances(1)
                             Land
                             Building
                            and Land
                            Improvements

                             Gross Amounts
                            Carried at
                            Close of Period(7)

                             Accumulated
                            Depreciation

                             Year Built or
                            Renovated

                             Date
                            Acquired

                             Depreciation
                            Life

                            Lots 24R-27R & 31RR-32RR, National Business Parkway Annapolis Junction, MD Office   8,340  8,340  (2) 11/14/2003 N/A
                            1099 Winterson Road Linthicum, MD Office 12,012 1,323 5,293 1,649 8,265 (1,863)1988 4/30/1998 40 Years
                            1362 Mellon Road Hanover, MD Office  1,706 6,497  8,203  (2) 2/10/2006 N/A
                            7015 Albert Einstein Drive Columbia, MD Office 3,605 2,058 6,093  8,151 (775)1999 12/1/2005 40 Years
                            5520 Research Park Drive Baltimore, MD Office  102 7,947  8,049  (2) 4/4/2006 N/A
                            502 Washington Avenue Towson, MD Office 5,444 826 7,045 91 7,962 (421)1984 1/9/2007 40 Years
                            6716 Alexander Bell Drive Columbia, MD Office 3,683 1,242 4,969 1,723 7,934 (2,183)1990 12/31/1998 40 Years
                            9910 Franklin Square Drive White Marsh, MD Office 5,762 1,300 6,590  7,890 (242)2005 1/9/2007 40 Years
                            46579 Expedition Drive Lexington Park, MD Office 3,997 1,406 5,943 540 7,889 (903)2002 3/24/2004 40 Years
                            1670 North Newport Road Colorado Springs, CO Office 4,819 853 7,007  7,860 (565)1986/1987 9/30/2005 40 Years
                            16539 & 16541 Commerce Drive Dahlgren, VA Office  1,462 6,132 261 7,855 (911)2004 12/21/2004 40 Years
                            7210 Ambassador Road Woodlawn, MD Office  1,481 6,257 104 7,842 (483)1972 12/22/2005 40 Years
                            7272 Park Circle Dr Hanover, MD Office 5,863 1,479 6,310 48 7,837 (235)1991/1996 1/10/2007 40 Years
                            911 Elkridge Landing Road Linthicum, MD Office  1,215 4,861 1,605 7,681 (1,728)1985 4/30/1998 40 Years
                            7152 Windsor Boulevard Woodlawn, MD Office  879 6,764  7,643 (352)1985 12/22/2005 40 Years
                            22289 Exploration Drive Lexington Park, MD Office 3,884 1,422 5,719 408 7,549 (672)2000 3/24/2004 40 Years
                            San Antonio land parcel—31 acres San Antonio, TX Office  7,430 85  7,515  (3) 1/20/2006 N/A
                            22299 Exploration Drive Lexington Park, MD Office 3,571 1,362 5,814 293 7,469 (878)1998 3/24/2004 40 Years
                            109-111 Allegheny Avenue Towson, MD Office  1,688 5,620 51 7,359 (164)1971 1/9/2007 40 Years
                            46591 Expedition Drive Lexington Park, MD Office  1,200 6,085  7,285 (189)2002 3/24/2004 40 Years
                            891 Elkridge Landing Road Linthicum, MD Office 3,895 1,160 4,792 1,157 7,109 (1,262)1984 7/2/2001 40 Years
                            44425 Pecan Court California, MD Office  1,309 5,458 164 6,931 (735)1997 5/5/2004 40 Years
                            1201 Winterson Road Linthicum, MD Office  1,288 5,154 461 6,903 (1,265)1985 4/30/1998 40 Years
                            8671 Robert Fulton Drive Columbia, MD Office 7,465 1,718 4,280 881 6,879 (810)2003 12/30/2003 40 Years
                            901 Elkridge Landing Road Linthicum, MD Office 3,644 1,151 4,416 1,059 6,626 (1,159)1984 7/2/2001 40 Years
                            7138 Columbia Gateway Drive Columbia, MD Office 5,406 1,104 3,518 1,968 6,590 (566)1990 9/19/2005 40 Years
                            9950 Federal Drive Colorado Springs, CO Office 1,971 877 5,045 589 6,511 (480)2001 12/22/2005 40 Years
                            9920 Franklin Square Drive White Marsh, MD Office  1,109 5,293  6,402 (170)2006 1/9/2007 40 Years
                            7130 Columbia Gateway Drive Columbia, MD Office 6,519 1,350 4,412 448 6,210 (403)1989 9/19/2005 40 Years
                            7150 Riverwood Drive Columbia, MD Office  1,821 4,388  6,209 (166)2000 1/10/2007 40 Years
                            22300 Exploration Drive Lexington Park, MD Office  1,094 5,038 56 6,188 (582)1989 11/9/2004 40 Years
                            4979 Mercantile Road White Marsh, MD Office  1,388 4,783  6,171 (163)1985 1/9/2007 40 Years
                            939 Elkridge Landing Road Linthicum, MD Office  939 3,853 1,325 6,117 (1,550)1983 4/30/1998 40 Years
                            300 Sentinel Drive Annapolis Junction, MD Office  1,480 4,599  6,079  (2) 11/14/2003 N/A
                            6708 Alexander Bell Drive Columbia, MD Office 6,320 897 3,588 1,579 6,064 (1,115)1988 5/14/2001 40 Years

                            F-60


                             
                              
                              
                              
                             Initial Cost
                              
                              
                              
                              
                              
                              
                             
                              
                              
                              
                             Costs
                            Capitalized
                            Subsequent to
                            Acquisition

                              
                              
                              
                              
                              
                            Property
                             Location
                             Building Type
                             Encumbrances(1)
                             Land
                             Building
                            and Land
                            Improvements

                             Gross Amounts
                            Carried at
                            Close of Period(7)

                             Accumulated
                            Depreciation

                             Year Built or
                            Renovated

                             Date
                            Acquired

                             Depreciation
                            Life

                            938 Elkridge Landing Road Linthicum, MD Office 4,436 1,204 4,727 126 6,057 (794)1984 7/2/2001 40 Years
                            8114 Sandpiper Circle White Marsh, MD Office  1,634 4,287 120 6,041 (185)1986 1/9/2007 40 Years
                            8020 Corporate Drive White Marsh, MD Office  2,184 3,818  6,002 (144)1997 1/9/2007 40 Years
                            9020 Mendenhall Court Columbia, MD Office  1,233 4,571 178 5,982 (177)1982/2005 1/9/2007 40 Years
                            940 Elkridge Landing Road Linthicum, MD Office 3,367 1,100 4,696 169 5,965 (461)1984(3) 7/2/2001 40 Years
                            881 Elkridge Landing Road Linthicum, MD Office 11,812 1,034 4,137 742 5,913 (1,188)1986 4/30/1998 40 Years
                            San Antonio Land Parcel San Antonio, TX Office  5,893 20  5,913  (3) 6/14/2005 N/A
                            7941-7949 Corporate Drive White Marsh, MD Office  2,087 3,782  5,869 (166)1996 1/9/2007 40 Years
                            7065 Columbia Gateway Drive Columbia, MD Office 3,207 919 4,222 700 5,841 (1,329)2000 8/30/2001 40 Years
                            8661 Robert Fulton Drive Columbia, MD Office 6,564 1,510 3,764 562 5,836 (638)2003 12/30/2003 40 Years
                            4969 Mercantile Road White Marsh, MD Office  1,308 4,492  5,800 (148)1983 1/9/2007 40 Years
                            7063 Columbia Gateway Drive Columbia, MD Office 3,131 902 4,145 728 5,775 (1,469)2000 8/30/2001 40 Years
                            921 Elkridge Landing Road Linthicum, MD Office  1,044 4,176 532 5,752 (1,384)1983 4/30/1998 40 Years
                            6760 Alexander Bell Drive Columbia, MD Office 2,639 890 3,561 1,284 5,735 (1,549)1991 12/31/1998 40 Years
                            8094 Sandpiper Circle White Marsh, MD Office  1,960 3,742  5,702 (169)1998 1/9/2007 40 Years
                            7142 Columbia Gateway Drive Columbia, MD Office 6,280 1,342 4,252 99 5,693 (502)1994 9/19/2005 40 Years
                            930 International Drive Linthicum, MD Office 8,488 1,013 4,053 555 5,621 (1,194)1986 4/30/1998 40 Years
                            6724 Alexander Bell Drive Columbia, MD Office 10,939 449 5,039 48 5,536 (944)2002 5/14/2001 40 Years
                            7318 Parkway Drive Hanover, MD Office 3,651 972 3,888 656 5,516 (919)1984 4/16/1999 40 Years
                            900 International Drive Linthicum, MD Office 8,008 981 3,922 608 5,511 (1,069)1986 4/30/1998 40 Years
                            8098 Sandpiper Circle White Marsh, MD Office  1,797 3,698  5,495 (136)1998 1/9/2007 40 Years
                            Parcel 3-A, Westfields International Corporate Center Chantilly,VA Office  3,609 1,801  5,410  (3) 7/31/2002 N/A
                            1340 Ashton Road Hanover, MD Office 3,399 905 3,620 815 5,340 (1,257)1989 4/28/1999 40 Years
                            5522 Research Park Drive Catonsville,MD Office   5,323  5,323 (46)(2) 3/8/2006 40 Years
                            4940 Campbell Boulevard White Marsh, MD Office  1,379 3,902 6 5,287 (178)1990 1/9/2007 40 Years
                            9720 Patuxent Woods Columbia, MD Office 2,902 1,701 3,509  5,210 (171)1986/2001 1/9/2007 40 Years
                            11011 McCormick Road Hunt Valley, MD Office  875 3,474 840 5,189 (291)1974 12/22/2005 40 Years
                            7320 Parkway Drive Hanover, MD Office 5,650 905 3,635 579 5,119 (895)1983 4/4/2002 40 Years
                            5325 Nottingham Ridge Road White Marsh, MD Office  816 4,246 54 5,116 (378)2002 1/9/2007 40 Years
                            9930 Franklin Square Drive White Marsh, MD Office  1,137 3,921  5,058 (143)2001 1/9/2007 40 Years
                            Gude Drive Land Rockville, MD Office  3,122 1,833  4,955  (2) 4/7/2005 N/A
                            8615 Ridgely's Choice Drive White Marsh, MD Office  1,078 3,613 217 4,908 (116)2005 1/9/2007 40 Years

                            F-61


                             
                              
                              
                              
                             Initial Cost
                              
                              
                              
                              
                              
                              
                             
                              
                              
                              
                             Costs
                            Capitalized
                            Subsequent to
                            Acquisition

                              
                              
                              
                              
                              
                            Property
                             Location
                             Building Type
                             Encumbrances(1)
                             Land
                             Building
                            and Land
                            Improvements

                             Gross Amounts
                            Carried at
                            Close of Period(7)

                             Accumulated
                            Depreciation

                             Year Built or
                            Renovated

                             Date
                            Acquired

                             Depreciation
                            Life

                            9740 Patuxent Woods Columbia, MD Office 2,691 1,629 3,201  4,830 (139)1986/2001 1/9/2007 40 Years
                            800 International Drive Linthicum, MD Office 8,408 775 3,099 909 4,783 (1,005)1988 4/30/1998 40 Years
                            8007 Corporate Drive White Marsh, MD Office  1,434 3,340  4,774 (174)1995 1/9/2007 40 Years
                            9160 Guilford Road Columbia, MD Office 2,532 665 2,836 1,198 4,699 (900)1984 4/4/2002 40 Years
                            7061 Columbia Gateway Drive Columbia, MD Office 2,528 729 3,347 559 4,635 (847)2000 8/30/2001 40 Years
                            8010 Corporate Drive White Marsh, MD Office  1,349 3,278  4,627 (124)1998 1/9/2007 40 Years
                            4230 Forbes Boulevard Lanham, MD Office  511 4,111  4,622 (859)2003 (4) 40 Years
                            216 Schilling Center Hunt Valley, MD Office  825 3,752 10 4,587 (179)1988/2001 1/10/2007 40 Years
                            7150 Columbia Gateway Drive Columbia, MD Office 4,850 1,032 3,429 122 4,583 (295)1991 9/19/2005 40 Years
                            9960 Federal Drive Colorado Springs, CO Office 4,485 695 3,873  4,568 (225)2001 12/22/2005 40 Years
                            COPT-FD Indian Head, LLC Charles County, MD Office  4,443 112  4,555  (3) 10/23/2006 N/A
                            9940 Franklin Ridge Drive White Marsh, MD Office  1,052 3,424 7 4,483 (127)2000 1/9/2007 40 Years
                            9900 Franklin Ridge Drive White Marsh, MD Office  979 3,467  4,446 (129)1999 1/9/2007 40 Years
                            7170 Riverwood Drive Columbia, MD Office  1,283 3,096  4,379 (110)2000 1/10/2007 40 Years
                            102 West Pennsylvania Avenue Towson, MD Office  1,090 3,199 85 4,374 (165)1968/2001 1/10/2007 40 Years
                            21 Governor's Court Woodlawn, MD Office  771 3,348 229 4,348 (287)1981/1995 12/22/2005 40 Years
                            9140 Guilford Road Columbia, MD Office 2,933 794 3,261 272 4,327 (727)1983 4/4/2002 40 Years
                            5355 Nottingham Ridge Road White Marsh, MD Office  761 3,562  4,323 (89)2005 1/9/2007 40 Years
                            44408 Pecan Court California, MD Office  817 3,269 85 4,171 (311)1986 3/24/2004 40 Years
                            5020 Campbell Blvd White Marsh, MD Office  1,014 3,136  4,150 (122)1986-1988 1/9/2007 40 Years
                            9730 Patuxent Woods Columbia, MD Office 2,246 1,318 2,714 8 4,040 (145)1986/2001 1/9/2007 40 Years
                            1915 Aerotech Drive Colorado Springs, CO Office 3,394 556 3,094 318 3,968 (253)1985 6/8/2006 40 Years
                            9700 Patuxent Woods Columbia, MD Office 2,200 1,329 2,621 7 3,957 (119)1986/2001 1/9/2007 40 Years
                            1334 Ashton Road Hanover, MD Office 2,766 736 2,946 270 3,952 (739)1989 4/28/1999 40 Years
                            23535 Cottonwood Parkway California, MD Office  763 3,051 17 3,831 (287)1984 3/24/2004 40 Years
                            47 Commerce Drive Cranbury, NJ Office  756 3,026  3,782 (694)1992/1998 10/30/1998 40 Years
                            437 Ridge Road Dayton, NJ Office  717 2,866 175 3,758 (760)1962/1996 10/14/1997 40 Years
                            8029 Corporate Drive White Marsh, MD Office  965 2,720  3,685 (105)1988/2004 1/9/2007 40 Years
                            Gude Drive Land Rockville, MD Office  3,122 542  3,664  (3) 4/7/2005 N/A
                            1925 Aerotech Drive Colorado Springs, CO Office 3,717 556 3,067 3 3,626 (184)1985 6/8/2006 40 Years
                            7939 Honeygo Boulevard White Marsh, MD Office  869 2,735  3,604 (159)1984 1/10/2007 40 Years
                            312 Sentinel Drive Annapolis Junction, MD Office  3,160 432  3,592  (2) 11/14/2003 N/A
                            7253 Ambassador Road Woodlawn, MD Office  792 2,778  3,570 (218)1988 12/22/2005 40 Years
                            Nottingham Road and Philadelphia Avenue White Marsh, MD Office  3,226 220  3,446  (2) 1/9/2007 N/A

                            F-62


                             
                              
                              
                              
                             Initial Cost
                              
                              
                              
                              
                              
                              
                             
                              
                              
                              
                             Costs
                            Capitalized
                            Subsequent to
                            Acquisition

                              
                              
                              
                              
                              
                            Property
                             Location
                             Building Type
                             Encumbrances(1)
                             Land
                             Building
                            and Land
                            Improvements

                             Gross Amounts
                            Carried at
                            Close of Period(7)

                             Accumulated
                            Depreciation

                             Year Built or
                            Renovated

                             Date
                            Acquired

                             Depreciation
                            Life

                            114 National Business Parkway Annapolis Junction, MD Retail  364 3,060 3 3,427 (444)2002 6/30/2000 40 Years
                            224 Schilling Circle Hunt Valley, MD Office  734 2,487 140 3,361 (182)1978/1997 1/10/2007 40 Years
                            Interquest Hybrid 1 Colorado Springs, CO Office  1,854 1,478  3,332  (2) 9/30/2005 N/A
                            5024 Campbell Blvd White Marsh, MD Office  767 2,470 94 3,331 (161)1986-1988 1/9/2007 40 Years
                            8133 Perry Hall Boulevard White Marsh, MD Office  850 2,452 8 3,310 (130)1988 1/10/2007 40 Years
                            222 Schilling Circle Hunt Valley, MD Office  754 2,476 10 3,240 (108)1978/1997 1/10/2007 40 Years
                            16442 Commerce Drive Dahlgren, VA Office 2,452 613 2,582  3,195 (265)2005 12/21/2004 40 Years
                            San.Antonio Visitor Control San Antonio, TX Office   3,178  3,178  (2) 3/30/2005 N/A
                            316 Sentinel Drive Annapolis Junction, MD Office  2,769 387  3,156  (2) 11/14/2003 N/A
                            1331 Ashton Road Hanover, MD Office 2,204 587 2,347 106 3,040 (524)1989 4/28/1999 40 Years
                            Corporate Place IV White Marsh, MD Office  2,017 913  2,930  (2) 1/9/2007 N/A
                            Interquest Epic One Colorado Springs, CO Office  1,840 1,041  2,881  (2) 9/30/2005 N/A
                            7125 Ambassador Road Woodlawn, MD Office  844 1,896 136 2,876 (245)1985 12/22/2005 40 Years
                            5026 Campbell Blvd White Marsh, MD Office  700 2,139  2,839 (85)1986-1988 1/9/2007 40 Years
                            310 Sentinel Drive Annapolis Junction, MD Office  2,393 381  2,774  (2) 11/14/2003 N/A
                            16501 Commerce Drive Dahlgren, VA Office 2,085 522 2,194 38 2,754 (285)2006 12/21/2004 40 Years
                            7923 Honeygo Boulevard White Marsh, MD Office  715 1,932 62 2,709 (102)1985 1/10/2007 40 Years
                            7175 Riverwood Drive Columbia, MD Office  1,788 913  2,701 (46)1996(3) 7/27/2005 40 Years
                            980 Technology Court Colorado Springs, CO Office  526 2,046 124 2,696 (197)1995 9/28/2005 40 Years
                            7134 Columbia Gateway Drive Columbia, MD Office 2,949 704 1,971 7 2,682 (185)1990 9/19/2005 40 Years
                            308 Sentinel Drive Annapolis Junction, MD Office  1,387 1,219  2,606  (2) 11/14/2003 N/A
                            8019 Corporate Drive White Marsh, MD Office 1,717 684 1,898 (4)2,578 (86)1990 1/9/2007 40 Years
                            5022 Campbell Blvd White Marsh, MD Office  624 1,935 11 2,570 (82)1986-1988 1/9/2007 40 Years
                            Clarks Hundred II Annapolis Junction, MD Office  2,409 132  2,541  (2) 3/14/2007 N/A
                            8013 Corporate Drive White Marsh, MD Office 1,615 642 1,788 107 2,537 (398)1990 1/9/2007 40 Years
                            44417 Pecan Court California, MD Office  434 1,939 13 2,386 (341)1989 3/24/2004 40 Years
                            10270 Old Columbia Road Columbia, MD Office 1,215 751 1,430 163 2,344 (85)1988/2001 1/9/2007 40 Years
                            Interquest Hybrid 2 Colorado Springs, CO Office  1,129 1,173  2,302  (2) 9/30/2005 N/A
                            8003 Corporate Drive White Marsh, MD Office  611 1,632 36 2,279 (72)1999 1/9/2007 40 Years
                            16543 Commerce Drive Dahlgren, VA Office 1,739 436 1,830  2,266 (219)2002 12/21/2004 40 Years
                            10280 Old Columbia Road Columbia, MD Office 1,226 756 1,445 59 2,260 (80)1988/2001 1/9/2007 40 Years
                            1350 Dorsey Road Hanover, MD Office 1,477 393 1,573 291 2,257 (522)1989 4/28/1999 40 Years
                            8023 Corporate Drive White Marsh, MD Office 1,499 651 1,603  2,254 (44)1990 1/9/2007 40 Years
                            1460 Dorsey Road Hanover, MD Office  2,141 37  2,178  (3) 2/28/2006 N/A

                            F-63


                             
                              
                              
                              
                             Initial Cost
                              
                              
                              
                              
                              
                              
                             
                              
                              
                              
                             Costs
                            Capitalized
                            Subsequent to
                            Acquisition

                              
                              
                              
                              
                              
                            Property
                             Location
                             Building Type
                             Encumbrances(1)
                             Land
                             Building
                            and Land
                            Improvements

                             Gross Amounts
                            Carried at
                            Close of Period(7)

                             Accumulated
                            Depreciation

                             Year Built or
                            Renovated

                             Date
                            Acquired

                             Depreciation
                            Life

                            Corporate Place III White Marsh, MD Office  2,017 138  2,155  (2) 1/9/2007 N/A
                            44414 Pecan Court California, MD Office  405 1,619 90 2,114 (185)1986 3/24/2004 40 Years
                            11101 McCormick Road Hunt Valley, MD Office  991 1,080 8 2,079 (96)1976 12/22/2005 40 Years
                            314 Sentinel Drive Annapolis Junction, MD Office  1,232 816  2,048  (2) 11/14/2003 N/A
                            1344 Ashton Road Hanover, MD Office 1,334 355 1,421 266 2,042 (495)1989 4/28/1999 40 Years
                            9710 Patuxent Woods Columbia, MD Office 1,068 648 1,269 49 1,966 (53)1986/2001 1/9/2007 40 Years
                            9150 Guilford Road Columbia, MD Office 1,210 319 1,354 235 1,908 (363)1984 4/4/2002 40 Years
                            Riverwood II Columbia, MD Office  1,367 531  1,898  (2) 7/27/2005 N/A
                            1341 Ashton Road Hanover, MD Office 1,149 306 1,223 362 1,891 (377)1989 4/28/1999 40 Years
                            44420 Pecan Court California, MD Office  344 1,374 86 1,804 (117)1989 11/9/2004 40 Years
                            Thomas Johnson Drive Land Frederick, MD Office  1,092 667  1,759  (2) 10/21/2005 N/A
                            100 West Pennsylvania Avenue Towson, MD Office  698 975 30 1,703 (52)1952/1989 1/9/2007 40 Years
                            324 Sentinel Drive Annapolis Junction, MD Office  1,650 28  1,678  (2) 6/29/2003 N/A
                            White Marsh Commerce Center II White Marsh, MD Office  1,613 10  1,623  (3) 1/9/2007 N/A
                            7104 Ambassador Road Woodlawn, MD Office  572 613 410 1,595 (102)1988 12/22/2005 40 Years
                            8015 Corporate Drive White Marsh, MD Office 1,040 446 1,118  1,564 (46)1990 1/9/2007 40 Years
                            15 Governor's Court Woodlawn, MD Office  383 1,168  1,551 (95)1981 12/22/2005 40 Years
                            10290 Old Columbia Road Columbia, MD Office 772 490 895 33 1,418 (34)1988/2001 1/9/2007 40 Years
                            525 Babcock Rd Colorado Springs, CO Office  355 974  1,329 (19)1967 7/12/2007 40 Years
                            Patriot Park VII Colorado Springs, CO Office  644 667  1,311  (2) 7/8/2005 N/A
                            9130 Guilford Road Columbia, MD Office 871 230 975 101 1,306 (230)1984 4/4/2002 40 Years
                            Aerotech 2 Colorado Springs, CO Office  1,291   1,291  (3) 5/19/2006 N/A
                            Lot 401-White Marsh White Marsh, MD Office  1,182 7  1,189  (3) 1/9/2007 N/A
                            6741 Columbia Gateway Drive Columbia, MD Office  675 433  1,108  (2) 9/28/2000 N/A
                            Dahlgren Land Parcel Dahlgren, VA Office  910 160  1,070  (3) 3/16/2005 N/A
                            7129 Ambassador Road Woodlawn, MD Office  129 610 329 1,068 (74)1985 12/22/2005 40 Years
                            0 Galley Road Colorado Springs, CO Office  1,060   1,060  (3) 4/21/2006 N/A
                            Philadelphia Road & Route 43 White Marsh, MD Office  1,008 44  1,052  (3) 1/9/2007 N/A
                            1343 Ashton Road Hanover, MD Office 726 193 774 40 1,007 (169)1989 4/28/1999 40 Years
                            16442A Commerce Drive Dahlgren, VA Office  317 630  947  (2) 12/21/2004 N/A
                            Babcock Development Land Parcel Colorado Springs, CO Office  826   826  (3) 7/1/2007 N/A

                            F-64


                             
                              
                              
                              
                             Initial Cost
                              
                              
                              
                              
                              
                              
                             
                              
                              
                              
                             Costs
                            Capitalized
                            Subsequent to
                            Acquisition

                              
                              
                              
                              
                              
                            Property
                             Location
                             Building Type
                             Encumbrances(1)
                             Land
                             Building
                            and Land
                            Improvements

                             Gross Amounts
                            Carried at
                            Close of Period(7)

                             Accumulated
                            Depreciation

                             Year Built or
                            Renovated

                             Date
                            Acquired

                             Depreciation
                            Life

                            Expedition VII Lexington Park, MD Office    705  102    807   (3) 3/24/2004 N/A
                            17 Governor's Court Woodlawn, MD Office    170  530  102  802  (29)1981 12/22/2005 40 Years
                            7127 Ambassador Road Woodlawn, MD Office    142  455  203  800  (29)1985 12/22/2005 40 Years
                            Park Center Chantilly,VA Office      789    789   (3) 7/18/2002 N/A
                            7131 Ambassador Road Woodlawn, MD Office    105  368  282  755  (27)1985 12/22/2005 40 Years
                            Airport Square XXII Linthicum, MD Office    630  8    638   (3) 12/19/2001 N/A
                            South Brunswick, LP Dayton, NJ Office      591    591   (3) 10/14/1997 N/A
                            7106 Ambassador Road Woodlawn, MD Office    229  306    535  (26)1988 12/22/2005 40 Years
                            Arundel Preserve-Parcel 9 Hanover, MD Office      533    533   (2) (5) N/A
                            COPT Princeton South Dayton, NJ Office    512      512   (3) 9/29/2004 N/A
                            37 Allegheny Avenue Towson, MD Office    504      504   (3) 1/9/2007 N/A
                            7102 Ambassador Road Woodlawn, MD Office    277  203    480  (10)1988 12/22/2005 40 Years
                            9965 Federal Land Parcel Colorado Springs, CO Office    466      466   (3) 1/19/2006 N/A
                            7865 Brock Bridge Rd Annapolis Junction, MD Office    441  24    465   (2) 4/2/2007 N/A
                            7108 Ambassador Road Woodlawn, MD Office    171  252  3  426  (13)1988 12/22/2005 40 Years
                            COPT Pennlyn LLC Blue Bell, PA Office    401      401   (3) 7/14/2004 N/A
                            Arundel Preserve-Parcel 7 Hanover, MD Office      393    393   (2) (5) N/A
                            7873 Brock Bridge Rd Annapolis Junction, MD Office    309  35    344   (2) 3/30/2007 N/A
                            Arundel Presserve-Parcel 8 Hanover, MD Office      264    264   (2) (5) N/A
                            7800 Milestone Parkway Hanover, MD Office      177    177   (2) (5) N/A
                            1338 Ashton Road Hanover, MD Retail  38  50    40  90  (12)1989 4/28/1999 40 Years
                            Other Developments, including intercompany eliminations Various Various    9  (395) 242  (144) 49 Various Various Various
                                  
                             
                             
                             
                             
                             
                                  
                                  $1,262,487 $631,407 $2,103,893 $156,559 $2,891,859 $(288,387)     
                                  
                             
                             
                             
                             
                             
                                  

                            (1)
                            Excludes our unsecured Revolving Credit Facility of $361,000, unsecured notes payable of $1,702, and net premiums on the remaining loans of $653.

                            (2)
                            Under construction, development or redevelopment at December 31, 2007.

                            (3)
                            Held for future development or redevelopment at December 31, 2007.

                            (4)
                            This joint venture was consolidated effective March 31, 2004 as required under FIN 46(R). See Note 2 to our Consolidated Financial Statements for a discussion of FIN 46(R).

                            (5)
                            Development in progress in anticipation of acquisition.

                            (6)
                            Includes residential housing units and a commercial building with depreciable lives of 40 years, as well as commercial assets under development.

                            (7)
                            The aggregate cost of these assets for Federal income tax purposes is approximately $2.4 billion at December 31, 2007.

                            F-65


                                    The following table summarizes our changes in cost of properties for the periods ended December 31, 2007, 2006 and 2005 (in thousands):

                             
                             2007
                             2006
                             2005
                             
                            Beginning balance $2,330,884 $2,061,590 $1,685,016 
                            Property acquisitions  354,972  166,416  341,911 
                            Building and land improvements  226,618  173,746  139,424 
                            Sales  (21,079) (70,868) (28,109)
                            Contribution of assets to unconsolidated joint venture      (76,183)
                            Reclassification of building out of (into) development  464    (464)
                            Other      (5)
                              
                             
                             
                             
                            Ending balance $2,891,859 $2,330,884 $2,061,590 
                              
                             
                             
                             

                                    The following table summarizes our changes in accumulated depreciation for the same time periods (in thousands):

                             
                             2007
                             2006
                             2005
                             
                            Beginning balance $219,574 $174,935 $141,716 
                            Depreciation expense  70,537  55,382  48,421 
                            Sales  (2,162) (10,743) (3,508)
                            Contribution of assets to unconsolidated joint venture      (11,146)
                            Reclassification of building out of (into) development  464    (464)
                            Other  (26)   (84)
                              
                             
                             
                             
                            Ending balance $288,387 $219,574 $174,935 
                              
                             
                             
                             

                            F-66




                            QuickLinks

                            Table of Contents Form 10-K
                            FORWARD-LOOKING STATEMENTS
                            PART I
                            PART II
                            Corporate Office Properties Trust and Subsidiaries (in thousands, except per share data and number of properties)
                            PART III
                            PART IV
                            SIGNATURES
                            CORPORATE OFFICE PROPERTIES TRUST AND SUBSIDIARIES INDEX TO FINANCIAL STATEMENTS
                            Management's Report On Internal Control Over Financial Reporting
                            Report of Independent Registered Public Accounting Firm
                            Corporate Office Properties Trust and Subsidiaries Consolidated Balance Sheets (Dollars in thousands)
                            Corporate Office Properties Trust and Subsidiaries Consolidated Statements of Operations (Dollars in thousands, except per share data)
                            Corporate Office Properties Trust and Subsidiaries Consolidated Statements of Shareholders' Equity (Dollars in thousands)
                            Corporate Office Properties Trust and Subsidiaries Consolidated Statements of Cash Flows (Dollars in thousands)
                            Corporate Office Properties Trust and Subsidiaries Notes to Consolidated Financial Statements (Dollars in thousands, except per share data)