Lexicon Pharmaceuticals
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Lexicon Pharmaceuticals - 10-K annual report


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

FORM 10-K

(MARK ONE)

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

FOR THE FISCAL YEAR ENDED DECEMBER 31, 2005

OR

[ ] 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: 000-30111

LEXICON GENETICS INCORPORATED
(Exact Name of Registrant as Specified in its Charter)

<TABLE>
<S> <C>
DELAWARE 76-0474169
(State or Other Jurisdiction of (I.R.S. Employer
Incorporation or Organization) Identification Number)
</TABLE>

<TABLE>
<S> <C>
8800 TECHNOLOGY FOREST PLACE (281) 863-3000
THE WOODLANDS, TEXAS 77381 (Registrant's Telephone Number,
(Address of Principal Executive Including Area Code)
Offices and Zip Code)
</TABLE>

SECURITIES REGISTERED PURSUANT TO SECTION 12(b) OF THE ACT: NONE

SECURITIES REGISTERED PURSUANT TO SECTION 12(g) OF THE ACT:
Common Stock, par value $0.001 per share

Indicate by check mark if the registrant is a well-known seasoned issuer,
as defined in Rule 405 of the Securities Act of 1933. Yes [ ] No [X]

Indicate by check mark if the registrant is not required to file reports
pursuant to Section 13 or Section 15(d) of the Securities Exchange Act of 1934.
Yes [ ] No [X]

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. Yes [X] 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. [X]

Indicate by check mark whether the registrant is a large accelerated filer,
an accelerated filer or a non-accelerated filer. See definition of "accelerated
filer and large accelerated filer" in Rule 12b-2 of the Securities Exchange Act
of 1934. (check one): Large accelerated filer [ ] Accelerated filer [X]
Non-accelerated filer [ ]

Indicate by check mark whether the registrant is a shell company (as
defined in Rule 12b-2 of the Securities Exchange Act of 1934). Yes [ ] No [X]

The aggregate market value of voting stock held by non-affiliates of the
registrant as of the last day of the registrant's most recently completed second
quarter was approximately $261.9 million, based on the closing price of the
common stock on the Nasdaq National Market on June 30, 2005 of $4.94 per share.
For purposes of the preceding sentence only, all directors, executive officers
and beneficial owners of ten percent or more of the registrant's common stock
are assumed to be affiliates. As of February 28, 2006, 64,559,340 shares of
common stock were outstanding.

DOCUMENTS INCORPORATED BY REFERENCE

Certain sections of the registrant's definitive proxy statement relating to
the registrant's 2006 annual meeting of stockholders, which proxy statement will
be filed under the Securities Exchange Act of 1934 within 120 days of the end of
the registrant's fiscal year ended December 31, 2005, are incorporated by
reference into Part III of this annual report on Form 10-K.

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LEXICON GENETICS INCORPORATED

TABLE OF CONTENTS

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<CAPTION>
ITEM
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<S> <C>
PART I

1. Business............................................................... 1
2. Properties............................................................. 19
3. Legal Proceedings...................................................... 19
4. Submissions of Matters to a Vote of Security Holders................... 19

PART II

5. Market for Registrant's Common Equity and Related Stockholder
Matters................................................................ 20
6. Selected Financial Data................................................ 21
7. Management's Discussion and Analysis of Financial Condition and
Results of Operations.................................................. 22
7A. Quantitative and Qualitative Disclosure About Market Risk.............. 29
8. Financial Statements and Supplementary Data............................ 29
9. Changes in and Disagreements with Accountants on Accounting and
Financial Disclosure................................................... 29
9A. Controls and Procedures................................................ 29

PART III

10. Directors and Executive Officers of the Registrant..................... 31
11. Executive Compensation................................................. 31
12. Security Ownership of Certain Beneficial Owners and Management and
Related Stockholder Matters............................................ 31
13. Certain Relationships and Related Transactions......................... 31
14. Principal Accounting Fees and Services................................. 31

PART IV

15. Exhibits and Financial Statement Schedules............................. 32

Signatures................................................................. 35
</TABLE>

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The Lexicon name and logo, LexVision(R) and OmniBank(R) are registered
trademarks and Genome5000(TM) and e-Biology(TM) are trademarks of Lexicon
Genetics Incorporated.

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In this annual report on Form 10-K, "Lexicon Genetics," "Lexicon," "we,"
"us" and "our" refer to Lexicon Genetics Incorporated.

----------

FACTORS AFFECTING FORWARD LOOKING STATEMENTS

This annual report on Form 10-K contains forward-looking statements. These
statements relate to future events or our future financial performance. We have
attempted to identify forward-looking statements by terminology including
"anticipate," "believe," "can," "continue," "could," "estimate," "expect,"
"intend," "may," "plan," "potential," "predict," "should" or "will" or the
negative of these terms or other comparable terminology. These statements are
only predictions and involve known and unknown risks, uncertainties and other
factors, including the risks outlined under "Item 1. Business - Risk Factors,"
that may cause our or our industry's actual results, levels of activity,
performance or achievements to be materially different from any future results,
levels of activity, performance or achievements expressed or implied by these
forward-looking statements.

Although we believe that the expectations reflected in the forward-looking
statements are reasonable, we cannot guarantee future results, levels of
activity, performance or achievements. We are not under any duty to update any
of the forward-looking statements after the date of this annual report on Form
10-K to conform these statements to actual results, unless required by law.
PART I

ITEM 1. BUSINESS

OVERVIEW

Lexicon Genetics is a biopharmaceutical company focused on the discovery
and development of breakthrough treatments for human disease. We are
systematically discovering the physiological and behavioral functions of genes
to identify those that encode potential targets for therapeutic intervention, or
drug targets. We make these discoveries using our proprietary technology to
knock out, or disrupt, the function of genes in mice to model the effects on
physiology that could be expected from prospective drugs directed against those
targets. For targets that we believe have high pharmaceutical value, we engage
in programs for the discovery and development of potential small molecule,
antibody and protein drugs. We focus our discovery efforts in six therapeutic
areas - diabetes and obesity, cardiovascular disease, psychiatric and
neurological disorders, cancer, immune system disorders and ophthalmic disease -
and we have advanced targets into drug discovery programs in each of these areas
with potential for addressing large medical markets.

The scope of our gene knockout technology, combined with the size and
sophistication of our facilities and our evaluative technologies, provides us
with what we believe to be a significant competitive advantage. We are using
these technologies in our Genome5000 program to discover the physiological and
behavioral functions of 5,000 genes from the human genome that belong to gene
families that we consider to be pharmaceutically important. We have completed
our analysis of more than 60% of these genes, and we expect to complete the
analysis of the remaining genes by the end of 2008. Through the end of 2005, we
had identified and validated in living mammals, or in vivo, more than 90 targets
with promising profiles for drug discovery. As of February 28, 2006, we had
advanced compounds for two of these targets into preclinical development and had
advanced compounds from drug discovery programs for a number of additional
targets into preclinical research. To date, none of our programs has yet
advanced into clinical development.

We are working both independently and through strategic collaborations and
alliances to commercialize our technology and turn our discoveries into drugs.
We have established multiple collaborations with leading pharmaceutical and
biotechnology companies, as well as research institutes and academic
institutions. We are working with Bristol-Myers Squibb Company to discover and
develop novel small molecule drugs in the neuroscience field. We are working
with Genentech, Inc. to discover the functions of secreted proteins and
potential antibody targets identified through Genentech's internal drug
discovery research, and to develop new biotherapeutic drugs based on certain
targets selected from the alliance. We are working with N.V. Organon to
discover, develop and commercialize new biotherapeutic drugs based on another
group of secreted proteins and potential antibody targets. We are working with
Takeda Pharmaceutical Company Limited for the discovery of new drugs for the
treatment of high blood pressure. In addition, we have established
collaborations and license agreements with other leading pharmaceutical and
biotechnology companies under which we receive fees and, in some cases, are
eligible to receive milestone and royalty payments, in return for granting
access to some of our technologies and discoveries for use in such companies'
own drug discovery efforts.

Lexicon Genetics was incorporated in Delaware in July 1995, and commenced
operations in September 1995. Our corporate headquarters are located at 8800
Technology Forest Place, The Woodlands, Texas 77381, and our telephone number is
(281) 863-3000.

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 Securities Exchange Act of 1934 are made
available free of charge on our corporate website located at
www.lexicon-genetics.com as soon as reasonably practicable after the filing of
those reports with the Securities and Exchange Commission. Information found on
our website should not be considered part of this annual report on Form 10-K.

OUR DRUG DISCOVERY PROCESS

Our drug discovery process begins with our Genome5000 program, in which we
are using our gene knockout technology to discover the physiological and
behavioral functions of 5,000 human genes through analysis of the corresponding
knockout mouse models. Our Genome5000 efforts are focused on the discovery of
the functions in mammalian physiology of proteins encoded by gene families that
we consider to be pharmaceutically important, such as G-protein coupled, or
GPCRs, and other receptors, kinases, ion channels, other key enzymes and


1
secreted proteins. We have already completed our physiology- and behavior-based
analysis of more than 60% of these 5,000 genes, and we expect to complete the
analysis of the remaining genes by the end of 2008.

We use knockout mice - mice whose DNA has been altered to disrupt, or knock
out, the function of the altered gene - to discover the physiological and
behavioral effects that result from loss of functioning protein encoded by the
disrupted gene. The study of the effects of knocking out genes in mice has
historically proven to be a powerful tool for understanding human genes because
of the close similarity of gene function and physiology between mice and humans,
with approximately 99% of all human genes having a counterpart in the mouse
genome. Our patented gene trapping and gene targeting technologies enable us to
rapidly generate these knockout mice by altering the DNA of genes in a special
variety of mouse cells, called embryonic stem cells, which can be cloned and
used to generate mice with the altered gene. We employ an integrated platform of
advanced medical technologies to systematically discover, in vivo, the
physiological and behavioral functions and pharmaceutical utility of the genes
we have knocked out and the potential drug targets encoded by the corresponding
human genes.

We believe that our medical center approach and the technology platform
that makes it possible provide us with substantial advantages over other
approaches to discover gene function and identify novel drug targets. In
particular, we believe that the comprehensive nature of this approach allows us
to uncover functions within the context of mammalian physiology that might be
missed by more narrowly focused efforts. We also believe our approach is more
likely to reveal those side effects that may be a direct result of inhibiting or
otherwise modulating the drug target and may limit the utility of potential
therapeutics directed at the drug target. We believe these advantages will
contribute to better target selection and, therefore, to the success of our drug
discovery and development efforts.

The value of our technology has been described in a large body of
scientific literature which was summarized in a retrospective analysis that we
performed of the 100 best selling drugs of 2001 and their targets, as modeled by
the physiological characteristics of knockout mice. This analysis was published
in the January 2003 issue of Nature Reviews Drug Discovery, a peer-reviewed
scientific journal. In this analysis we concluded that in most cases there was a
direct correlation between the physiological characteristics, or phenotypes, of
knockout mice and the therapeutic effect of the 100 best-selling drugs of 2001.

We are working to discover potential small molecule, antibody and protein
drugs for those in vivo-validated drug targets that we consider to have high
pharmaceutical value. We have established internal small molecule drug discovery
capabilities, in which we use our own sophisticated libraries of drug-like
chemical compounds in high-throughput screening assays to identify "hits," or
chemical compounds demonstrating activity, against these targets. We then employ
medicinal chemistry efforts to optimize the potency and selectivity of these
hits and to identify lead compounds for potential development. We have also
established internal antibody and protein drug discovery capabilities, in which
we use protein expansion and antibody technologies to generate and optimize
molecules with appropriate characteristics for development.

In all of our drug discovery programs, we use the same physiological
analysis technology platform that we use in the discovery of gene function to
analyze the in vivo efficacy and safety profiles of drug candidates in mice. Our
physiology-based approach to understanding gene function and our use of mouse
models in our drug discovery efforts allow us to make highly informed decisions
throughout the drug discovery and development process, which we believe may
increase our likelihood of success in discovering breakthrough therapeutics.

OUR LEAD DRUG DISCOVERY PROGRAMS

We have advanced two of our drug discovery programs into preclinical
development in preparation for regulatory filings for the commencement of
clinical trials.

- LX-6171 is a novel small molecule compound with potential for treating
cognitive disorders such as Alzheimer's disease.

- LX-1031 is a novel small molecule compound with potential for treating
irritable bowel syndrome.

We have advanced compounds from drug discovery programs for a number of
additional targets into preclinical research.


2
OUR TECHNOLOGY

The scope of our gene knockout and evaluative technologies allows us to
create and analyze knockout mice at a rate and on a scale that we believe is
unmatched by our competitors. The core elements of our technology platform
include our patented technologies for the generation of knockout mice, our
integrated platform of advanced medical technologies for the systematic and
comprehensive biological analysis of in vivo physiology and our industrialized
approach to medicinal chemistry and the generation of high-quality, drug-like
compound libraries.

GENE KNOCKOUT TECHNOLOGIES

Gene Targeting. Our gene targeting technology, which is covered by nine
issued patents that we have licensed, enables us to generate highly specific
alterations in targeted genes. The technology replaces DNA of a gene in a mouse
embryonic stem cell through a process known as homologous recombination to
disrupt the function of the targeted gene, permitting the generation of knockout
mice. By using this technology in combination with one or more additional
technologies, we are able to generate alterations that selectively disrupt, or
conditionally regulate, the function of the targeted gene for the analysis of
the gene's function in selected tissues, at selected stages in the animal's
development or at selected times in the animal's life. We can also use this
technology to replace the targeted gene with its corresponding human gene for
use for preclinical research in our therapeutic discovery programs.

Gene Trapping. Our gene trapping technology, which is covered by nine
issued patents that we own, is a high-throughput method of generating knockout
mouse clones that we invented. The technology uses genetically engineered
retroviruses that infect mouse embryonic stem cells in vitro, integrate into the
chromosome of the cell and disrupt the function of the gene into which it
integrates, permitting the generation of knockout mice. This process also
stimulates transcription of a non-protein producing portion of the trapped gene,
using the cell's own splicing machinery to extract this transcript from the
chromosome for automated DNA sequencing. This allows us to identify and
catalogue each embryonic stem cell clone by DNA sequence from the trapped gene
and to select embryonic stem cell clones by DNA sequence for the generation of
knockout mice. We have used our gene trapping technology in an automated process
to create our OmniBank library of more than 270,000 frozen gene knockout
embryonic stem cell clones, each identified by DNA sequence in a relational
database. We estimate that our OmniBank library currently contains embryonic
stem cell clones representing more than half of all genes in the mammalian
genome and believe it is the largest library of its kind.

PHYSIOLOGICAL ANALYSIS TECHNOLOGIES

We employ an integrated platform of advanced analytical technologies to
rapidly and systematically discover the physiological and behavioral effects
resulting from loss of gene function in the mouse knockouts we have generated
using our gene trapping and gene targeting technologies and catalogue those
effects in our comprehensive and relational LexVision database. These analyses
include many of the most sophisticated diagnostic technologies and tests
currently available, many of which might be found in a major medical center.
Each of these technologies has been adapted specifically for the analysis of
mouse physiology. This state-of-the-art technology platform enables us to assess
the consequences of loss of gene function in a living mammal across a wide
variety of parameters relevant to human disease.

We employ the same physiological analysis technology platform that we use
in the discovery of gene function to analyze the in vivo efficacy and safety
profiles of therapeutic candidates in mice. We believe that this approach will
allow us, at an early stage, to identify and optimize therapeutic candidates for
further preclinical and clinical development that demonstrate in vivo efficacy
and to distinguish side effects caused by a specific compound from the
target-related side effects that we defined using the same comprehensive series
of tests.

PRODUCTION AND ANALYSIS INFRASTRUCTURE

Our facilities, which are among the largest and most sophisticated of their
kind in the world, enable us to capitalize on our gene knockout and
physiological analysis technologies by generating knockout mice and analyzing
the physiological function of genes on an expansive scale. We are able to
generate knockout mice for the large number of genes that we believe may be
pharmaceutically important and analyze the physiology and behavior of each of
those knockout mice by utilizing our broad range of analytical technologies. Our
state-of-the-art animal facilities, occupying a total of approximately 100,000
square feet, are designed to allow us to generate and analyze approximately
1,000 knockout mice per year. These facilities, completed in 1999 and 2002,
respectively, were


3
custom designed for the generation and analysis of knockout mice and are
accredited by AAALAC International, or Association for Assessment and
Accreditation of Laboratory Animal Care.

Our facilities also enable us to maintain in-house control over our entire
in vivo validation process, from the generation of embryonic stem cell clones
through the completion of in vivo analysis, in a specific pathogen-free
environment. As part of our Genome5000 program, we have already examined the
physiological functions of more than 3,000 genes and expect to complete our
analysis of an aggregate of 5,000 genes by the end of 2008. We are not aware of
any existing competitive effort approaching either the magnitude or breadth of
our Genome5000 program, and we believe that the investment of significant
resources over a period of several years would be required for any competitor to
duplicate our gene knockout and physiological analysis capabilities. The scope
of our gene knockout technology, combined with the size and sophistication of
our facilities and our evaluative technologies, provides us with what we believe
to be a significant competitive advantage.

MEDICINAL CHEMISTRY TECHNOLOGY

We use solution-phase chemistry to generate diverse libraries of optically
pure compounds that are targeted against the same pharmaceutically relevant gene
families that we address in our Genome5000 program. These libraries are built
using highly robust and scalable organic reactions that allow us to generate
compound collections of great diversity and to specially tailor the compound
collections to address various therapeutic target families. We design these
libraries by analyzing the chemical structures of drugs that have been proven
safe and effective against human disease and using that knowledge in the design
of scaffolds and chemical building blocks for the generation of large numbers of
new drug-like compounds. When we identify a hit against one of our in
vivo-validated targets, we can rapidly reassemble these building blocks to
create hundreds or thousands of variations around the structure of the initial
compound, enabling us to accelerate our medicinal chemistry efforts.

Our medicinal chemistry technology is housed in a state-of-the-art 76,000
square foot facility in Hopewell, New Jersey. Our lead optimization chemistry
groups are organized around specific discovery targets and work closely with
their pharmaceutical biology counterparts in our facilities in The Woodlands,
Texas. The medicinal chemists optimize lead compounds in order to select
clinical candidates with the desired absorption, distribution, metabolism,
excretion and physicochemical characteristics. We have the capability to profile
our compounds using the same battery of in vivo assays that we use to
characterize our drug discovery targets. This provides us with valuable detailed
information relevant to the selection of the highest quality compounds for
clinical development.

RESEARCH AND DEVELOPMENT EXPENSES

In 2005, 2004 and 2003, respectively, we incurred expenses of $93.6
million, $90.6 million and $82.2 million in company-sponsored as well as
collaborative research and development activities, including $0.4 million and
$5.0 million, of stock-based compensation expense in 2004 and 2003,
respectively.

OUR COMMERCIALIZATION STRATEGY

We are working both independently and through strategic collaborations and
alliances with leading pharmaceutical and biotechnology companies, research
institutes and academic institutions to commercialize our technology and turn
our discoveries into drugs. Consistent with this approach, we intend to develop
and commercialize certain of our drug discovery programs internally and retain
exclusive rights to the benefits of such programs and to collaborate with third
parties with respect to the development and commercialization of other drug
discovery programs.

We apply internal resources to discover and develop therapeutics based on
some of our drug target discoveries, allocating our internal resources in a
manner designed to maximize our ability to commercialize opportunities presented
by these programs. Our prioritization and allocation of internal resources among
these programs are based on our expectations regarding their relative likelihood
of success and the relevant medical market, as well as progress realized in our
drug discovery efforts for the program. We revise our prioritization and
resource allocation among programs as necessary in order to capitalize on new
discoveries and opportunities.

Our collaboration and alliance strategy involves drug discovery alliances
to discover and develop therapeutics based on our drug target discoveries,
particularly when the alliance enables us to obtain access to technology and
expertise that we do not possess internally or is complementary to our own.
These strategic collaborations, as well as our licenses with pharmaceutical and
biotechnology companies, research institutes and academic institutions, enable
us to generate near-term cash and revenues in exchange for access to some of our


4
technologies and discoveries for use by these third parties in their own drug
discovery efforts. These collaborations and licenses also offer us the
potential, in many cases, to receive milestone payments and royalties on
products that our collaborators and licensees develop using our technology.

ALLIANCES, COLLABORATIONS AND LICENSES

DRUG DISCOVERY ALLIANCES

We have entered into the following alliances for the discovery and
development of therapeutics based on our in vivo drug target discovery efforts:

Bristol-Myers Squibb Company. We established a drug discovery alliance with
Bristol-Myers Squibb in December 2003 to discover, develop and commercialize
small molecule drugs in the neuroscience field. We initiated the alliance with a
number of neuroscience drug discovery programs at various stages of development
and are continuing to use our gene knockout technology to identify additional
drug targets with promise in the neuroscience field. For those targets that are
selected for the alliance, we and Bristol-Myers Squibb are working together, on
an exclusive basis, to identify, characterize and carry out the preclinical
development of small molecule drugs, and share equally both in the costs and in
the work attributable to those efforts. As drugs resulting from the alliance
enter clinical trials, Bristol-Myers Squibb will have the first option to assume
full responsibility for clinical development and commercialization.

We received an upfront payment under the agreement and are entitled to
receive research funding during the initial three years of the agreement. We may
receive additional cash payments if we exceed specified research productivity
levels. We will also receive clinical and regulatory milestone payments for each
drug target for which Bristol-Myers Squibb develops a drug under the alliance
and royalties on sales of drugs commercialized by Bristol-Myers Squibb. The
target discovery portion of the alliance has a term of three years, subject to
Bristol-Myers Squibb's option to extend the discovery portion of the alliance
for an additional two years in exchange for further research funding payments.

Genentech, Inc. We established a drug discovery alliance with Genentech in
December 2002 to discover novel therapeutic proteins and antibody targets. We
and Genentech expanded the alliance in November 2005 for the advanced research,
development and commercialization of new biotherapeutic drugs. Under the
original alliance agreement, we used our target validation technologies to
discover the functions of secreted proteins and potential antibody targets
identified through Genentech's internal drug discovery research. In the expanded
alliance, we are conducting additional, advanced research on a broad subset of
those proteins and targets. We may develop and commercialize biotherapeutic
drugs for up to six of these targets, with Genentech having exclusive rights to
develop and commercialize biotherapeutic drugs for the other targets. Genentech
retains an option on the potential development and commercialization of the
biotherapeutic drugs that we develop from the alliance under a cost and profit
sharing arrangement, while we have certain conditional rights to co-promote
drugs on a worldwide basis. We retain certain other rights to discoveries made
in the alliance, including non-exclusive rights, along with Genentech, for the
development and commercialization of small molecule drugs addressing the targets
included in the alliance.

We received upfront payments in connection with both the initiation of the
original collaboration and its expansion and are entitled to receive performance
payments for our work in the collaboration as it is completed. We are also
entitled to receive milestone payments and royalties on sales of therapeutic
proteins and antibodies for which Genentech obtains exclusive rights. Genentech
is entitled to receive milestone payments and royalties on sales of therapeutic
proteins and antibodies for which Lexicon obtains exclusive rights. The
agreement, as extended, has an expected collaboration term of six years.

N.V. Organon. We established a drug discovery alliance with Organon in May
2005 to discover, develop and commercialize novel biotherapeutic drugs. In the
collaboration, we are creating and analyzing knockout mice for up to 300 genes
selected by the parties that encode secreted proteins or potential antibody
targets, including two of our preexisting drug discovery programs. We and
Organon will jointly select targets for further research and development and
will equally share costs and responsibility for research, preclinical and
clinical activities. We and Organon will jointly determine the manner in which
collaboration products will be commercialized and will equally benefit from
product revenue. If fewer than five development candidates are designated under
the collaboration, our share of costs and product revenue will be proportionally
reduced. We will receive a milestone payment for each development candidate in
excess of five. Either party may decline to participate in further research or
development efforts with respect to a collaboration product, in which case such
party will receive royalty payments on sales of such collaboration product
rather than sharing in revenue. Organon will have principal responsibility for


5
manufacturing biotherapeutic products resulting from the collaboration for use
in clinical trials and for worldwide sales.

We received an upfront payment under the agreement and are entitled to
receive committed research funding during the first two years of the agreement.
The target discovery portion of the alliance has an expected term of four years.

Takeda Pharmaceutical Company Limited. We established a drug discovery
alliance with Takeda in July 2004 to discover new drugs for the treatment of
high blood pressure. In the collaboration, we are using our gene knockout
technology to identify drug targets that control blood pressure. Takeda will be
responsible for the screening, medicinal chemistry, preclinical and clinical
development and commercialization of drugs directed against targets selected for
the alliance, and will bear all related costs. We received an upfront payment
under the agreement and are entitled to receive research milestone payments for
each target selected for therapeutic development. In addition, we are entitled
to receive clinical development and product launch milestone payments for each
product commercialized from the collaboration. We will also earn royalties on
sales of drugs commercialized by Takeda. The target discovery portion of the
alliance has a term of three years, subject to Takeda's option to extend the
discovery portion of the alliance for an additional two years in exchange for
further research funding payments.

OTHER COMMERCIAL COLLABORATIONS

Taconic Farms, Inc. We established a collaboration with Taconic Farms, Inc.
in November 2005 for the marketing, distribution and licensing of certain lines
of our knockout mice. Taconic is an industry leader in the breeding, housing,
quality control and global marketing and distribution of rodent models for
medical research and drug discovery. Under the terms of the collaboration, we
are initially making available more than 1,000 distinct lines of knockout mice
for use by pharmaceutical and biotechnology companies and other researchers.
Taconic will provide breeding services and licenses for these lines and will
distribute knockout mice to customers. We will receive license fees and
royalties from payments received by Taconic from customers obtaining access to
such knockout mice.

Target Validation Collaborations. We have established target validation
collaboration agreements with a number of leading pharmaceutical and
biotechnology companies. Under these collaboration agreements, we generate and,
in some cases, analyze knockout mice for genes requested by the collaborator. In
addition, we grant non-exclusive licenses to the collaborator for use of the
knockout mice in its internal drug discovery programs and, if applicable,
analysis data that we generate under the agreement. Some of these agreements
also provide for non-exclusive access to our OmniBank database. We receive fees
for knockout mice under these agreements. In some cases, these agreements also
provide for annual minimum commitments and the potential for royalties on
products that our collaborators discover or develop using our technology.

LexVision Collaborations. The collaboration periods have terminated under
each of our LexVision collaborations, pursuant to which our LexVision
collaborators obtained non-exclusive access to our LexVision database of in
vivo-validated drug targets for the discovery of small molecule compounds. We
remain entitled to receive milestone payments and royalties on products those
LexVision collaborators develop using our technology.

E-BIOLOGY COLLABORATION PROGRAM

We provide access to our OmniBank database through the Internet to
subscribing researchers at academic and non-profit research institutions. Our
bioinformatics software allows subscribers to mine our OmniBank database for
genes of interest, and we permit subscribers to acquire OmniBank knockout mice
or embryonic stem cells on a non-exclusive basis in our e-Biology collaboration
program. We receive fees for knockout mice or embryonic stem cells provided to
collaborators in this program and, with participating institutions, rights to
license inventions or to receive royalties on products discovered using our
materials. In all cases we retain rights to use the same OmniBank knockout mice
in our own gene function research and with commercial collaborators. We have
entered into more than 250 agreements under our e-Biology collaboration program
with researchers at leading institutions throughout the world.


6
GOVERNMENT GRANTS AND CONTRACTS

Texas Institute for Genomic Medicine. In July 2005, we received an award
from the Texas Enterprise Fund for the creation of a knockout mouse embryonic
stem cell library containing 350,000 cell lines using our proprietary gene
trapping technology. We are creating the library for the Texas Institute for
Genomic Medicine, or TIGM, a newly formed non-profit institute whose founding
members are Texas A&M University, the Texas A&M University System Health Science
Center and us. TIGM researchers may also access specific cells from our current
OmniBank library of 270,000 mouse embryonic stem cell lines and will have
certain rights to utilize our gene targeting technologies. In addition, we will
equip TIGM with the bioinformatics software required for the management and
analysis of data relating to the library. The Texas Enterprise Fund also made an
award to the Texas A&M University System for the creation of facilities and
infrastructure to house the library.

National Institutes of Health. In October 2005, we entered into a
three-year contract to provide selected knockout mouse lines and related
phenotypic data to the United States National Institutes of Health, or NIH.
Under the contract, NIH may select lines of knockout mice and related phenotypic
data from among lines that we have elected to make available. These materials
are related to genes that we have already knocked out and analyzed. NIH will
make materials acquired from us under the contract available to researchers at
academic and other non-profit research institutions. We retain the sole right to
provide these materials to commercial entities. We are entitled to receive
staged payments from NIH following delivery and acceptance of materials under
the contract.

TECHNOLOGY LICENSES

We have granted non-exclusive, internal research-use sublicenses under
certain of our gene targeting patent rights to a total of 15 leading
pharmaceutical and biotechnology companies. Many of these agreements extend for
the life of the patents. Others have terms of one to three years, in some cases
with provisions for subsequent renewals. We typically receive up-front license
fees and, in some cases, receive additional license fees or milestone payments
on products that the sublicensee discovers or develops using our technology.

PATENTS AND PROPRIETARY RIGHTS

We will be able to protect our proprietary rights from unauthorized use by
third parties only to the extent that those rights are covered by valid and
enforceable patents or are effectively maintained as trade secrets. Accordingly,
patents and other proprietary rights are an essential element of our business.
We seek patent protection for the genes, proteins and drug targets that we
discover. Specifically, we seek patent protection for:

- the sequences of genes that we believe to be novel, including
full-length human genes and partial human and mouse gene sequences,
the proteins they encode and their predicted utility as a drug target
or therapeutic protein;

- the utility of genes and the drug targets or therapeutic proteins they
encode based on our discoveries of their biological functions using
knockout mice;

- drug discovery assays for our in vivo-validated targets;

- chemical compounds and their use in treating human diseases and
conditions; and

- various enabling technologies in the fields of mutagenesis, embryonic
stem cell manipulation and transgenic or knockout mice.

We own or have exclusive rights to nine issued United States patents that
are directed to our gene trapping technology, 84 issued United States patents
that are directed to full-length sequences of potential drug targets identified
in our gene discovery programs, and five issued United States patents that are
directed to specific knockout mice and discoveries of the functions of genes
made using knockout mice. We have licenses under 77 additional United States
patents, and corresponding foreign patents and patent applications, directed to
gene targeting, gene trapping and genetic manipulation of mouse embryonic stem
cells. These include patents to which we hold exclusive rights in certain
fields, including a total of nine United States patents directed to the use of
gene targeting technologies known as positive-negative selection and isogenic
DNA targeting, as well as patents directed to the use of site specific genetic
recombination technology known as Cre/lox technology.

We have filed or have exclusive rights to more than 700 pending patent
applications in the United States Patent and Trademark Office, the European
Patent Office, the national patent offices of other foreign countries or


7
under the Patent Cooperation Treaty, directed to our gene trapping technology,
the DNA sequences of genes, the uses of specific drug targets, drug discovery
assays, and other products and processes. Collectively, these patent
applications are directed to, among other things, approximately 200 full-length
human gene sequences, more than 50,000 partial human gene sequences, and more
than 45,000 knockout mouse clones and corresponding mouse gene sequence tags.
Patents typically have a term of no longer than 20 years from the date of
filing.

As noted above, we hold rights to a number of these patents and patent
applications under license agreements with third parties. In particular, we
license our principal gene targeting technologies from GenPharm International,
Inc. and our Cre/lox technology from DuPont Pharmaceuticals Company, now a
subsidiary of Bristol-Myers Squibb. Many of these licenses are nonexclusive,
although some are exclusive in specified fields. Most of the licenses, including
those licensed from GenPharm and DuPont, have terms that extend for the life of
the licensed patents. In the case of our license from GenPharm, the license
generally is exclusive in specified fields, subject to specific rights held by
third parties, and we are permitted to grant sublicenses.

All of our employees, consultants and advisors are required to execute a
proprietary information agreement upon the commencement of employment or
consultation. In general, the agreement provides that all inventions conceived
by the employee or consultant, and all confidential information developed or
made known to the individual during the term of the agreement, shall be our
exclusive property and shall be kept confidential, with disclosure to third
parties allowed only in specified circumstances. We cannot assure you, however,
that these agreements will provide useful protection of our proprietary
information in the event of unauthorized use or disclosure of such information.

COMPETITION

The biotechnology and pharmaceutical industries are highly competitive and
characterized by rapid technological change. We face significant competition in
each of the aspects of our business from for-profit companies such as Human
Genome Sciences, Inc., Millennium Pharmaceuticals, Inc. and Exelixis, Inc.,
among others, many of which have substantially greater financial, scientific and
human resources than we do. In addition, a large number of universities and
other not-for-profit institutions, many of which are funded by the U.S. and
foreign governments, are also conducting research to discover genes and their
functions.

While we are not aware of any other commercial entity that is developing
large-scale gene trap knockout mouse ES cell libraries, we face competition from
entities using traditional knockout mouse technology and other technologies.
Several companies, including Regeneron Pharmaceuticals, Inc. and DNX (a
subsidiary of Xenogen Corporation), and a large number of academic institutions
create knockout mice for third parties using these more traditional methods, and
a number of companies create knockout mice for use in their own research.

Many of our competitors in drug discovery and development have
substantially greater research and product development capabilities and
financial, scientific, marketing and human resources than we do. As a result,
our competitors may succeed in developing products earlier than we do, obtaining
approvals from the FDA or other regulatory agencies for those products more
rapidly than we do, or developing products that are more effective than those we
propose to develop. Similarly, our collaborators face similar competition from
other competitors who may succeed in developing products more quickly, or
developing products that are more effective, than those developed by our
collaborators. We expect that competition in this field will intensify.

GOVERNMENT REGULATION

REGULATION OF PHARMACEUTICAL PRODUCTS

The development, manufacture and sale of any pharmaceutical or biological
products developed by us or our collaborators will be subject to extensive
regulation by United States and foreign governmental authorities, including
federal, state and local authorities. In the United States, new drugs are
subject to regulation under the Federal Food, Drug and Cosmetic Act and the
regulations promulgated thereunder, or the FDC Act, and biological products are
subject to regulation both under certain provisions of the FDC Act and under the
Public Health Services Act and the regulations promulgated thereunder, or the
PHS Act. The FDA regulates, among other things, the development, preclinical and
clinical testing, manufacture, safety, efficacy, record keeping, reporting,
labeling, storage, approval, advertising, promotion, sale, distribution and
export of drugs and biologics. The process of obtaining FDA approval has
historically been costly and time-consuming.


8
The standard process required by the FDA before a pharmaceutical or
biological product may be marketed in the United States includes:

- preclinical laboratory and animal tests performed under the FDA's
current Good Laboratory Practices regulations;

- submission to the FDA of an Investigational New Drug application, or
IND, which must become effective before human clinical trials may
commence;

- adequate and well-controlled human clinical trials to establish the
safety and efficacy of the drug or biologic in our intended
application;

- for drugs, submission of a New Drug Application, or NDA, and, for
biologics, submission of a Biologic License Application, or BLA, with
the FDA; and

- FDA approval of the NDA or BLA prior to any commercial sale or
shipment of the product.

Among other things, the FDA reviews an NDA to determine whether a product
is safe and effective for its intended use and a BLA to determine whether a
product is safe, pure and potent and the facility in which it is manufactured,
processed, packed, or held meets standards designed to assure the product's
continued safety, purity and potency.

In addition to obtaining FDA approval for each product, each drug or
biologic manufacturing establishment must be inspected and approved by the FDA.
All manufacturing establishments are subject to inspections by the FDA and by
other federal, state and local agencies and must comply with current Good
Manufacturing Practices requirements. Non-compliance with these requirements can
result in, among other things, total or partial suspension of production,
failure of the government to grant approval for marketing and withdrawal,
suspension or revocation of marketing approvals.

Preclinical studies can take several years to complete, and there is no
guarantee that an IND based on those studies will become effective to even
permit clinical testing to begin. Once clinical trials are initiated, they take
years to complete. In addition, the FDA may place a clinical trial on hold or
terminate it if, among other reasons, the agency concludes that clinical
subjects are being exposed to an unacceptable health risk. After completion of
clinical trials of a new drug or biologic product, FDA marketing approval of the
NDA or BLA must be obtained. An NDA or BLA, depending on the submission, must
contain, among other things, information on chemistry, manufacturing controls
and potency and purity, non-clinical pharmacology and toxicology, human
pharmacokinetics and bioavailability and clinical data. The process of obtaining
approval requires substantial time and effort and there is no assurance that the
FDA will accept the NDA or BLA for filing and, even if filed, that approval will
be granted. The FDA's approval of an NDA or BLA can take years and can be
delayed if questions arise. Limited indications for use or other conditions
could also be placed on any approvals that could restrict the commercial
applications of products.

Once the FDA approves a product, a manufacturer must provide certain
updated safety and efficacy information. Product changes as well as certain
changes in a manufacturing process or facility would necessitate additional FDA
review and approval. Other post-approval changes may also necessitate further
FDA review and approval. Additionally, a manufacturer must meet other
requirements including those related to adverse event reporting and record
keeping.

Violations of the FDC Act, the PHS Act or regulatory requirements may
result in agency enforcement action, including voluntary or mandatory recall,
license suspension or revocation, product seizure, fines, injunctions and civil
or criminal penalties.

In addition to regulatory approvals that must be obtained in the United
States, a drug or biological product is also subject to regulatory approval in
other countries in which it is marketed. The conduct of clinical trials of drugs
and biological products in countries other than the United States is likewise
subject to regulatory oversight in such countries. The requirements governing
the conduct of clinical trials, product licensing, pricing, and reimbursement
vary widely from country to country. No action can be taken to market any drug
or biological product in a country until the regulatory authorities in that
country have approved an appropriate application. FDA approval does not assure
approval by other regulatory authorities. The current approval process varies
from country


9
to country, and the time spent in gaining approval varies from that required for
FDA approval. In some countries, the sale price of a drug or biological product
must also be approved. The pricing review period often begins after marketing
approval is granted. Even if a foreign regulatory authority approves a drug or
biological product, it may not approve satisfactory prices for the product.

OTHER REGULATIONS

In addition to the foregoing, our business is and will be subject to
regulation under various state and federal environmental laws, including the
Occupational Safety and Health Act, the Resource Conservation and Recovery Act
and the Toxic Substances Control Act. These and other laws govern our use,
handling and disposal of various biological, chemical and radioactive substances
used in and wastes generated by our operations. We believe that we are in
material compliance with applicable environmental laws and that our continued
compliance with these laws will not have a material adverse effect on our
business. We cannot predict, however, whether new regulatory restrictions on the
production, handling and marketing of biotechnology products will be imposed by
state or federal regulators and agencies or whether existing laws and
regulations will adversely affect us in the future.

EMPLOYEES AND CONSULTANTS

We believe that our success will be based on, among other things, achieving
and retaining scientific and technological superiority and identifying and
retaining capable management. We have assembled a highly qualified team of
scientists as well as executives with extensive experience in the biotechnology
industry.

As of February 28, 2006, we employed 755 persons, of whom 156 hold M.D.,
Ph.D. or D.V.M. degrees and another 109 hold other advanced degrees. We believe
that our relationship with our employees is good.

RISK FACTORS

The following risks and uncertainties are important factors that could
cause actual results or events to differ materially from those indicated by
forward-looking statements. The factors described below are not the only ones we
face and additional risks and uncertainties not presently known to us or that we
currently deem immaterial also may impair our business operations.

RISKS RELATED TO OUR NEED FOR ADDITIONAL FINANCING AND OUR FINANCIAL RESULTS

We will need additional capital in the future and, if it is not available on
reasonable terms, we will be forced to significantly curtail or cease operations
or obtain funds by entering into financing agreements on unattractive terms.

As of December 31, 2005, we had cash, cash equivalents and short-term
investments (net of restricted cash and investments) of $99.3 million. We
anticipate that our existing capital resources and the cash and revenues we
expect to derive from drug discovery alliances, collaborations for the
development and, in some cases, analysis of the physiological effects of genes
altered in knockout mice, government grants and contracts and technology
licenses will enable us to fund our currently planned operations for
approximately the next two years. Our currently planned operations for that time
period consist of the continuation of our efforts to discover the physiological
functions of 5,000 human genes that we consider to be pharmaceutically
important, the expansion of our medicinal chemistry, biotherapeutics and
preclinical research operations and the initiation of clinical trials. However,
we caution you that we may generate less cash and revenues or incur expenses
more rapidly than we currently anticipate.

Although difficult to accurately predict, the amount of our future capital
requirements will be substantial and will depend on many factors, including:

- our ability to obtain additional funds from alliances, collaborations,
government grants and contracts and technology licenses;

- the amount and timing of payments under such agreements;

- the level and timing of our research and development expenditures;

- future results from clinical trials that we initiate;


10
-    the cost and timing of regulatory approvals of products that we
successfully develop; and

- market acceptance of products that we successfully develop and
commercially launch.

Our capital requirements will increase substantially to the extent we
advance potential therapeutics into clinical development. Our capital
requirements will also be affected by any expenditures we make in connection
with license agreements and acquisitions of and investments in complementary
products and technologies. For all of these reasons, our future capital
requirements cannot easily be quantified.

If our capital resources are insufficient to meet future capital
requirements, we will have to raise additional funds to continue our currently
planned operations. If we raise additional capital by issuing equity securities,
our then-existing stockholders will experience dilution and the terms of any new
equity securities may have preferences over our common stock. We cannot be
certain that additional financing, whether debt or equity, will be available in
amounts or on terms acceptable to us, if at all. We may be unable to raise
sufficient additional capital on reasonable terms; if so, we will be forced to
significantly curtail or cease operations or obtain funds by entering into
financing agreements on unattractive terms.

We have a history of net losses, and we expect to continue to incur net losses
and may not achieve or maintain profitability.

We have incurred net losses since our inception, including net losses of
$36.3 million for the year ended December 31, 2005, $47.2 million for the year
ended December 31, 2004 and $64.2 million for the year ended December 31, 2003.
As of December 31, 2005, we had an accumulated deficit of $297.4 million. We are
unsure when we will become profitable, if ever. The size of our net losses will
depend, in part, on the rate of growth, if any, in our revenues and on the level
of our expenses.

We derive substantially all of our revenues from drug discovery alliances,
collaborations for the development and, in some cases, analysis of the
physiological effects of genes altered in knockout mice, government grants and
contracts and technology licenses, and will continue to do so for the
foreseeable future. Our future revenues from alliances, collaborations and
government grants and contracts are uncertain because our existing agreements
have fixed terms or relate to specific projects of limited duration. Our future
revenues from technology licenses are uncertain because they depend, in part, on
securing new agreements. Our ability to secure future revenue-generating
agreements will depend upon our ability to address the needs of our potential
future collaborators, granting agencies and licensees, and to negotiate
agreements that we believe are in our long-term best interests. We may determine
that our interests are better served by retaining rights to our discoveries and
advancing our therapeutic programs to a later stage, which could limit our
near-term revenues. Given the early-stage nature of our operations, we do not
currently derive any revenues from sales of pharmaceutical products.

A large portion of our expenses is fixed, including expenses related to
facilities, equipment and personnel. In addition, we expect to spend significant
amounts to enhance our core technologies and fund our research and development
activities, including the advancement of potential therapeutics into clinical
development. As a result, we expect that our operating expenses will continue to
increase significantly in the near term and, consequently, we will need to
generate significant additional revenues to achieve profitability. Even if we do
achieve profitability, we may not be able to sustain or increase profitability
on a quarterly or annual basis.

Our operating results have been and likely will continue to fluctuate, and we
believe that period-to-period comparisons of our operating results are not a
good indication of our future performance.

Our operating results and, in particular, our ability to generate
additional revenues are dependent on many factors, including:

- our ability to establish new collaborations and alliances, government
grants and contracts, and technology licenses, and the timing of such
arrangements;

- the expiration or other termination of collaborations and alliances,
which may not be renewed or replaced;

- the success rate of our discovery efforts leading to opportunities for
new collaborations, alliances and licenses, as well as milestone
payments and royalties;


11
-    the timing and willingness of our collaborators to commercialize
pharmaceutical products that would result in milestone payments and
royalties; and

- general and industry-specific economic conditions, which may affect
our and our collaborators' research and development expenditures.

Because of these and other factors, including the risks and uncertainties
described in this section, our operating results have fluctuated in the past and
are likely to do so in the future. Due to the likelihood of fluctuations in our
revenues and expenses, we believe that period-to-period comparisons of our
operating results are not a good indication of our future performance.

RISKS RELATED TO OUR BUSINESS

We are an early-stage company, and we may not successfully develop or
commercialize any therapeutics that we have identified.

Our business strategy of using our technology platform and, specifically,
the discovery of the functions of genes using knockout mice to select promising
drug targets and developing and commercializing drugs based on our discoveries,
in significant part through collaborations and alliances, is unproven. Our
success will depend upon our ability to successfully develop potential
therapeutics for drug targets we consider to have pharmaceutical value, whether
on our own or through collaborations, and to select an appropriate
commercialization strategy for each potential therapeutic we choose to pursue.

Biotechnology and pharmaceutical companies have successfully developed and
commercialized only a limited number of genomics-derived pharmaceutical products
to date. We have not proven our ability to develop or commercialize therapeutics
or drug targets that we identify, nor have we advanced any drug candidates to
clinical trials. We do not know that any pharmaceutical products based on our
drug target discoveries can be successfully commercialized. In addition, we may
experience unforeseen technical complications in the processes we use to
discover and develop potential therapeutics. These complications could
materially delay or limit the use of our resources, substantially increase the
anticipated cost of generating them or prevent us from implementing our
processes at appropriate quality and throughput levels.

Clinical testing of our future drug candidates in humans is an inherently risky
and time-consuming process that may fail to demonstrate safety and efficacy,
which could result in the delay, limitation or prevention of regulatory
approval.

In order to obtain regulatory approvals for the commercial sale of any
products that we may develop, we will be required to complete extensive clinical
trials in humans to demonstrate the safety and efficacy of our drug candidates.
We or our collaborators may not be able to obtain authority from the United
States Food and Drug Administration, or FDA, or other equivalent foreign
regulatory agencies to initiate or complete any clinical trials. In addition, we
have limited internal resources for making regulatory filings and dealing with
regulatory authorities.

Clinical trials are inherently risky and the results from preclinical
testing of a drug candidate that is under development may not be predictive of
results that will be obtained in human clinical trials. In addition, the results
of early human clinical trials may not be predictive of results that will be
obtained in larger scale, advanced stage clinical trials. A number of companies
in the pharmaceutical industry have suffered significant setbacks in advanced
clinical trials, even after achieving positive results in earlier trials.
Negative or inconclusive results from a preclinical study or a clinical trial
could cause us, one of our collaborators or the FDA to terminate a preclinical
study or clinical trial or require that we repeat it. Furthermore, we, one of
our collaborators or a regulatory agency with jurisdiction over the trials may
suspend clinical trials at any time if the subjects or patients participating in
such trials are being exposed to unacceptable health risks or for other reasons.

Any preclinical or clinical test may fail to produce results satisfactory
to the FDA or foreign regulatory authorities. Preclinical and clinical data can
be interpreted in different ways, which could delay, limit or prevent regulatory
approval. The FDA or institutional review boards at the medical institutions and
healthcare facilities where we sponsor clinical trials may suspend any trial
indefinitely if they find deficiencies in the conduct of these trials. Clinical
trials must be conducted in accordance with the FDA's current Good Clinical
Practices. The FDA and these institutional review boards have authority to
oversee our clinical trials, and the FDA may require large numbers of test
subjects. In addition, we must manufacture, or contract for the manufacture of,
the product candidates that we use in our clinical trials under the FDA's
current Good Manufacturing Practices.


12
The rate of completion of clinical trials is dependent, in part, upon the
rate of enrollment of patients. Patient accrual is a function of many factors,
including the size of the patient population, the proximity of patients to
clinical sites, the eligibility criteria for the study, the nature of the study,
the existence of competitive clinical trials and the availability of alternative
treatments. Delays in planned patient enrollment may result in increased costs
and prolonged clinical development, which in turn could allow our competitors to
bring products to market before we do and impair our ability to commercialize
our products or potential products.

We or our collaborators may not be able to successfully complete any
clinical trial of a potential product within any specified time period. In some
cases, we or our collaborators may not be able to complete the trial at all.
Moreover, clinical trials may not show our potential products to be both safe
and effective. Thus, the FDA and other regulatory authorities may not approve
any products that we develop for any indication or may limit the approved
indications or impose other conditions.

We are dependent upon our collaborations with major pharmaceutical companies. If
we are unable to achieve milestones under those collaborations or if our
collaborators' efforts fail to yield pharmaceutical products on a timely basis,
our business will suffer.

We have derived a substantial majority of our revenues to date from
collaborative drug discovery alliances with a limited number of major
pharmaceutical companies. Revenues from our drug discovery alliances depend upon
continuation of the collaborations, the achievement of milestones and payment of
royalties we earn from any future products developed under the collaborations.
If our relationship terminates with any of our collaborators, our reputation in
the business and scientific community may suffer and revenues will be negatively
impacted to the extent such losses are not offset by additional collaboration
agreements. If we are unable to achieve milestones or our collaborators are
unable to successfully develop products from which royalties are payable, we
will not earn the revenues contemplated by those drug discovery alliances. In
addition, some of our alliances are exclusive and preclude us from entering into
additional collaborative arrangements with other parties in the field of
exclusivity.

We have limited or no control over the resources that any collaborator may
devote to the development and commercialization of products under our alliances.
Any of our present or future collaborators may not perform their obligations as
expected. These collaborators may breach or terminate their agreements with us
or otherwise fail to conduct product discovery, development or commercialization
activities successfully or in a timely manner. Further, our collaborators may
elect not to develop pharmaceutical products arising out of our collaborative
arrangements or may not devote sufficient resources to the development,
approval, manufacture, marketing or sale of these products. If any of these
events occurs, we may not be able to develop or commercialize potential
pharmaceutical products.

Conflicts with our collaborators could jeopardize the success of our
collaborative agreements and harm our product development efforts.

We may pursue opportunities in specific disease and therapeutic modality
fields that could result in conflicts with our collaborators, if any of our
collaborators takes the position that our internal activities overlap with those
activities that are exclusive to our collaboration. Moreover, disagreements
could arise with our collaborators over rights to our intellectual property or
our rights to share in any of the future revenues of compounds or therapeutic
approaches developed by our collaborators. Any conflict with or among our
collaborators could result in the termination of our collaborative agreements,
delay collaborative research or development activities, impair our ability to
renew or obtain future collaborative agreements or lead to costly and time
consuming litigation. Conflicts with our collaborators could also have a
negative impact on our relationship with existing collaborators, materially
impairing our business and revenues. Some of our collaborators are also
potential competitors or may become competitors in the future. Our collaborators
could develop competing products, preclude us from entering into collaborations
with their competitors or terminate their agreements with us prematurely. Any of
these events could harm our product development efforts.

If we are unable to internally establish drug development and commercialization
capabilities or arrange for the provision of such functions by third parties,
our ability to develop and commercialize pharmaceutical products would be
significantly impaired.

Our ability to develop and commercialize pharmaceutical products on our own
will depend on our ability to internally develop preclinical, clinical,
regulatory and sales and marketing capabilities, or enter into arrangements with
third parties to provide these functions. It will be expensive and will require
significant time for us to develop


13
these capabilities internally. We may not be successful in developing these
capabilities or entering into agreements with third parties on favorable terms,
or at all. Further, our reliance upon third parties for these capabilities could
reduce our control over such activities and could make us dependent upon these
parties. If these third parties do not successfully carry out their contractual
duties or regulatory obligations or meet expected deadlines, our drug
development activities may be delayed, suspended or terminated. Such a failure
by these third parties, or our inability to develop or contract for these
capabilities, would significantly impair our ability to develop and
commercialize pharmaceutical products.

We lack the capability to manufacture materials for preclinical studies,
clinical trials or commercial sales and will rely on third parties to
manufacture our potential products, which may harm or delay our product
development and commercialization efforts.

We currently do not have the manufacturing capabilities or experience
necessary to produce materials for preclinical studies, clinical trials or
commercial sales and intend to rely on collaborators and third-party contractors
to produce such materials. We will rely on selected manufacturers to deliver
materials on a timely basis and to comply with applicable regulatory
requirements, including the current Good Manufacturing Practices of the FDA,
which relate to manufacturing and quality control activities. These
manufacturers may not be able to produce material on a timely basis or
manufacture material at the quality level or in the quantity required to meet
our development timelines and applicable regulatory requirements. In addition,
there are a limited number of manufacturers that operate under the FDA's current
Good Manufacturing Practices and that are capable of producing such materials,
and we may experience difficulty finding manufacturers with adequate capacity
for our needs. If we are unable to contract for the production of sufficient
quantity and quality of materials on acceptable terms, our product development
and commercialization efforts may be delayed. Moreover, noncompliance with the
FDA's current Good Manufacturing Practices can result in, among other things,
fines, injunctions, civil and criminal penalties, product recalls or seizures,
suspension of production, failure to obtain marketing approval and withdrawal,
suspension or revocation of marketing approvals.

We face substantial competition in our drug discovery and product development
efforts.

We face significant competition in our drug discovery and product
development efforts from other biotechnology and pharmaceutical companies, as
well as from universities and other not-for-profit institutions. In particular,
certain competing companies such as Human Genome Sciences, Inc., Millennium
Pharmaceuticals, Inc. and Exelixis, Inc. utilize a genetics-based approach to
target discovery and validation that is similar to our own. Many of our
competitors have substantially greater financial, scientific and human resources
than we do. As a result, our competitors may succeed in developing products
earlier than we do, obtaining regulatory approvals faster than we do and
developing products that are more effective or safer than any that we may
develop.

We may engage in future acquisitions, which may be expensive and time consuming
and from which we may not realize anticipated benefits.

We may acquire additional businesses, technologies and products if we
determine that these businesses, technologies and products complement our
existing technology or otherwise serve our strategic goals. If we do undertake
any transactions of this sort, the process of integrating an acquired business,
technology or product may result in operating difficulties and expenditures and
may not be achieved in a timely and non-disruptive manner, if at all, and may
absorb significant management attention that would otherwise be available for
ongoing development of our business. If we fail to integrate acquired
businesses, technologies or products effectively or if key employees of an
acquired business leave, the anticipated benefits of the acquisition would be
jeopardized. Moreover, we may never realize the anticipated benefits of any
acquisition, such as increased revenues and earnings or enhanced business
synergies. Future acquisitions could result in potentially dilutive issuances of
our equity securities, the incurrence of debt and contingent liabilities and
amortization expenses related to intangible assets, which could materially
impair our results of operations and financial condition.

If we lose our key personnel or are unable to attract and retain additional
personnel, we may be unable to successfully develop and commercialize our own
products.

We are highly dependent on the principal members of our management and
scientific staff. We do not carry key man insurance on any key personnel and the
loss of any of these personnel could negatively impact our business, financial
condition or results of operations and could inhibit our product development and


14
commercialization efforts. Although we have entered into employment agreements
with some of our key personnel, these employment agreements are all at will. In
addition, not all key personnel have employment agreements.

Recruiting and retaining qualified scientific personnel to perform future
research and development work will be critical to our success. Competition for
experienced scientists is intense. Failure to recruit and retain scientific
personnel on acceptable terms could prevent us from achieving our business
objectives.

Any contamination among our knockout mouse population could negatively affect
the reliability of our scientific research or cause us to incur significant
remedial costs.

Our generation and analysis of knockout mice are conducted in a specific
pathogen-free environment. Any contamination of our knockout mouse population
could distort or compromise the quality of our research and negatively impact
the reliability of our scientific discoveries. Although we have expended
substantial resources in order to secure our facilities from such risk, in the
event such a contamination were to occur, our drug discovery efforts could be
significantly harmed or delayed and our reputation within the scientific
community could be eroded. In addition, we may incur significant remedial costs
relating to the elimination of any pathogens present in our facilities.

Because all of our target validation operations are located at a single
facility, the occurrence of a disaster could significantly disrupt our business.

Our OmniBank mouse clone library and its backup are stored in liquid
nitrogen freezers located at our facility in The Woodlands, Texas, and our
knockout mouse research operations are carried out entirely at the same
facility. While we have developed redundant and emergency backup systems to
protect these resources and the facilities in which they are stored, they may be
insufficient in the event of a severe fire, flood, hurricane, tornado,
mechanical failure or similar disaster. If such a disaster significantly damages
or destroys the facility in which these resources are maintained, our business
could be disrupted until we could regenerate the affected resources and, as a
result, our stock price could decline. Our business interruption insurance may
not be sufficient to compensate us in the event of a major interruption due to
such a disaster.

We use hazardous chemicals and radioactive and biological materials in our
business; any disputes relating to improper handling, storage or disposal of
these materials could be time consuming and costly.

Our research and development processes involve the use of hazardous
materials, including chemicals and radioactive and biological materials. Our
operations also produce hazardous waste products. We cannot eliminate the risk
of accidental contamination or discharge or any resultant injury from these
materials. Federal, state and local laws and regulations govern the use,
manufacture, storage, handling and disposal of these materials. We could be
subject to civil damages in the event of an improper or unauthorized release of,
or exposure of individuals to, these hazardous materials. In addition, claimants
may sue us for injury or contamination that results from our use or the use by
third parties of these materials, and our liability may exceed our total assets.
Compliance with environmental laws and regulations may be expensive, and current
or future environmental regulations may impair our research, development or
production efforts. We do not currently maintain insurance coverage that would
cover these types of environmental liabilities.

RISKS RELATED TO OUR INDUSTRY

Our ability to patent our inventions is uncertain because patent laws and their
interpretation are highly uncertain and subject to change.

The patent positions of pharmaceutical and biotechnology companies
generally are highly uncertain and involve complex legal and factual questions
that will determine who has the right to develop or use a particular technology
or product. No clear policy has emerged regarding the scope of protection
provided in gene, drug target and biopharmaceutical patents. In addition,
certain uses of technologies and products covered by some of these patents may
be subject to statutory exemptions from infringement under applicable law. The
biopharmaceutical patent situation outside the United States is similarly
uncertain. Changes in, or different interpretations of, patent laws in the
United States or other countries might allow others to use our inventions or to
develop and commercialize any technologies or products that we may develop
without any compensation to us. We anticipate that these uncertainties will
continue for a significant period of time.


15
If we are unable to adequately protect our intellectual property, third parties
may be able to use our technology, which could negatively impact our ability to
compete in the market.

Our success will depend, in part, upon our ability to obtain patents and
maintain adequate protection of the intellectual property related to our
technologies and future products. We will be able to protect our intellectual
property rights from unauthorized use by third parties only to the extent that
our technologies are covered by valid and enforceable patents or are effectively
maintained as trade secrets.

Pending patent applications do not provide protection against competitors
because they are not enforceable until they issue as patents. Further, the
disclosures contained in our current and future patent applications may not be
sufficient to meet statutory requirements for patentability. Once issued,
patents still may not provide commercially meaningful protection. If anyone
infringes upon our or our collaborators' patent rights, enforcing these rights
may be difficult, costly and time-consuming and, as a result, it may not be
cost-effective or otherwise expedient to pursue litigation to enforce those
patent rights. Others may be able to design around these patents or develop
unique products providing effects similar to any products that we may develop.
Other companies or institutions may challenge our or our collaborators' patents
or independently develop similar products that could result in an interference
proceeding in the United States Patent and Trademark Office or a legal action.

Patent applications can take many years to issue and there may be currently
pending patent applications of our competitors that later result in issued
patents covering our discoveries. If any such patents are issued to other
entities, we will be unable to obtain patent protection for the same or similar
discoveries that we make. Moreover, we may be blocked from using or developing
some of our existing or proposed technologies and products, or may be required
to obtain a license that may not be available on reasonable terms, if at all.
Further, others may discover uses for our technologies or therapeutic products
other than those covered in our issued or pending patents, and these other uses
may be separately patentable. Even if we have a patent claim on a particular
technology or therapeutic product, the holder of a patent covering the use of
that technology or therapeutic product could exclude us from selling a product
that is based on the same use of that product.

Additionally, significant aspects of our intellectual property are not
protected by patents. As a result, we seek to protect the proprietary nature of
this intellectual property as trade secrets through proprietary information
agreements and other measures. While we have entered into proprietary
information agreements with all of our employees, consultants, advisers and
collaborators, we may not be able to prevent the disclosure of our trade
secrets. In addition, other companies or institutions may independently develop
substantially equivalent information and techniques.

We may be involved in patent litigation and other disputes regarding
intellectual property rights and may require licenses from third parties for our
discovery and development and planned commercialization activities. We may not
prevail in any such litigation or other dispute or be able to obtain required
licenses.

Our discovery and development efforts as well as our potential products and
those of our collaborators may give rise to claims that they infringe the
patents of others. This risk will increase as the biotechnology industry expands
and as other companies and institutions obtain more patents covering the
sequences, functions and uses of genes and the drug targets they encode. We are
aware that other companies and institutions have conducted research on many of
the same targets that we have identified and have filed patent applications
potentially covering many of the genes and encoded drug targets that are the
focus of our drug discovery programs. In some cases, patents have issued from
these applications. In addition, many companies and institutions have
well-established patent portfolios directed to common techniques, methods and
means of developing, producing and manufacturing pharmaceutical products. Other
companies or institutions could bring legal actions against us or our
collaborators for damages or to stop us or our collaborators from engaging in
certain discovery or development activities or from manufacturing and marketing
any resulting therapeutic products. If any of these actions are successful, in
addition to our potential liability for damages, these entities would likely
require us or our collaborators to obtain a license in order to continue
engaging in the infringing activities or to manufacture or market the resulting
therapeutic products or may force us to terminate such activities or
manufacturing and marketing efforts.

We may need to pursue litigation against others to enforce our patents and
intellectual property rights and may be the subject of litigation brought by
third parties to enforce their patent and intellectual property rights. In
addition, we may become involved in litigation based on intellectual property
indemnification undertakings that we have given to certain of our collaborators.
Patent litigation is expensive and requires substantial amounts of management
attention. The eventual outcome of any such litigation is uncertain and involves
substantial risks.


16
We believe that there will continue to be significant litigation in our
industry regarding patent and other intellectual property rights. We have
expended and many of our competitors have expended and are continuing to expend
significant amounts of time, money and management resources on intellectual
property litigation. If we become involved in future intellectual property
litigation, it could consume a substantial portion of our resources and could
negatively affect our results of operations.

We use intellectual property that we license from third parties. If we do not
comply with these licenses, we could lose our rights under them.

We rely, in part, on licenses to use certain technologies that are
important to our business, such as certain gene targeting technology licensed
from GenPharm International, Inc. and conditional knockout technology licensed
from DuPont Pharmaceuticals Company, now a subsidiary of Bristol-Myers Squibb
Company. We do not own the patents that underlie these licenses. Most of these
licenses, however, including those licensed from GenPharm and DuPont, have terms
that extend for the life of the licensed patents. Our rights to use these
technologies and practice the inventions claimed in the licensed patents are
subject to our abiding by the terms of those licenses and the licensors not
terminating them. We are currently in compliance with all requirements of these
licenses. In many cases, we do not control the filing, prosecution or
maintenance of the patent rights to which we hold licenses and rely upon our
licensors to prosecute infringement of those rights. The scope of our rights
under our licenses may be subject to dispute by our licensors or third parties.

We have not sought patent protection outside of the United States for some of
our inventions, and some of our licensed patents only provide coverage in the
United States. As a result, our international competitors could be granted
foreign patent protection with respect to our discoveries.

We have decided not to pursue patent protection with respect to some of our
inventions outside the United States, both because we do not believe it is
cost-effective and because of confidentiality concerns. Accordingly, our
international competitors could develop, and receive foreign patent protection
for, genes or gene sequences, uses of those genes or gene sequences, gene
products and drug targets, assays for identifying potential therapeutic
products, potential therapeutic products and methods of treatment for which we
are seeking United States patent protection. In addition, most of our gene
trapping patents and our licensed gene targeting patents cover only the United
States and do not apply to discovery activities conducted outside of the United
States or, in some circumstances, to importing into the United States products
developed using this technology.

Our industry is subject to extensive and uncertain government regulatory
requirements, which could significantly hinder our ability, or the ability of
our collaborators, to obtain, in a timely manner or at all, regulatory approval
of potential therapeutic products, or to commercialize such products.

Our drug candidates, as well as the activities associated with their
research, development and commercialization, are subject to extensive regulation
by the FDA or other equivalent foreign regulatory agencies. Our failure to
obtain regulatory approval for a drug candidate would prevent us from
commercializing that drug candidate. The regulatory approval process is
expensive, time-consuming and can vary substantially depending on the modality,
complexity and novelty of the drug candidate. The regulatory process includes
extensive preclinical studies and human clinical trials, which can take many
years and may require substantial expenditures. Such preclinical studies or
clinical trials may fail to produce results satisfactory to the FDA or other
equivalent foreign regulatory agencies. Even if we obtain regulatory approval,
the FDA or other equivalent foreign regulatory agency may impose restrictions as
to the approved use and labeling of our product or the types of patients to
which we can market and sell our product. We have limited internal resources
with respect to the regulatory process and have only limited experience in the
preparation and filing of the applications necessary to obtain regulatory
approval.

If our potential products receive regulatory approval, we or our collaborators
will remain subject to extensive and rigorous ongoing regulation.

If we or our collaborators obtain initial regulatory approvals from the FDA
or foreign regulatory authorities for any products that we may develop, we or
our collaborators will be subject to extensive and rigorous ongoing domestic and
foreign government regulation of, among other things, the research, development,
testing, manufacture, labeling, promotion, advertising, distribution and
marketing of our products and product candidates. The failure to comply with
these requirements or the identification of safety problems during commercial
marketing could lead to the need for product marketing restrictions, product
withdrawal or recall or other voluntary or


17
regulatory action, which could delay further marketing until the product is
brought into compliance. The failure to comply with these requirements may also
subject us or our collaborators to stringent penalties.

Moreover, several of our product development areas involve relatively new
technology and have not been the subject of extensive product testing in humans.
The regulatory requirements governing these products and related clinical
procedures remain uncertain and the products themselves may be subject to
substantial review by foreign governmental regulatory authorities that could
prevent or delay approval in those countries. Regulatory requirements ultimately
imposed on any products that we may develop could limit our ability to test,
manufacture and, ultimately, commercialize such products.

The uncertainty of pharmaceutical pricing and reimbursement may decrease the
commercial potential of any products that we or our collaborators may develop
and affect our ability to raise capital.

Our ability and the ability of our collaborators to successfully
commercialize pharmaceutical products will depend, in part, on the extent to
which reimbursement for the cost of such products and related treatment will be
available from government health administration authorities, private health
coverage insurers and other organizations. The pricing, availability of
distribution channels and reimbursement status of newly approved pharmaceutical
products is highly uncertain. As a result, adequate third-party coverage may not
be available for us to maintain price levels sufficient for realization of an
appropriate return on our investment in product discovery and development.

In certain foreign markets, pricing or profitability of healthcare products
is subject to government control. In the United States, there have been, and we
expect that there will continue to be, a number of federal and state proposals
to implement similar governmental control. In addition, an increasing emphasis
on managed care in the United States has increased and will continue to increase
the pressure on pharmaceutical pricing. While we cannot predict the adoption of
any such legislative or regulatory proposals or the effect such proposals or
managed care efforts may have on our business, the announcement of such
proposals or efforts could harm our ability to raise capital, and the adoption
of such proposals or efforts could harm our results of operations. Further, to
the extent that such proposals or efforts harm other pharmaceutical companies
that are our prospective collaborators, our ability to establish corporate
collaborations would be impaired. In addition, third-party payers are
increasingly challenging the prices charged for medical products and services.
We do not know whether consumers, third-party payers and others will consider
any products that we or our collaborators develop to be cost-effective or that
reimbursement to the consumer will be available or will be sufficient to allow
us or our collaborators to sell such products on a profitable basis.

We may be sued for product liability.

We or our collaborators may be held liable if any product that we or our
collaborators develop, or any product that is made with the use or incorporation
of any of our technologies, causes injury or is found otherwise unsuitable
during product testing, manufacturing, marketing or sale. Although we currently
have and intend to maintain product liability insurance, this insurance may
become prohibitively expensive or may not fully cover our potential liabilities.
Our inability to obtain sufficient insurance coverage at an acceptable cost or
otherwise to protect against potential product liability claims could prevent or
inhibit the commercialization of products developed by us or our collaborators.
If we are sued for any injury caused by our or our collaborators' products, our
liability could exceed our total assets.

Public perception of ethical and social issues may limit or discourage the use
of our technologies, which could reduce our revenues.

Our success will depend, in part, upon our ability to develop products
discovered through our knockout mouse technologies. Governmental authorities
could, for ethical, social or other purposes, limit the use of genetic processes
or prohibit the practice of our knockout mouse technologies. Claims that
genetically engineered products are unsafe for consumption or pose a danger to
the environment may influence public perceptions. The subject of genetically
modified organisms, like knockout mice, has received negative publicity and
aroused public debate in some countries. Ethical and other concerns about our
technologies, particularly the use of genes from nature for commercial purposes
and the products resulting from this use, could reduce the likelihood of
maintaining market acceptance of our technologies.


18
ITEM 2. PROPERTIES

We currently own approximately 300,000 square feet of space for our
corporate offices and laboratories in buildings located in The Woodlands, Texas,
a suburb of Houston, Texas, and lease approximately 76,000 square feet of space
for offices and laboratories near Princeton, New Jersey.

Our facilities in The Woodlands, Texas include two state-of-the art animal
facilities totaling approximately 100,000 square feet. These facilities,
completed in 1999 and 2002, respectively, were custom designed for the
generation and analysis of knockout mice and are accredited by AAALAC
International (Association for Assessment and Accreditation of Laboratory Animal
Care). These facilities enable us to maintain in-house control over our entire
in vivo validation process, from the generation of embryonic stem cell clones
through the completion of in vivo analysis, in a specific pathogen free
environment. We believe these facilities, which are among the largest and most
sophisticated of their kind in the world, provide us with significant strategic
and operational advantages relative to our competitors. Because of the size and
sophistication of our facilities, it would require the investment of significant
resources over an extended period of time for any competitor to develop
facilities with the scale, efficiency and productivity with respect to the
analysis of the functionality of genes that our facilities provide.

In April 2004, we purchased our facilities in The Woodlands, Texas from the
lessor under our previous synthetic lease agreement. In connection with such
purchase, we repaid the $54.8 million funded under the synthetic lease with
proceeds from a $34.0 million third-party mortgage financing and $20.8 million
in cash. The mortgage loan has a ten-year term with a 20-year amortization and
bears interest at a fixed rate of 8.23%. As a result of the refinancing, all
restrictions on the cash and investments that had secured the obligations under
the synthetic lease were eliminated.

In May 2002, our subsidiary Lexicon Pharmaceuticals (New Jersey), Inc.
entered into a lease for a 76,000 square-foot facility in Hopewell, New Jersey.
The term of the lease extends until June 30, 2013. The lease provides for an
escalating yearly base rent payment of $1.3 million in the first year, $2.1
million in years two and three, $2.2 million in years four to six, $2.3 million
in years seven to nine and $2.4 million in years ten and eleven. We are the
guarantor of the obligations of our subsidiary under the lease.

We believe that our facilities are well-maintained, in good operating
condition and acceptable for our current operations.

ITEM 3. LEGAL PROCEEDINGS

We are not presently a party to any material legal proceedings.

ITEM 4. SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS

No matters were submitted during the fourth quarter of the year ended
December 31, 2005.


19
PART II

ITEM 5. MARKET FOR REGISTRANT'S COMMON EQUITY AND RELATED STOCKHOLDER MATTERS

Our common stock is quoted on The Nasdaq National Market under the symbol
"LEXG." The following table sets forth, for the periods indicated, the high and
low sales prices for our common stock as reported on The Nasdaq National Market.

<TABLE>
<CAPTION>
HIGH LOW
----- -----
<S> <C> <C>
2004
First Quarter.... $8.19 $5.68
Second Quarter... $8.24 $6.00
Third Quarter.... $7.90 $5.03
Fourth Quarter... $7.95 $6.02

2005
First Quarter.... $8.00 $4.90
Second Quarter... $5.20 $4.15
Third Quarter.... $6.50 $3.82
Fourth Quarter... $4.47 $3.19
</TABLE>

As of February 28, 2006, there were approximately 228 holders of record of
our common stock.

We have never paid cash dividends on our common stock. We anticipate that
we will retain all of our future earnings, if any, for use in the expansion and
operation of our business and do not anticipate paying cash dividends in the
foreseeable future.


20
ITEM 6. SELECTED FINANCIAL DATA

The statement of operations data for the years ended December 31, 2005,
2004 and 2003 and the balance sheet data as of December 31, 2005 and 2004 have
been derived from our audited financial statements included elsewhere in this
annual report on Form 10-K. The statements of operations data for the years
ended December 31, 2002 and 2001, and the balance sheet data as of December 31,
2003, 2002 and 2001 have been derived from our audited financial statements not
included in this annual report on Form 10-K. Our historical results are not
necessarily indicative of results to be expected for any future period. The data
presented below has been derived from financial statements that have been
prepared in accordance with accounting principles generally accepted in the
United States and should be read with our financial statements, including the
notes, and with "Management's Discussion and Analysis of Financial Condition and
Results of Operations" included elsewhere in this annual report on Form 10-K.

<TABLE>
<CAPTION>
YEAR ENDED DECEMBER 31,
-----------------------------------------------------
2005 2004 2003 2002 2001
--------- -------- -------- -------- --------
(in thousands, except per share data)
<S> <C> <C> <C> <C> <C>
STATEMENTS OF OPERATIONS DATA:
Revenues ........................................................... $ 75,680 $ 61,740 $ 42,838 $ 35,200 $ 30,577
Operating expenses:
Research and development, including stock-based
compensation of ($21) in 2005, $426 in 2004, $5,048 in
2003, $5,155 in 2002 and $5,539 in 2001 ...................... 93,625 90,586 82,198 74,859 53,355
General and administrative, including stock-based
compensation of $0 in 2005, $412 in 2004, $5,067 in
2003, $5,113 in 2002 and $5,231 in 2001 ...................... 18,174 18,608 23,233 23,234 20,861
-------- -------- -------- -------- --------
Total operating expenses ........................................... 111,799 109,194 105,431 98,093 74,216
-------- -------- -------- -------- --------
Loss from operations ............................................... (36,119) (47,454) (62,593) (62,893) (43,639)
Interest and other income, net ..................................... (77) 282 1,471 3,223 8,467
-------- -------- -------- -------- --------
Loss before taxes and cumulative effect of a change in
accounting principle ............................................ (36,196) (47,172) (61,122) (59,670) (35,172)
Income tax provision ............................................... 119 -- -- -- --
-------- -------- -------- -------- --------
Loss before cumulative effect of a change in
accounting principle ............................................ (36,315) (47,172) (61,122) (59,670) (35,172)
Cumulative effect of a change in accounting principle (1) .......... -- -- (3,076) -- --
-------- -------- -------- -------- --------
Net loss ........................................................... $(36,315) $(47,172) $(64,198) $(59,670) $(35,172)
======== ======== ======== ======== ========
Net loss per common share basic and diluted:
Loss before cumulative effect of a change in accounting principle $ (0.57) (0.74) $ (1.08) (1.14) (0.70)
Cumulative effect of a change in accounting principle ........... -- -- (0.05) -- --
-------- -------- -------- -------- --------
Net loss per common share, basic and diluted ....................... $ (0.57) (0.74) $ (1.13) (1.14) (0.70)
======== ======== ======== ======== ========
Shares used in computing net loss per common
share, basic and diluted ..................................... 63,962 63,327 56,820 52,263 50,213
</TABLE>

<TABLE>
<CAPTION>
AS OF DECEMBER 31,
--------------------------------------------------------
2005 2004 2003 2002 2001
--------- --------- --------- --------- --------
(in thousands)
<S> <C> <C> <C> <C> <C>
BALANCE SHEET DATA:
Cash, cash equivalents and investments, including restricted
cash and investments of $430 in 2005, $430 in 2004,
$57,514 in 2003, $57,710 in 2002 and $43,338 in 2001 .... $ 99,695 $ 87,558 $ 161,001 $ 123,096 $166,840
Working capital ............................................ 48,584 60,038 139,739 111,833 147,663
Total assets ............................................... 218,714 211,980 284,199 201,772 239,990
Long-term debt, net of current portion ..................... 32,189 32,940 56,344 4,000 --
Accumulated deficit ........................................ (297,430) (261,115) (213,943) (149,745) (90,075)
Stockholders' equity ....................................... 85,802 121,594 166,216 169,902 218,372
</TABLE>

- ----------
(1) Upon adoption of FASB Interpretation No. 46, or FIN 46, "Consolidation of
Variable Interest Entities - An Interpretation of ARB No. 51," the Company
consolidated the assets of the variable interest entity, which were
comprised of property and improvements funded under a synthetic lease.
These assets had a carrying value of $54.8 million, net of accumulated
depreciation of $3.1 million on December 31, 2003. The Company also
consolidated the variable interest entity's debt of $52.3 million and
non-controlling interests of $2.5 million, which amounts are included in
long-term debt and other long-term liabilities, respectively. Additionally,
the Company recorded a cumulative effect of a change in accounting
principle equal to the accumulated depreciation of $3.1 million for the
period from the date the buildings were placed in service under the
synthetic lease through December 31, 2003. In April 2004, Lexicon purchased
the facilities subject to the synthetic lease, repaying the amounts funded
under the synthetic lease with proceeds from a mortgage financing and cash.


21
ITEM 7. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS
OF OPERATIONS

The following discussion and analysis should be read with "Selected
Financial Data" and our financial statements and notes included elsewhere in
this annual report on Form 10-K.

OVERVIEW

We are a biopharmaceutical company focused on the discovery and development
of breakthrough treatments for human disease. We are using gene knockout
technology to systematically discover the physiological functions of genes in
living mammals, or in vivo. We generate our gene function discoveries using
knockout mice - mice whose DNA has been altered to disrupt, or "knock out," the
function of the altered gene. Our patented gene trapping and gene targeting
technologies enable us to rapidly generate these knockout mice by altering the
DNA of genes in a special variety of mouse cells, called embryonic stem cells,
which can be cloned and used to generate mice with the altered gene. We employ
an integrated platform of advanced medical technologies to systematically
discover and validate which genes, when knocked out, result in a favorable
medical profile with pharmaceutical utility. We then pursue those genes and the
proteins they encode as potential targets for therapeutic intervention in our
drug discovery programs.

We employ internal resources and drug discovery alliances to discover
potential small molecule, antibody and protein drugs for in vivo-validated drug
targets that we consider to have high pharmaceutical value. We use our own
sophisticated libraries of drug-like chemical compounds and an industrialized
medicinal chemistry platform to identify small molecule drug candidates for our
in vivo-validated drug targets. We have established alliances with Bristol-Myers
Squibb Company to discover and develop novel small molecule drugs in the
neuroscience field; with Genentech, Inc. for the discovery of therapeutic
proteins and antibody targets and the development of antibody and protein drugs
based on those targets; with N.V. Organon for the discovery of another group of
therapeutic proteins and antibody targets and the development and
commercialization of antibody and protein drugs based on those targets; and with
Takeda Pharmaceutical Company Limited to discover new drugs for the treatment of
high blood pressure. In addition, we have established collaborations and license
agreements with other leading pharmaceutical and biotechnology companies under
which we receive fees and, in some cases, are eligible to receive milestone and
royalty payments, for access to some of our technologies and discoveries for use
in their own drug discovery efforts.

We derive substantially all of our revenues from drug discovery alliances,
target validation collaborations for the development and, in some cases,
analysis of the physiological effects of genes altered in knockout mice,
government grants and contracts, and technology licenses. To date, we have
generated a substantial portion of our revenues from a limited number of
sources.

Our operating results and, in particular, our ability to generate
additional revenues are dependent on many factors, including our success in
establishing collaborations, alliances and technology licenses, expirations of
our collaborations and alliances, the success rate of our discovery efforts
leading to opportunities for new collaborations, alliances and licenses, as well
as milestone payments and royalties, the timing and willingness of collaborators
to commercialize products which may result in royalties, and general and
industry-specific economic conditions which may affect research and development
expenditures. Our future revenues from collaborations, alliances and government
grants and contracts are uncertain because our existing agreements have fixed
terms or relate to specific projects of limited duration. Our future revenues
from technology licenses are uncertain because they depend, in large part, on
securing new agreements. Subject to limited exceptions, we do not intend to
offer subscriptions to our databases or make our compound libraries available
for purchase in the future. Our ability to secure future revenue-generating
agreements will depend upon our ability to address the needs of our potential
future collaborators, grantees, and licensees, and to negotiate agreements that
we believe are in our long-term best interests. We may determine that our
interests are better served by retaining rights to our discoveries and advancing
our therapeutic programs to a later stage, which could limit our near-term
revenues. Because of these and other factors, our operating results have
fluctuated in the past and are likely to do so in the future, and we do not
believe that period-to-period comparisons of our operating results are a good
indication of our future performance.

Since our inception, we have incurred significant losses and, as of
December 31, 2005, we had an accumulated deficit of $297.4 million. Our losses
have resulted principally from costs incurred in research and development,
general and administrative costs associated with our operations, and non-cash
stock-based compensation expenses associated with stock options granted to
employees and consultants prior to our April 2000 initial public offering.
Research and development expenses consist primarily of salaries and related
personnel costs, material costs, facility costs, depreciation on property and
equipment, legal expenses resulting from intellectual


22
property prosecution and other expenses related to our drug discovery programs,
the development and analysis of knockout mice and our other target validation
research efforts, and the development of compound libraries. General and
administrative expenses consist primarily of salaries and related expenses for
executive and administrative personnel, professional fees and other corporate
expenses including information technology, facilities costs and general legal
activities. In connection with the expansion of our drug discovery programs and
our target validation research efforts, we expect to incur increasing research
and development and general and administrative costs. As a result, we will need
to generate significantly higher revenues to achieve profitability.

As of December 31, 2005 we had net operating loss carryforwards of
approximately $184.7 million. We also had research and development tax credit
carryforwards of approximately $12.4 million. The net operating loss and credit
carryforwards will expire at various dates beginning in 2011, if not utilized.
Utilization of the net operating losses and credits may be significantly limited
due to a change in ownership as defined by provisions of the Internal Revenue
Code of 1986 and similar state provisions. The annual limitation may result in
the expiration of net operating losses and credits before utilization. We
recorded a $119,000 income tax provision representing current alternative
minimum tax payable based on taxable income for the year ended December 31,
2005.

CRITICAL ACCOUNTING POLICIES

REVENUE RECOGNITION

We recognize revenues when persuasive evidence of an arrangement exists,
delivery has occurred or services have been rendered, the price is fixed and
determinable, and collectibility is reasonably assured. Payments received in
advance under these arrangements are recorded as deferred revenue until earned.

Upfront fees under our drug discovery alliances are recognized as revenue
on a straight-line basis over the estimated period of service, generally the
contractual research term, to the extent they are non-refundable. Research
funding under these alliances is recognized as services are performed to the
extent they are non-refundable, either on a straight-line basis over the
estimated service period, generally the contractual research term; or as
contract research costs are incurred. Milestone-based fees are recognized upon
completion of specified milestones according to contract terms. Fees for access
to our databases and other target validation resources are recognized ratably
over the subscription or access period. Payments received under target
validation collaborations and government grants and contracts are recognized as
revenue as we perform our obligations related to such research to the extent
such fees are non-refundable. Non-refundable technology license fees are
recognized as revenue upon the grant of the license when performance is complete
and there is no continuing involvement.

Revenues recognized from multiple element contracts are allocated to each
element of the arrangement based on the relative fair value of the elements. The
determination of fair value of each element is based on objective evidence. When
revenues for an element are specifically tied to a separate earnings process,
revenue is recognized when the specific performance obligation associated with
the element is completed. When revenues for an element are not specifically tied
to a separate earnings process, they are recognized ratably over the term of the
agreement.

A change in our revenue recognition policy or changes in the terms of
contracts under which we recognize revenues could have an impact on the amount
and timing of our recognition of revenues.

RESEARCH AND DEVELOPMENT EXPENSES

Research and development expenses consist of costs incurred for
company-sponsored as well as collaborative research and development activities.
These costs include direct and research-related overhead expenses and are
expensed as incurred. Patent costs and technology license fees for technologies
that are utilized in research and development and have no alternative future use
are expensed when incurred.

We have advanced two of our drug discovery programs, LX-6171 and LX-1031,
into preclinical development in preparation for regulatory filings for the
commencement of clinical trials. The drug development process takes many years
to complete. The cost and length of time varies due to many factors, including
the type, complexity and intended use of the product candidate. We estimate that
drug development activities are typically completed over the following periods:


23
<TABLE>
<CAPTION>
PHASE ESTIMATED COMPLETION PERIOD
- ----------------------- ---------------------------
<S> <C>
Preclinical development 1-2 years
Phase 1 clinical trials 1-2 years
Phase 2 clinical trials 1-2 years
Phase 3 clinical trials 2-4 years
</TABLE>

We expect research and development costs to increase in the future as our
drug discovery programs advance in preclinical development and clinical trials.
Due to the variability in the length of time necessary for drug development, the
uncertainties related to the cost of these activities and ultimate ability to
obtain governmental approval for commercialization, accurate and meaningful
estimates of the ultimate costs to bring our potential product candidates to
market are not available.

We record our research and development costs by type or category, rather
than by project. Significant categories of costs include personnel, facilities
and equipment costs, laboratory supplies and third-party and other services. In
addition, a significant portion of our research and development expenses is not
tracked by project as it benefits multiple projects. Consequently, fully-loaded
research and development cost summaries by project are not available.

GOODWILL IMPAIRMENT

Goodwill is not amortized, but is tested at least annually for impairment
at the reporting unit level. We have determined that the reporting unit is the
single operating segment disclosed in our current financial statements.
Impairment is the condition that exists when the carrying amount of goodwill
exceeds its implied fair value. The first step in the impairment process is to
determine the fair value of the reporting unit and then compare it to the
carrying value, including goodwill. We determined that the market capitalization
approach is the most appropriate method of measuring fair value of the reporting
unit. Under this approach, fair value is calculated as the average closing price
of our common stock for the 30 days preceding the date that the annual
impairment test is performed, multiplied by the number of outstanding shares on
that date. A control premium, which is representative of premiums paid in the
marketplace to acquire a controlling interest in a company, is then added to the
market capitalization to determine the fair value of the reporting unit. If the
fair value exceeds the carrying value, no further action is required and no
impairment loss is recognized. Additional impairment assessments may be
performed on an interim basis if we encounter events or changes in circumstances
that would indicate that, more likely than not, the carrying value of goodwill
has been impaired. There was no impairment of goodwill in 2005.

RECENT ACCOUNTING PRONOUNCEMENT

In December 2004, the Financial Accounting Standards Board, or FASB, issued
Statement of Financial Accounting Standards No. 123 (Revised), "Share-Based
Payment," or SFAS 123 (Revised). The statement eliminates the ability to account
for stock-based compensation using Accounting Principles Board Opinion No. 25
and requires such transactions be recognized as compensation expense in the
income statement based on their fair values on the date of the grant, with the
compensation expense recognized over the period in which an employee is required
to provide service in exchange for the stock award. We adopted this statement on
January 1, 2006 using a modified prospective application. As such, the
compensation expense recognition provisions will apply to new awards and to any
awards modified, repurchased or canceled after the adoption date. Additionally,
for any unvested awards outstanding at the adoption date, we will recognize
compensation expense over the remaining vesting period. We are currently
evaluating the impact of SFAS 123 (Revised) on our financial condition and
results of operation. However, using a Black-Scholes option pricing model
consistent with our current practice, the adoption of SFAS 123 (Revised) on
January 1, 2006 is estimated to result in additional compensation expense of
approximately $7.0 million to $9.0 million for the year ended December 31, 2006.
This estimate is dependent upon market price, assumptions used in estimating the
fair value of stock options, and the level of stock option grants and
cancellations in 2006.


24
RESULTS OF OPERATIONS - COMPARISON OF YEARS ENDED DECEMBER 31, 2005, 2004 AND
2003

REVENUES

Total revenues and dollar and percentage changes as compared to the prior
year are as follows (dollar amounts are presented in millions):

<TABLE>
<CAPTION>
YEAR ENDED DECEMBER 31,
-----------------------
2005 2004 2003
----- ----- -----
<S> <C> <C> <C>
Total revenues ....... $75.7 $61.7 $42.8
Dollar increase ...... $14.0 $18.9
Percentage increase .. 23% 44%
</TABLE>

Years Ended December 31, 2005 and 2004

- Collaborative research - Revenue from collaborative research increased
40% in 2005 to $69.6 million, primarily due to the commencement in May
2005 of our alliance with Organon, our completion of two performance
milestones under our alliance with Genentech, and our award from the
Texas Enterprise Fund. Revenue in 2004 included performance milestone
payments under our Genentech and Takeda alliances as well as revenues
recognized under our therapeutic protein discovery alliance with
Incyte, for which the collaboration period ended in June 2004.

- Subscription and license fees - Revenue from subscriptions and license
fees decreased 49% in 2005 to $6.1 million due to the expiration of
Bristol-Myers Squibb's and Incyte's subscriptions to our LexVision
database in December 2004 and June 2004, respectively. This was offset
in part by higher technology license fees in the current year.

Years Ended December 31, 2004 and 2003

- Collaborative research - Revenue from collaborative research increased
134% in 2004 to $49.7 million, primarily due to increased revenue
under our alliance with Bristol-Myers Squibb, which commenced in
December 2003, our completion of a performance milestone under our
alliance with Genentech, and the commencement in July 2004 of our
alliance with Takeda. This was offset in part by a decrease in
revenues from target validation collaborations due to the scheduled
conclusion of many of these arrangements and the expiration of the
collaboration period under our alliance with Incyte in June 2004.

- Subscription and license fees - Revenue from subscriptions and license
fees decreased 44% in 2004 to $12.0 million, due to decreased
technology license fees and the expiration of Incyte's subscription to
our LexVision database in June 2004.

In 2005, Bristol-Myers Squibb, Genentech and Organon represented 34%, 30%
and 16% of revenues, respectively. In 2004, Bristol-Myers Squibb, Genentech and
Incyte represented 43%, 26% and 8% of revenues, respectively. In 2003, Incyte,
Amgen, Inc., Bristol-Myers Squibb and Genentech represented 23%, 15%, 14% and
14% of revenues, respectively.

RESEARCH AND DEVELOPMENT EXPENSES

Research and development expenses and dollar and percentage changes as
compared to the prior year are as follows (dollar amounts are presented in
millions):

<TABLE>
<CAPTION>
YEAR ENDED DECEMBER 31,
-----------------------
2005 2004 2003
----- ----- -----
<S> <C> <C> <C>
Total research and development expense .. $93.6 $90.6 $82.2
Dollar increase ......................... $ 3.0 $ 8.4
Percentage increase ..................... 3% 10%
</TABLE>

Research and development expenses consist primarily of salaries and other
personnel-related expenses, facility and equipment costs, laboratory supplies,
third-party and other services and stock-based compensation expenses.


25
Years Ended December 31, 2005 and 2004

- Personnel - Personnel costs increased 7% in 2005 to $46.3 million,
primarily due to increased personnel to support the expansion of our
drug discovery programs and merit-based pay increases for employees.
Salaries, bonuses, employee benefits, payroll taxes, recruiting and
relocation costs are included in personnel costs.

- Facilities and equipment - Facilities and equipment costs increased 4%
in 2005 to $21.0 million, primarily due to an increase in utility
costs.

- Laboratory supplies - Laboratory supplies expense decreased 4% in 2005
to $13.5 million, primarily due to decreased purchases of specialty
reagents and compounds.

- Third-party and other services - Third-party and other services
decreased 4% in 2005 to $7.2 million, primarily due to the termination
of our subscription to a third-party database offset, in part, by an
increase in third-party research costs. Third-party and other services
include third-party research, subscriptions to third-party databases,
technology licenses, legal and patent fees.

- Stock-based compensation - Stock-based compensation expense decreased
by $0.4 million in 2005 due to the fact that all deferred stock
compensation related to option grants made prior to our April 2000
initial public offering was fully amortized as of January 31, 2004.

- Other - Other costs increased by 11% in 2005 to $5.6 million.

Years Ended December 31, 2004 and 2003

- Personnel - Personnel costs increased 24% in 2004 to $43.3 million,
primarily due to increased personnel to support the expansion of our
drug discovery programs, merit-based pay increases for employees and
increasing employee benefit costs.

- Facilities and equipment - Facilities and equipment costs increased 2%
in 2004 to $20.2 million, primarily due to an increase in depreciation
expense on our facilities in The Woodlands, Texas. The increase was
offset, in part, by the elimination of rent expense for those
facilities as a result of our consolidation of the lessor under our
synthetic lease on December 31, 2003 and subsequent refinancing of
those facilities as well as the January 2004 expiration of the lease
for our former facility in East Windsor, New Jersey.

- Laboratory supplies - Laboratory supplies expense increased 27% in
2004 to $14.1 million, primarily due to increased purchases of
consumables and other supplies related to our drug discovery
activities, as well as compound acquisitions.

- Third-party and other services - Third-party and other services
increased 7% in 2004 to $7.5 million, primarily due to an increase in
third-party research costs offset, in part, by the termination of our
subscription to a third-party database.

- Stock-based compensation - Stock-based compensation expense, primarily
relating to option grants made prior to our April 2000 initial public
offering, decreased 92% in 2004 to $0.4 million. All deferred stock
compensation relating to these options was fully amortized as of
January 31, 2004, when these options became fully vested.

- Other - Other costs increased by 17% in 2004 to $5.0 million.

GENERAL AND ADMINISTRATIVE EXPENSES

General and administrative expenses and dollar and percentage changes as
compared to the prior year are as follows (dollar amounts are presented in
millions):

<TABLE>
<CAPTION>
YEAR ENDED DECEMBER 31,
-----------------------
2005 2004 2003
----- ----- -----
<S> <C> <C> <C>
Total general and administrative expense .. $18.2 $18.6 $23.2
Dollar decrease ........................... $ 0.4 $ 4.6
Percentage decrease ....................... 2% 20%
</TABLE>


26
General and administrative expenses consist primarily of personnel costs to
support our research activities, facility and equipment costs, professional fees
such as legal fees, and stock-based compensation expenses.

Years Ended December 31, 2005 and 2004

- Personnel - Personnel costs increased 2% in 2005 to $10.8 million.
Salaries, bonuses, employee benefits, payroll taxes, recruiting and
relocation costs are included in personnel costs.

- Facilities and equipment - Facilities and equipment costs were $3.1
million in 2005, consistent with the prior year.

- Professional fees - Professional fees decreased 10% in 2005 to $1.9
million, primarily due to decreased litigation costs.

- Stock-based compensation - Stock-based compensation expense decreased
by $0.4 million in 2005 due to the fact that all deferred stock
compensation related to option grants made prior to our April 2000
initial public offering was fully amortized as of January 31, 2004.

- Other - Other costs were $2.4 million in 2005, consistent with the
prior year.

Years Ended December 31, 2004 and 2003

- Personnel - Personnel costs were $10.6 million in 2004, consistent
with the prior year.

- Facilities and equipment - Facilities and equipment costs decreased
15% in 2004 to $3.1 million, primarily due to the elimination of rent
expense on our facilities in The Woodlands, Texas as a result of our
consolidation of the lessor under our synthetic lease on December 31,
2003 and subsequent refinancing of those facilities, as well as the
January 2004 expiration of the lease for our former facility in East
Windsor, New Jersey.

- Professional fees - Professional fees increased 30% in 2004 to $2.1
million, primarily due to increased board of director, audit and
consulting fees.

- Stock-based compensation - Stock-based compensation expense, primarily
relating to option grants made prior to our April 2000 initial public
offering, decreased 92% in 2004 to $0.4 million. All deferred stock
compensation relating to these options was fully amortized as of
January 31, 2004, when these options became fully vested.

- Other - Other costs increased 6% in 2004 to $2.4 million.

INTEREST INCOME, INTEREST EXPENSE AND OTHER INCOME, NET

Interest Income. Interest income increased 61% in 2005 to $2.6 million from
$1.6 million in 2004 and 2003, primarily due to higher interest rates.

Interest Expense. Interest expense increased 23% in 2005 to $3.3 million
from $2.7 million in 2004, and 718% in 2004 from $0.3 million in 2003. In April
2004, we purchased our facilities in The Woodlands, Texas from the lessor under
our previous synthetic lease agreement, using the proceeds from a $34.0 million
mortgage and cash. Interest expense increased in 2005 as compared to 2004 as a
result of a full year of interest expense under the mortgage. Interest expense
increased in 2004 as compared to 2003 as a result of the mortgage and the fact
that, prior to our consolidation of the lessor under the synthetic lease on
December 31, 2003, interest expense incurred under the synthetic lease was
recorded as rent expense.

Other Income. Other income decreased 57% in 2005 to $0.6 million from $1.3
million in 2004, and increased 441% in 2004 from $0.2 million in 2003. Other
income in 2004 included a settlement with our former insurance provider for a
disputed claim under our insurance policy.


27
NET LOSS AND NET LOSS PER COMMON SHARE

Loss and Loss per Common Share before Cumulative Effect of a Change in
Accounting Principle. Loss before a change in accounting principle decreased to
$36.3 million in 2005 from $47.2 million in 2004 and $61.1 million in 2003. Loss
per common share before a change in accounting principle decreased to $0.57 in
2005 from $0.74 in 2004 and $1.08 in 2003. Loss before a change in accounting
principle includes stock-based compensation expense of $0.8 million and $10.1
million in 2004 and 2003, respectively.

Change in Accounting Principle. We adopted Financial Accounting Standards
Board Interpretation No. 46, "Consolidation of Variable Interest Entities - An
Interpretation of ARB No. 51," or FIN 46, on December 31, 2003. We determined
that the lessor under the synthetic lease is a variable interest entity as
defined by FIN 46, and that we absorb a majority of the variable interest
entity's expected losses. Accordingly, we recorded a cumulative effect of a
change in accounting principle equal to the accumulated depreciation of $3.1
million for the period from the date the buildings were placed in service under
the synthetic lease through December 31, 2003.

Net Loss and Net Loss per Common Share. Net loss decreased to $36.3 million
in 2005 from $47.2 million in 2004 and $64.2 million in 2003. Net loss per
common share decreased to $0.57 in 2005 from $0.74 in 2004 and $1.13 in 2003.

LIQUIDITY AND CAPITAL RESOURCES

We have financed our operations from inception primarily through sales of
common and preferred stock, contract and milestone payments to us under our drug
discovery alliance, target validation, database subscription, and license
agreements, government grants and contracts, and financing obtained under debt
and lease arrangements. From our inception through December 31, 2005, we had
received net proceeds of $295.4 million from issuances of common and preferred
stock, including $203.2 million of net proceeds from the initial public offering
of our common stock in April 2000 and $50.1 million from our July 2003 common
stock offering. In addition, from our inception through December 31, 2005, we
received $347.4 million in cash payments from drug discovery alliances, target
validation collaborations, database subscription and technology license fees,
sales of compound libraries and reagents and government grants and contracts, of
which $268.7 million had been recognized as revenues through December 31, 2005.

As of December 31, 2005, we had $99.7 million in cash, cash equivalents and
short-term investments (including $0.4 million of restricted investments), as
compared to $87.6 million (including $0.4 million of restricted cash and
investments) as of December 31, 2004. Cash of $23.4 million was provided by
operations in 2005. This consisted primarily of the net loss for the year of
$36.3 million offset by non-cash charges of $10.4 million related to
depreciation expense and $1.2 million related to amortization of intangible
assets other than goodwill; a $44.0 million increase in deferred revenue; and
changes in other operating assets and liabilities of $4.1 million. Investing
activities used cash of $16.0 million, primarily due to purchases of property
and equipment of $11.3 million and net purchases of short-term investments of
$4.8 million. We used cash of $95,000 in financing activities. This consisted of
principal repayments of $0.7 million on the mortgage loan, offset by cash
proceeds of $0.6 million from stock option exercises.

In April 2004, we purchased our facilities in The Woodlands, Texas from the
lessor under our previous synthetic lease agreement. In connection with such
purchase, we repaid the $54.8 million funded under the synthetic lease with
proceeds from a $34.0 million third-party mortgage financing and $20.8 million
in cash. The mortgage loan has a ten-year term with a 20 year amortization and
bears interest at a fixed rate of 8.23%. As a result of the refinancing, all
restrictions on the cash and investments that had secured our obligations under
the synthetic lease were eliminated, leaving a total of $0.4 million in
restricted investments related to our New Jersey facility.

In May 2002, our subsidiary Lexicon Pharmaceuticals (New Jersey), Inc.
entered into a lease for a 76,000 square-foot facility in Hopewell, New Jersey.
The term of the lease extends until June 30, 2013. The lease provides for an
escalating yearly base rent payment of $1.3 million in the first year, $2.1
million in years two and three, $2.2 million in years four to six, $2.3 million
in years seven to nine and $2.4 million in years ten and eleven. We are the
guarantor of the obligations of our subsidiary under the lease.

In December 2002, we borrowed $4.0 million under a note agreement with
Genentech. The proceeds of the loan are to be used to fund research efforts
under our alliance with Genentech for the discovery of therapeutic proteins and
antibody targets. On November 30, 2005, the note agreement was amended to extend
the maturity date of the loan by one year to December 31, 2006. No other terms
of the note agreement were changed. We may repay


28
the note, at any time, at our option, in cash, in shares of our common stock
valued at the then-current market value, or in a combination of cash and shares,
subject to certain limitations. The note accrues interest at an annual rate of
8%, compounded quarterly.

Including the lease and debt obligations described above, we had incurred
the following contractual obligations as of December 31, 2005:

<TABLE>
<CAPTION>
PAYMENTS DUE BY PERIOD (IN MILLIONS)
---------------------------------------------------------
LESS THAN 1 MORE THAN 5
CONTRACTUAL OBLIGATIONS TOTAL YEAR 1-3 YEARS 3-5 YEARS YEARS
- ----------------------- ----- ----------- --------- --------- -----------
<S> <C> <C> <C> <C> <C>
Debt .......................... $37.0 $ 4.8 $ 1.7 $ 2.0 $28.5
Interest payment obligations .. 21.7 4.2 5.2 4.9 7.4
Operating leases .............. 18.5 2.3 4.8 5.0 6.4
----- ----- ----- ----- -----
Total ...................... $77.2 $11.3 $11.7 $11.9 $42.3
===== ===== ===== ===== =====
</TABLE>

Our future capital requirements will be substantial and will depend on many
factors, including our ability to obtain alliance, collaboration and technology
license agreements, the amount and timing of payments under such agreements, the
level and timing of our research and development expenditures, market acceptance
of our products, the resources we devote to developing and supporting our
products and other factors. Our capital requirements will also be affected by
any expenditures we make in connection with license agreements and acquisitions
of and investments in complementary technologies and businesses. We expect to
devote substantial capital resources to continue our research and development
efforts, to expand our support and product development activities, and for other
general corporate activities. We believe that our current unrestricted cash and
investment balances and cash and revenues we expect to derive from drug
discovery alliances, target validation collaborations, government grants and
contracts, and technology licenses will be sufficient to fund our operations for
approximately the next two years. During or after this period, if cash generated
by operations is insufficient to satisfy our liquidity requirements, we will
need to sell additional equity or debt securities or obtain additional credit
arrangements. Additional financing may not be available on terms acceptable to
us or at all. The sale of additional equity or convertible debt securities may
result in additional dilution to our stockholders.

DISCLOSURE ABOUT MARKET RISK

We are exposed to limited market and credit risk on our cash equivalents
which have maturities of three months or less. We maintain a short-term
investment portfolio which consists of U.S. government agency debt obligations,
investment grade commercial paper, corporate debt securities and certificates of
deposit that mature three to twelve months from the time of purchase and auction
rate securities that mature greater than twelve months from the time of
purchase, which we believe are subject to limited market and credit risk. We
currently do not hedge interest rate exposure or hold any derivative financial
instruments in our investment portfolio.

We have operated primarily in the United States and substantially all sales
to date have been made in U.S. dollars. Accordingly, we have not had any
material exposure to foreign currency rate fluctuations.

ITEM 7A. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

See "Disclosure about Market Risk" under "Item 7. Management's Discussion
and Analysis of Financial Condition and Results of Operations" for quantitative
and qualitative disclosures about market risk.

ITEM 8. FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

The financial statements required by this Item are incorporated under Item
15 in Part IV of this report.

ITEM 9. CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND
FINANCIAL DISCLOSURE.

None.

ITEM 9A. CONTROLS AND PROCEDURES

Our chief executive officer and chief financial officer have concluded that
our disclosure controls and procedures (as defined in rules 13a-15(e) and
15d-15(e) under the Securities Exchange Act of 1934) are sufficiently effective
to ensure that the information required to be disclosed by us in the reports we
file under the Securities

29
Exchange Act is gathered, analyzed and disclosed with adequate timeliness,
accuracy and completeness, based on an evaluation of such controls and
procedures as of the end of the period covered by this report.

Subsequent to our evaluation, there were no significant changes in internal
controls or other factors that could significantly affect internal controls,
including any corrective actions with regard to significant deficiencies and
material weaknesses.

MANAGEMENT REPORT ON INTERNAL CONTROL OVER FINANCIAL REPORTING

Our management is responsible for establishing and maintaining adequate
internal control over financial reporting (as defined in Rules 13a-15(f) and
15d-15(f) under the Securities Exchange Act of 1934).

Because of its inherent limitations, internal control over financial
reporting may not prevent or detect misstatements. 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.

Our management assessed the effectiveness of our internal control over
financial reporting as of December 31, 2005. In making this assessment,
management used the criteria set forth by the Committee of Sponsoring
Organizations of the Treadway Commission in Internal Control-Integrated
Framework.

Based on such assessment using those criteria, management believes that, as
of December 31, 2005, our internal control over financial reporting is
effective.

Our independent auditors have issued an audit report on our assessment of
our internal control over financial reporting which appears on page F-2 and is
incorporated under Item 15 in Part IV of this report.


30
PART III

ITEM 10. DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT

The information required by this Item as to our directors and executive
officers is hereby incorporated by reference from the information appearing
under the captions "Stock Ownership of Certain Beneficial Owners and Management
- - Section 16(a) Beneficial Ownership Reporting Compliance," "Election of
Directors" and "Executive Compensation - Executive Officers" in our definitive
proxy statement which involves the election of directors and is to be filed with
the Securities and Exchange Commission pursuant to the Securities Exchange Act
of 1934 within 120 days of the end of our fiscal year on December 31, 2005.

ITEM 11. EXECUTIVE COMPENSATION

The information required by this Item as to our management is hereby
incorporated by reference from the information appearing under the captions
"Executive Compensation" and "Election of Directors - Director Compensation" in
our definitive proxy statement which involves the election of directors and is
to be filed with the Commission pursuant to the Securities Exchange Act of 1934
within 120 days of the end of our fiscal year on December 31, 2005.
Notwithstanding the foregoing, in accordance with the instructions to Item 402
of Regulation S-K, the information contained in our proxy statement under the
sub-heading "Report of the Compensation Committee of the Board of Directors" and
"Performance Graph" shall not be deemed to be filed as part of or incorporated
by reference into this annual report on Form 10-K.

ITEM 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT AND
RELATED STOCKHOLDER MATTERS

The information required by this Item as to the ownership by management and
others of our securities is hereby incorporated by reference from the
information appearing under the captions "Stock Ownership of Certain Beneficial
Owners and Management" and "Equity Compensation Plan Information" in our
definitive proxy statement which involves the election of directors and is to be
filed with the Commission pursuant to the Securities Exchange Act of 1934 within
120 days of the end of our fiscal year on December 31, 2005.

ITEM 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS

The information required by this Item as to certain business relationships
and transactions with our management and other related parties is hereby
incorporated by reference from the information appearing under the captions
"Election of Directors - Certain Transactions with Directors" and "Election of
Directors - Compensation Committee Interlocks and Insider Participation" in our
definitive proxy statement which involves the election of directors and is to be
filed with the Commission pursuant to the Securities Exchange Act of 1934 within
120 days of the end of our fiscal year on December 31, 2005.

ITEM 14. PRINCIPAL ACCOUNTING FEES AND SERVICES

The information required by this Item as to the fees we pay our principal
accountant is hereby incorporated by reference from the information appearing
under the caption "Ratification and Approval of Independent Auditors -
Compensation of Independent Auditors" in our definitive proxy statement which
involves the election of directors and is to be filed with the Commission
pursuant to the Securities Exchange Act of 1934 within 120 days of the end of
our fiscal year on December 31, 2005.


31
PART IV

ITEM 15. EXHIBITS AND FINANCIAL STATEMENT SCHEDULES

(a) Documents filed as a part of this report:

1. Consolidated Financial Statements

<TABLE>
<CAPTION>
PAGE
----
<S> <C>
Report of Independent Registered Public Accounting Firm.................. F-1
Report of Independent Registered Public Accounting Firm.................. F-2
Consolidated Balance Sheets.............................................. F-3
Consolidated Statements of Operations.................................... F-4
Consolidated Statements of Stockholders' Equity.......................... F-5
Consolidated Statements of Cash Flows.................................... F-6
Notes to Consolidated Financial Statements............................... F-7
</TABLE>

All other financial statement schedules are omitted because they are
not applicable or not required, or because the required information is
included in the financial statements or notes thereto.

2. Exhibits

<TABLE>
<CAPTION>
EXHIBIT NO. DESCRIPTION
- ----------- -----------
<S> <C>
3.1 -- Restated Certificate of Incorporation (filed as Exhibit 3.1 to
the Company's Registration Statement on Form S-1 (Registration
No. 333-96469) and incorporated by reference herein).

3.2 -- Restated Bylaws (filed as Exhibit 3.2 to the Company's
Registration Statement on Form S-1 (Registration No. 333-96469)
and incorporated by reference herein).

*10.1 -- Restated Employment Agreement with Arthur T. Sands, M.D., Ph.D.

10.2 -- Employment Agreement with James R. Piggott, Ph.D. (filed as
Exhibit 10.2 to the Company's Registration Statement on Form S-1
(Registration No. 333-96469) and incorporated by reference
herein).

10.3 -- Employment Agreement with Jeffrey L. Wade, J.D. (filed as Exhibit
10.3 to the Company's Registration Statement on Form S-1
(Registration No. 333-96469) and incorporated by reference
herein).

10.4 -- Employment Agreement with Brian P. Zambrowicz, Ph.D. (filed as
Exhibit 10.4 to the Company's Registration Statement on Form S-1
(Registration No. 333-96469) and incorporated by reference
herein).

10.5 -- Employment Agreement with Julia P. Gregory (filed as Exhibit 10.5
to the Company's Registration Statement on Form S-1 (Registration
No. 333-96469) and incorporated by reference herein).

10.6 -- Employment Agreement with Alan Main, Ph.D. (filed as Exhibit 10.1
to the Company's Quarterly Report on Form 10-Q for the period
ended September 30, 2001 and incorporated by reference herein).

10.7 -- Consulting Agreement with Alan S. Nies, M.D. dated February 19,
2003, as amended (filed as Exhibit 10.1 to the Company's
Quarterly Report on Form 10-Q for the period ended March 31, 2004
and incorporated by reference herein).

10.8 -- Consulting Agreement with Robert J. Lefkowitz, M.D. dated March
31, 2003 (filed as Exhibit 10.1 to the Company's Quarterly Report
on Form 10-Q for the period ended March 31, 2003 and incorporated
by reference herein).
</TABLE>


32
<TABLE>
<CAPTION>
EXHIBIT NO. DESCRIPTION
- ----------- -----------
<S> <C>
10.9 -- Consulting Agreement with C. Thomas Caskey, M.D. dated March 28,
2005 (filed as Exhibit 10.1 to the Company's Quarterly Report on
Form 10-Q for the period ended March 31, 2005 and incorporated by
reference herein).

10.10 -- Form of Indemnification Agreement with Officers and Directors
(filed as Exhibit 10.7 to the Company's Registration Statement on
Form S-1 (Registration No. 333-96469) and incorporated by
reference herein).

*10.11 -- Summary of Non-Employee Director Compensation.

*10.12 -- Summary of 2006 Named Executive Officer Cash Compensation.

10.13 -- 2000 Equity Incentive Plan (filed as Exhibit 10.10 to the
Company's Annual Report on Form 10-K for the period ended
December 31, 2004 and incorporated by reference herein).

*10.14 -- 2000 Non-Employee Directors' Stock Option Plan.

10.15 -- Coelacanth Corporation 1999 Stock Option Plan (filed as Exhibit
99.1 to the Company's Registration Statement on Form S-8
(Registration No. 333-66380) and incorporated by reference
herein).

10.16 -- Form of Stock Option Agreement with Officers under the 2000
Equity Incentive Plan (filed as Exhibit 10.2 to the Company's
Quarterly Report on Form 10-Q for the period ended September 30,
2004 and incorporated by reference herein).

*10.17 -- Form of Stock Option Agreement with Chairman of Board of
Directors under the 2000 Equity Incentive Plan.

10.18 -- Form of Stock Option Agreement with Directors under the 2000
Non-Employee Directors' Stock Option Plan (filed as Exhibit 10.3
to the Company's Quarterly Report on Form 10-Q for the period
ended September 30, 2004 and incorporated by reference herein).

+10.19 -- Collaboration and License Agreement, dated December 17, 2003,
with Bristol-Myers Squibb Company (filed as Exhibit 10.15 to the
amendment to the Company's Annual Report on Form 10-K/A for the
period ended December 31, 2003, as filed on July 16, 2004, and
incorporated by reference herein).

+10.20 -- Collaboration Agreement, dated July 27, 2004, with Takeda
Pharmaceutical Company Limited (filed as Exhibit 10.1 to the
Company's Quarterly Report on Form 10-Q for the period ended
September 30, 2004 and incorporated by reference herein).

+10.21 -- Collaboration and License Agreement, dated May 16, 2005, with
N.V. Organon and (only with respect to Section 9.4 thereof)
Intervet Inc. (filed as Exhibit 10.1 to the Company's Quarterly
Report on Form 10-Q for the period ended June 30, 2005 and
incorporated by reference herein).

*+10.22 -- Second Amended and Restated Collaboration and License Agreement,
dated November 30, 2005, with Genentech, Inc.

10.23 -- Economic Development Agreement dated July 15, 2005, with the
State of Texas and the Texas A&M University System (filed as
Exhibit 10.1 to the Company's Quarterly Report on Form 10-Q for
the period ended September 30, 2005 and incorporated by reference
herein).

+10.24 -- Collaboration and License Agreement, dated July 15, 2005, with
the Texas A&M University System and the Texas Institute for
Genomic Medicine (filed as Exhibit 10.2 to the Company's
Quarterly Report on Form 10-Q for the period ended September 30,
2005 and incorporated by reference herein).

10.25 -- Loan and Security Agreement, dated April 21, 2004, between
Lex-Gen Woodlands, L.P. and iStar Financial Inc. (filed as
Exhibit 10.18 to the Company's Annual Report
</TABLE>


33
<TABLE>
<CAPTION>
EXHIBIT NO. DESCRIPTION
- ----------- -----------
<S> <C>
on Form 10-K for the period ended December 31, 2004 and
incorporated by reference herein).

10.26 -- Lease Agreement, dated May 23, 2002, between Lexicon
Pharmaceuticals (New Jersey), Inc. and Townsend Property Trust
Limited Partnership (filed as Exhibit 10.2 to the Company's
Quarterly Report on Form 10-Q for the period ended June 30, 2002
and incorporated by reference herein).

21.1 -- Subsidiaries (filed as Exhibit 21.1 to the Company's Annual
Report on Form 10-K for the year ended December 31, 2004 and
incorporated by reference herein).

*23.1 -- Consent of Independent Registered Public Accounting Firm

*24.1 -- Power of Attorney (contained in signature page)

*31.1 -- Certification of CEO Pursuant to Section 302 of the
Sarbanes-Oxley Act of 2002

*31.2 -- Certification of CFO Pursuant to Section 302 of the
Sarbanes-Oxley Act of 2002

*32.1 -- Certification of CEO and CFO Pursuant to Section 906 of the
Sarbanes-Oxley Act of 2002
</TABLE>

- ----------
* Filed herewith.

+ Confidential treatment has been requested for a portion of this exhibit.
The confidential portions of this exhibit have been omitted and filed
separately with the Securities and Exchange Commission.


34
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.

LEXICON GENETICS INCORPORATED


Date: March 3, 2006 By: /s/ ARTHUR T. SANDS
------------------------------------
Arthur T. Sands, M.D., Ph.D.
President and
Chief Executive Officer


Date: March 3, 2006 By: /s/ JULIA P. GREGORY
------------------------------------
Julia P. Gregory
Executive Vice President,
Corporate Development and
Chief Financial Officer

POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature
appears below constitutes and appoints Julia P. Gregory and Jeffrey L. Wade, or
either of them, each with the power of substitution, his or her
attorney-in-fact, to sign any amendments to this Form 10-K, and to file the
same, with exhibits thereto and other documents in connection therewith, with
the Securities and Exchange Commission, here ratifying and confirming all that
each of said attorneys-in-fact, or his or her substitute or substitutes, may do
or cause to be done by virtue hereof.

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.

<TABLE>
<CAPTION>
SIGNATURE TITLE DATE
--------- ----- ----
<S> <C> <C>


/S/ ARTHUR T. SANDS President and March 3, 2006
- ------------------------------- Chief Executive Officer
Arthur T. Sands, M.D., Ph.D. (Principal Executive Officer)


/S/ JULIA P. GREGORY Executive Vice President, March 3, 2006
- ------------------------------- Corporate Development and
Julia P. Gregory Chief Financial Officer
(Principal Financial and
Accounting Officer)


/S/ SAM L. BARKER Chairman of the Board of March 3, 2006
- ------------------------------- Directors
Sam L. Barker, Ph.D.


/S/ C. THOMAS CASKEY Director March 3, 2006
- -------------------------------
C. Thomas Caskey, M.D.


/S/ PATRICIA M. CLOHERTY Director March 3, 2006
- -------------------------------
Patricia M. Cloherty


/S/ ROBERT J. LEFKOWITZ Director March 3, 2006
- -------------------------------
Robert J. Lefkowitz, M.D.


/S/ ALAN S. NIES Director March 3, 2006
- -------------------------------
Alan S. Nies, M.D.


/S/ FRANK PALANTONI Director March 3, 2006
- -------------------------------
Frank Palantoni


/S/ CLAYTON S. ROSE Director March 3, 2006
- -------------------------------
Clayton S. Rose
</TABLE>


35
REPORT OF INDEPENDENT
REGISTERED PUBLIC ACCOUNTING FIRM

To the Board of Directors and Stockholders of Lexicon Genetics Incorporated:

We have audited the accompanying consolidated balance sheets of Lexicon Genetics
Incorporated and subsidiaries (the Company) as of December 31, 2005 and 2004,
and the related consolidated statements of operations, stockholders' equity and
cash flows for each of the three years in the period ended December 31, 2005.
These financial statements are the responsibility of the Company's management.
Our responsibility is to express an opinion on these financial statements based
on our 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 audit to obtain reasonable assurance about whether the financial
statements are free of material misstatement. An audit includes examining, on a
test basis, evidence supporting the amounts and disclosures in the financial
statements. An audit also includes assessing the accounting principles used and
significant estimates made by management, as well as evaluating the overall
financial statement presentation. We believe that our audits provide a
reasonable basis for our opinion.

In our opinion, the financial statements referred to above present fairly, in
all material respects, the consolidated financial position of Lexicon Genetics
Incorporated and subsidiaries as of December 31, 2005 and 2004, and the
consolidated results of its operations and its cash flows for each of the three
years in the period ended December 31, 2005, in conformity with U.S. generally
accepted accounting principles.

We also have audited, in accordance with the standards of the Public Company
Accounting Oversight Board (United States), the effectiveness of Lexicon
Genetics Incorporated's internal control over financial reporting as of December
31, 2005, based on criteria established in Internal Control--Integrated
Framework issued by the Committee of Sponsoring Organizations of the Treadway
Commission, and our report dated February 27, 2006 expressed an unqualified
opinion thereon.


/s/ ERNST & YOUNG LLP

Houston, Texas
February 27, 2006


F-1
REPORT OF INDEPENDENT
REGISTERED PUBLIC ACCOUNTING FIRM

To the Board of Directors and Stockholders of Lexicon Genetics Incorporated:

We have audited management's assessment, included in the accompanying Management
Report on Internal Control over Financial Reporting, that Lexicon Genetics
Incorporated (Lexicon) maintained effective internal control over financial
reporting as of December 31, 2005, based on criteria established in Internal
Control--Integrated Framework issued by the Committee of Sponsoring
Organizations of the Treadway Commission (the COSO criteria). Lexicon's
management is responsible for maintaining effective internal control over
financial reporting and for its assessment of the effectiveness of internal
control over financial reporting. Our responsibility is to express an opinion on
management's assessment and an opinion on the effectiveness of the company's
internal control over financial reporting based on our audit.

We conducted our audit in accordance with the standards of the Public Company
Accounting Oversight Board (United States). Those standards require that we plan
and perform the audit to obtain reasonable assurance about whether effective
internal control over financial reporting was maintained in all material
respects. Our audit included obtaining an understanding of internal control over
financial reporting, evaluating management's assessment, testing and evaluating
the design and operating effectiveness of internal control, and performing such
other procedures as we considered necessary in the circumstances. We believe
that our audit provides a reasonable basis for our opinion.

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 (1) pertain to
the maintenance of records that, in reasonable detail, accurately and fairly
reflect the transactions and dispositions of the assets of the company; (2)
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 (3) 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.

In our opinion, management's assessment that Lexicon Genetics Incorporated
maintained effective internal control over financial reporting as of December
31, 2005, is fairly stated, in all material respects, based on the COSO
criteria. Also, in our opinion, Lexicon Genetics Incorporated maintained, in all
material respects, effective internal control over financial reporting as of
December 31, 2005, based on the COSO criteria.

We also have audited, in accordance with the standards of the Public Company
Accounting Oversight Board (United States), the consolidated balance sheets of
Lexicon Genetics Incorporated and subsidiaries as of December 31, 2005 and 2004,
and the related consolidated statements of operations, stockholders' equity and
cash flows for each of the three years in the period ended December 31, 2005 of
Lexicon Genetics Incorporated and our report dated February 27, 2006 expressed
an unqualified opinion thereon.


/s/ ERNST & YOUNG LLP

Houston, Texas
February 27, 2006


F-2
LEXICON GENETICS INCORPORATED

CONSOLIDATED BALANCE SHEETS
(IN THOUSANDS, EXCEPT PAR VALUE)

<TABLE>
<CAPTION>
AS OF DECEMBER 31,
---------------------
2005 2004
--------- ---------
<S> <C> <C>
ASSETS
Current assets:
Cash and cash equivalents ............................................... $ 21,970 $ 14,612
Short-term investments, including restricted investments of $430 ........ 77,725 72,946
Accounts receivable, net of allowances of $45 and $75, respectively ..... 2,586 5,345
Other receivables ....................................................... 22 1,052
Prepaid expenses and other current assets ............................... 3,744 4,793
--------- ---------
Total current assets ................................................. 106,047 98,748
Property and equipment, net of accumulated depreciation and amortization
of $47,926 and $41,892, respectively .................................... 85,265 84,573
Goodwill ................................................................... 25,798 25,798
Intangible assets, net of amortization of $5,360 and $4,160, respectively... 640 1,840
Other assets ............................................................... 964 1,021
--------- ---------
Total assets ......................................................... $ 218,714 $ 211,980
========= =========
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities:
Accounts payable ........................................................ $ 6,883 $ 7,574
Accrued liabilities ..................................................... 6,787 6,945
Current portion of deferred revenue ..................................... 39,042 19,500
Current portion of long-term debt ....................................... 4,751 4,691
--------- ---------
Total current liabilities ............................................ 57,463 38,710
Deferred revenue, net of current portion ................................... 42,540 18,092
Long-term debt ............................................................. 32,189 32,940
Other long-term liabilities ................................................ 720 644
--------- ---------
Total liabilities .................................................... 132,912 90,386
Commitments and contingencies
Stockholders' equity:
Preferred stock, $.01 par value; 5,000 shares authorized;
no shares issued and outstanding ..................................... -- --
Common stock, $.001 par value; 120,000 shares authorized;
64,554 and 63,491 shares issued and outstanding, respectively ........ 64 63
Additional paid-in capital .............................................. 383,222 382,666
Deferred stock compensation ............................................. (2) (20)
Accumulated deficit ..................................................... (297,430) (261,115)
Accumulated other comprehensive loss .................................... (52) --
--------- ---------
Total stockholders' equity ........................................... 85,802 121,594
--------- ---------
Total liabilities and stockholders' equity ........................... $ 218,714 $ 211,980
========= =========
</TABLE>

The accompanying notes are an integral part of
these consolidated financial statements.


F-3
LEXICON GENETICS INCORPORATED

CONSOLIDATED STATEMENTS OF OPERATIONS
(IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)

<TABLE>
<CAPTION>
YEAR ENDED DECEMBER 31,
------------------------------
2005 2004 2003
-------- -------- --------
<S> <C> <C> <C>
Revenues:
Collaborative research .................................... $ 69,567 $ 49,736 $ 21,242
Subscription and license fees ............................. 6,113 12,004 21,550
Other ..................................................... -- -- 46
-------- -------- --------
Total revenues ......................................... 75,680 61,740 42,838
Operating expenses:
Research and development, including stock-based
compensation of $(21), $426, and $5,048, respectively .. 93,625 90,586 82,198
General and administrative, including stock-based
compensation of $0, $412, and $5,067 respectively ...... 18,174 18,608 23,233
-------- -------- --------
Total operating expenses ............................... 111,799 109,194 105,431
-------- -------- --------
Loss from operations ......................................... (36,119) (47,454) (62,593)
Interest income .............................................. 2,645 1,638 1,555
Interest expense ............................................. (3,280) (2,660) (325)
Other income, net ............................................ 558 1,304 241
-------- -------- --------
Loss before taxes and cumulative effect of a change
in accounting principle ................................... (36,196) (47,172) (61,122)
Income tax provision ......................................... 119 -- --
-------- -------- --------
Loss before cumulative effect of a change
in accounting principle ................................... (36,315) (47,172) (61,122)
Cumulative effect of a change in accounting principle ........ -- -- (3,076)
-------- -------- --------
Net loss ..................................................... $(36,315) $(47,172) $(64,198)
======== ======== ========
Net loss per common share basic and diluted:
Loss before cumulative effect of a
change in accounting principle ......................... $ (0.57) $ (0.74) $ (1.08)
Cumulative effect of a change in accounting principle ..... -- -- (0.05)
-------- -------- --------
Net loss per common share, basic and diluted .............. $ (0.57) $ (0.74) $ (1.13)
======== ======== ========
Shares used in computing net loss per common share,
basic and diluted ......................................... 63,962 63,327 56,820
</TABLE>

The accompanying notes are an integral part of
these consolidated financial statements.


F-4
LEXICON GENETICS INCORPORATED

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY
(IN THOUSANDS)

<TABLE>
<CAPTION>
ACCUMULATED
COMMON STOCK ADDITIONAL DEFERRED OTHER TOTAL
------------------ PAID-IN STOCK ACCUMULATED COMPREHENSIVE STOCKHOLDERS'
SHARES PAR VALUE CAPITAL COMPENSATION DEFICIT LOSS EQUITY
------ --------- ---------- ------------ ----------- ------------- -------------
<S> <C> <C> <C> <C> <C> <C> <C>
Balance at December 31, 2002 ........ 52,367 $52 $330,701 $(11,106) $(149,745) $ -- $169,902
Deferred stock compensation, net
of reversals ..................... -- -- (92) 92 -- -- --
Amortization of deferred stock
compensation ..................... -- -- -- 10,115 -- -- 10,115
Public offering of common stock,
net of offering costs ............ 10,240 10 50,147 -- -- -- 50,157
Exercise of common stock options .... 102 1 239 -- -- -- 240
Exercise of common stock warrants ... 118 -- -- -- -- -- --
Net and comprehensive loss .......... -- -- -- -- (64,198) -- (64,198)
------ --- -------- -------- --------- ---- --------
Balance at December 31, 2003 ........ 62,827 63 380,995 (899) (213,943) -- 166,216
Deferred stock compensation, net
of reversals ..................... -- -- (41) 41 -- -- --
Amortization of deferred stock
compensation ..................... -- -- -- 838 -- -- 838
Exercise of common stock options .... 664 -- 1,712 -- -- -- 1,712
Net and comprehensive loss .......... -- -- -- -- (47,172) -- (47,172)
------ --- -------- -------- --------- ---- --------
Balance at December 31, 2004 ........ 63,491 63 382,666 (20) (261,115) -- 121,594
Deferred stock compensation, net
of reversals ..................... -- -- (39) 39 -- -- --
Amortization of deferred stock
compensation ..................... -- -- -- (21) -- -- (21)
Exercise of common stock options .... 1,063 1 595 -- -- -- 596
Net loss ............................ -- -- -- -- (36,315) -- (36,315)
Unrealized loss on investments ...... -- -- -- -- -- (52) (52)
--------
Comprehensive loss .................. (36,367)
------ --- -------- -------- --------- ---- --------
Balance at December 31, 2005 ........ 64,554 $64 $383,222 $ (2) $(297,430) $(52) $ 85,802
====== === ======== ======== ========= ==== ========
</TABLE>

The accompanying notes are an integral part of
these consolidated financial statements.


F-5
LEXICON GENETICS INCORPORATED

CONSOLIDATED STATEMENTS OF CASH FLOWS
(IN THOUSANDS)

<TABLE>
<CAPTION>
YEAR ENDED DECEMBER 31,
---------------------------------
2005 2004 2003
--------- --------- ---------
<S> <C> <C> <C>
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss .......................................................... $ (36,315) $ (47,172) $ (64,198)
Adjustments to reconcile net loss to net cash used in operating
activities:
Depreciation ................................................... 10,456 10,834 10,215
Amortization of intangible assets, other than goodwill ......... 1,200 1,200 1,200
Amortization of deferred stock compensation .................... (21) 838 10,115
(Gain) loss on disposal of property and equipment .............. 10 (11) (18)
Cumulative effect of a change in accounting principle .......... -- -- 3,076
Changes in operating assets and liabilities:
(Increase) decrease in receivables .......................... 3,789 174 (1,428)
(Increase) decrease in prepaid expenses and other current
assets ................................................... 1,049 (860) 960
(Increase) decrease in other assets ......................... 57 (841) 1,060
Increase (decrease) in accounts payable and other
liabilities .............................................. (773) 3,682 2,257
Increase (decrease) in deferred revenue ..................... 43,990 (10,100) 29,045
--------- --------- ---------
Net cash provided by (used in) operating activities ...... 23,442 (42,256) (7,716)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment ............................... (11,281) (11,811) (4,824)
Proceeds from disposal of property and equipment .................. 123 91 48
Decrease in restricted cash ....................................... -- 14,372 15,115
Purchase of short-term investments ................................ (175,235) (178,355) (212,869)
Sale of short-term investments .................................... 170,404 216,182 170,939
--------- --------- ---------
Net cash provided by (used in) investing activities ...... (15,989) 40,479 (31,591)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock ............................ 596 1,712 50,397
Proceeds from debt borrowings ..................................... -- 34,000 --
Repayment of debt borrowings ...................................... (691) (52,713) --
Repayment of other long-term liabilities .......................... -- (2,466) --
--------- --------- ---------
Net cash provided by (used in) financing activities ...... (95) (19,467) 50,397
--------- --------- ---------
Net increase (decrease) in cash and cash equivalents ................. 7,358 (21,244) 11,090
Cash and cash equivalents at beginning of year ....................... 14,612 35,856 24,766
--------- --------- ---------
Cash and cash equivalents at end of year ............................. $ 21,970 $ 14,612 $ 35,856
========= ========= =========

SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid for interest ............................................ $ 2,783 $ 1,985 $ 4

SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING AND FINANCING
ACTIVITIES:
Unrealized loss on investments .................................... $ (52) $ -- $ --
Deferred stock compensation, net of reversals ..................... $ 39 $ 41 $ 92
Retirement of property and equipment .............................. $ 4,554 $ 963 $ 1,148
Property and equipment recorded in connection with
consolidation of variable interest entity ...................... $ -- $ -- $ 54,811
Long-term debt recorded in connection with consolidation of
variable interest entity ....................................... $ -- $ -- $ (52,344)
Other long-term liabilities recorded in connection with
consolidation of variable interest entity ...................... $ -- $ -- $ (2,467)
</TABLE>

The accompanying notes are an integral part of
these consolidated financial statements.


F-6
LEXICON GENETICS INCORPORATED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

DECEMBER 31, 2005

1. ORGANIZATION AND OPERATIONS

Lexicon Genetics Incorporated (Lexicon or the Company) is a Delaware corporation
incorporated on July 7, 1995. Lexicon was organized to discover the functions
and pharmaceutical utility of genes and use those gene function discoveries in
the discovery and development of pharmaceutical products for the treatment of
human disease.

Lexicon has financed its operations from inception primarily through sales of
common and preferred stock, payments received under collaboration and alliance
agreements, database subscription agreements, government grants and contracts,
technology licenses, and financing obtained under debt and lease arrangements.
The Company's future success is dependent upon many factors, including, but not
limited to, its ability to discover and develop pharmaceutical products for the
treatment of human disease, discover additional promising candidates for drug
discovery and development using its gene knockout technology, establish
additional collaboration and license agreements, achieve milestones under such
agreements, obtain and enforce patents and other proprietary rights in its
discoveries, comply with federal and state regulations, and maintain sufficient
capital to fund its activities. As a result of the aforementioned factors and
the related uncertainties, there can be no assurance of the Company's future
success.

2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Basis of Presentation: The accompanying consolidated financial statements
include the accounts of Lexicon and its subsidiaries. Intercompany transactions
and balances are eliminated in consolidation.

Use of Estimates: The preparation of financial statements in conformity with U.
S. generally accepted accounting principles requires management to make
estimates and assumptions that affect the reported amounts of assets and
liabilities and disclosure of contingent assets and liabilities at the date of
the financial statements and the reported amounts of revenues and expenses
during the period. Actual results could differ from those estimates.

Cash, Cash Equivalents and Short-term Investments: Lexicon considers all
highly-liquid investments with original maturities of three months or less to be
cash equivalents. Short-term investments consist of certificates of deposit,
U.S. government agency debt obligations, corporate debt securities and auction
rate securities. Short-term investments are classified as available-for-sale
securities and are carried at fair value, based on quoted market prices of the
securities. The Company views its available-for-sale securities as available for
use in current operations regardless of the stated maturity date of the
security. Unrealized gains and losses on such securities are reported as a
separate component of stockholders equity. Net realized gains and losses,
interest and dividends are included in interest income. The cost of securities
sold is based on the specific identification method.

Restricted Cash and Investments: Lexicon is required to maintain restricted cash
or investments to collateralize standby letters of credit for the lease on its
office and laboratory facilities in Hopewell, New Jersey (see Note 10). As of
December 31, 2005 and 2004, restricted cash and investments were $0.4 million.

Concentration of Credit Risk: Lexicon's cash equivalents, short-term investments
and accounts receivable represent potential concentrations of credit risk. The
Company minimizes potential concentrations of risk in cash equivalents and
short-term investments by placing investments in high-quality financial
instruments. The Company's accounts receivable are unsecured and are
concentrated in pharmaceutical and biotechnology companies located in the United
States, Europe and Japan. The Company has not experienced any significant credit
losses to date. In 2005, customers in the United States, Europe and Japan
represented 78%, 16% and 6% of revenue, respectively. In 2004, customers in the
United States, Japan and Europe represented 93%, 6% and 1% of revenue,
respectively. In 2003, customers in the United States, Europe and Japan
represented 89%, 10% and 1% of revenue, respectively. At December 31, 2005,
management believes that the Company has no significant concentrations of credit
risk.

Segment Information and Significant Customers: Lexicon operates in one business
segment, which primarily focuses on the discovery of the functions and
pharmaceutical utility of genes and the use of those gene function discoveries
in the discovery and development of pharmaceutical products for the treatment of
human disease. Substantially all of the Company's revenues have been derived
from drug discovery alliances, target validation


F-7
collaborations for the development and, in some cases, analysis of the
physiological effects of genes altered in knockout mice, technology licenses,
subscriptions to its databases, government grants and contracts and compound
library sales. In 2005, Bristol-Myers Squibb Company, Genentech, Inc. and N.V.
Organon represented 34%, 30% and 16% of revenues, respectively. In 2004,
Bristol-Myers Squibb, Genentech and Incyte Corporation represented 43%, 26% and
8% of revenues, respectively. In 2003, Incyte, Amgen Inc., Bristol-Myers Squibb
and Genentech represented 23%, 15%, 14% and 14% of revenues, respectively.

Property and Equipment: Property and equipment are carried at cost and
depreciated using the straight-line method over the estimated useful life of the
assets which ranges from three to 40 years. Maintenance, repairs and minor
replacements are charged to expense as incurred. Leasehold improvements are
amortized over the shorter of the estimated useful life or the remaining lease
term. Significant renewals and betterments are capitalized.

Impairment of Long-Lived Assets: Under Statement of Financial Accounting
Standards (SFAS) No. 144, "Accounting for the Impairment or Disposal of
Long-Lived Assets," long-lived assets and certain identifiable intangible assets
to be held and used are reviewed for impairment when events or changes in
circumstances indicate that the carrying amount of such assets may not be
recoverable. Determination of recoverability is based on an estimate of
undiscounted future cash flows resulting from the use of the asset and its
eventual disposition. In the event that such cash flows are not expected to be
sufficient to recover the carrying amount of the assets, the assets are written
down to their estimated fair values.

Goodwill Impairment: Under SFAS No. 142, "Goodwill and Other Intangible Assets,"
goodwill is not amortized, but is tested at least annually for impairment at the
reporting unit level. Impairment is the condition that exists when the carrying
amount of goodwill exceeds its implied fair value. The first step in the
impairment process is to determine the fair value of the reporting unit and then
compare it to the carrying value, including goodwill. If the fair value exceeds
the carrying value, no further action is required and no impairment loss is
recognized. Additional impairment assessments may be performed on an interim
basis if the Company encounters events or changes in circumstances that would
indicate that, more likely than not, the carrying value of goodwill has been
impaired. There was no impairment of goodwill in 2005.

Revenue Recognition: Revenues are recognized under Staff Accounting Bulletin
(SAB) No. 104, "Revenue Recognition," when persuasive evidence of an arrangement
exists, delivery has occurred or services have been rendered, the price is fixed
and determinable and collectibility is reasonably assured. Payments received in
advance under these arrangements are recorded as deferred revenue until earned.
Revenues are earned from drug discovery alliances, target validation
collaborations, database subscriptions, technology licenses, and government
grants and contracts.

Upfront fees under drug discovery alliances are recognized as revenue on a
straight-line basis over the estimated period of service, generally the
contractual research term, to the extent they are non-refundable. Research
funding under these alliances is recognized as services are performed to the
extent they are non-refundable, either on a straight-line basis over the
estimated service period, generally the contractual research term; or as
contract research costs are incurred. Milestone-based fees are recognized upon
completion of specified milestones according to contract terms. Fees for access
to databases and other target validation resources are recognized ratably over
the subscription or access period. Payments received under target validation
collaborations and government grants and contracts are recognized as revenue as
Lexicon performs its obligations related to such research to the extent such
fees are non-refundable. Non-refundable technology license fees are recognized
as revenue upon the grant of the license when performance is complete and there
is no continuing involvement.

Revenues recognized from multiple element contracts are allocated to each
element of the arrangement based on the relative fair values of the elements.
The determination of fair value of each element is based on objective evidence.
When revenues for an element are specifically tied to a separate earnings
process, revenue is recognized when the specific performance obligation
associated with the element is completed. When revenues for an element are not
specifically tied to a separate earnings process, they are recognized ratably
over the term of the agreement.

Research and Development Expenses: Research and development expenses consist of
costs incurred for company-sponsored as well as collaborative research and
development activities. These costs include direct and research-related overhead
expenses and are expensed as incurred. Patent costs and technology license fees
for technologies that are utilized in research and development and have no
alternative future use are expensed when incurred.


F-8
Stock-Based Compensation: As further discussed in Note 12, Lexicon has three
stock-based compensation plans, which are accounted for under the recognition
and measurement provisions of Accounting Principles Board (APB) Opinion No. 25,
"Accounting for Stock Issued to Employees, and Related Interpretations." Under
the intrinsic value method described in APB Opinion No. 25, no compensation
expense is recognized if the exercise price of the employee stock option equals
the market price of the underlying stock on the date of grant. Lexicon reversed
$21,000 of stock-based compensation expense during the year ended December 31,
2005 and recognized $0.8 million and $10.1 million during 2004 and 2003,
respectively, which was primarily related to option grants made prior to
Lexicon's April 2000 initial public offering. The following table illustrates
the effect on net loss and net loss per share if the fair value recognition
provisions of SFAS No. 123, "Accounting for Stock Based Compensation," had been
applied to all outstanding and unvested awards in each period:

<TABLE>
<CAPTION>
YEAR ENDED DECEMBER 31,
------------------------------
2005 2004 2003
-------- -------- --------
(IN THOUSANDS)
<S> <C> <C> <C>
Net loss, as reported ........................ $(36,315) $(47,172) $(64,198)
Add: Stock-based compensation expense included
in reported net loss ...................... (21) 838 10,115
Deduct: Total stock-based compensation expense
determined under fair value based method
for all awards ............................ (11,496) (16,189) (26,344)
-------- -------- --------
Pro forma net loss ........................... $(47,832) $(62,523) $(80,427)
======== ======== ========
Net loss per common share, basic and diluted
As reported ............................... $ (0.57) $ (0.74) $ (1.13)
======== ======== ========
Pro forma ................................. $ (0.75) $ (0.99) $ (1.42)
======== ======== ========
</TABLE>

Change in Accounting Principle: Lexicon adopted Financial Accounting Standards
Board Interpretation No. 46, "Consolidation of Variable Interest Entities - An
Interpretation of ARB No. 51," or FIN 46 on December 31, 2003. It requires that
unconsolidated variable interest entities be consolidated by their primary
beneficiaries. A primary beneficiary is the party that absorbs a majority of the
entity's expected losses or residual benefits. The Company determined that the
lessor under the synthetic lease, as described in Note 9, was a variable
interest entity as defined by FIN 46, and that Lexicon absorbed a majority of
the variable interest entity's expected losses. Accordingly, the Company
consolidated the assets of the variable interest entity, which were comprised of
property and improvements funded under the synthetic lease. These assets had a
carrying value of $54.8 million, net of accumulated depreciation of $3.1
million, on December 31, 2003. The Company also consolidated the variable
interest entity's debt of $52.3 million and non-controlling interests of $2.5
million, which amounts were included in long-term debt and other long-term
liabilities, respectively. Additionally, the Company recorded a cumulative
effect of a change in accounting principle equal to the accumulated depreciation
of $3.1 million for the period from the date the buildings were placed in
service under the synthetic lease through December 31, 2003. As discussed in
Note 9, in April 2004, Lexicon purchased the facilities subject to the synthetic
lease, repaying the amounts funded under the synthetic lease with proceeds from
a mortgage financing and cash.

Net Loss per Common Share: Net loss per common share is computed using the
weighted average number of shares of common stock outstanding. Shares associated
with stock options and warrants are not included because they are antidilutive.

Comprehensive Loss: Comprehensive loss is comprised of net loss and unrealized
gains and losses on available-for-sale securities. Comprehensive loss is
reflected in the consolidated statements of stockholders' equity. There were
$52,000 of unrealized losses as of December 31, 2005 and no unrealized gains or
losses as of December 31, 2004 and 2003.

3. RECENT ACCOUNTING PRONOUNCEMENT

In December 2004, the Financial Accounting Standards Board ("FASB") issued SFAS
123 (Revised), "Share-Based Payment." The statement eliminates the ability to
account for stock-based compensation using APB 25 and requires such transactions
be recognized as compensation expense in the income statement based on their
fair values on the date of the grant, with the compensation expense recognized
over the period in which an employee is required to provide service in exchange
for the stock award. The Company will adopt this statement on January 1, 2006
using a modified prospective application. As such, the compensation expense
recognition provisions will apply to new awards and to any awards modified,
repurchased or canceled after the adoption date. Additionally, for any unvested


F-9
awards outstanding at the adoption date, the Company will recognize compensation
expense over the remaining vesting period. The Company is currently evaluating
the impact of SFAS 123 (Revised) on its financial condition and results of
operations. However, using a Black-Scholes option pricing model consistent with
its current practice, the adoption of SFAS 123 (Revised) on January 1, 2006 is
estimated to result in additional compensation expense of approximately $7.0
million to $9.0 million for the year ended December 31, 2006. This estimate is
dependent upon market price, assumptions used in estimating the fair value of
stock options, and the level of stock option grants and cancellations in 2006.

4. RECLASSIFICATION

In the consolidated balance sheet as of December 31, 2003, Lexicon has
reclassified $46.1 million of auction rate securities from cash equivalents to
short-term investments and $42.6 million from restricted cash to short-term
investments. The accompanying consolidated statements of cash flow for the year
ended December 31, 2003 has been adjusted to reflect this reclassification.

5. CASH AND CASH EQUIVALENTS AND INVESTMENTS

The fair value of cash and cash equivalents and investments held at December 31,
2005 and 2004 are as follows:

<TABLE>
<CAPTION>
AS OF DECEMBER 31, 2005
----------------------------------------------------------------
AMORTIZED GROSS UNREALIZED GROSS UNREALIZED ESTIMATED FAIR
COST GAINS LOSSES VALUE
--------- ---------------- ---------------- --------------
(IN THOUSANDS)
<S> <C> <C> <C> <C>
Cash and cash equivalents ............................ $21,982 $-- $(12) $21,970
======= === ==== =======

Securities maturing within one year:
Certificates of deposit ........................... 574 -- -- 574
Corporate debt securities ......................... 18,941 -- (45) 18,896
------- --- ---- -------
Total securities maturing within one year....... 19,515 -- (45) 19,470
Securities maturing after ten years:
Auction rate securities ........................... 58,250 5 -- 58,255
------- --- ---- -------
Total available-for-sale investments ................. $77,765 $ 5 $(45) $77,725
======= === ==== =======

Total cash and cash equivalents and investments ...... $99,747 $ 5 $(57) $99,695
======= === ==== =======
</TABLE>

<TABLE>
<CAPTION>
AS OF DECEMBER 31, 2004
----------------------------------------------------------------
AMORTIZED GROSS UNREALIZED GROSS UNREALIZED ESTIMATED FAIR
COST GAINS LOSSES VALUE
--------- ---------------- ---------------- --------------
(IN THOUSANDS)
<S> <C> <C> <C> <C>
Cash and cash equivalents ............................ $14,612 $-- $-- $14,612
======= === === =======

Securities maturing within one year:
Certificates of deposit ........................... 565 -- -- 565
U.S. government agencies .......................... 2,499 -- -- 2,499
Corporate debt securities ......................... 25,832 -- -- 25,832
Auction rate securities ........................... 1,000 -- -- 1,000
------- --- --- -------
Total securities maturing within one year ...... 29,896 29,896
Securities maturing after one year through five years:
Auction rate securities ........................... 7,450 -- -- 7,450
Securities maturing after ten years:
Auction rate securities ........................... 35,600 -- -- 35,600
------- --- --- -------
Total available-for-sale investments ................. $72,946 $-- $-- $72,946
======= === === =======

Total cash and cash equivalents and investments ...... $87,558 $-- $-- $87,558
======= === === =======
</TABLE>

There were no realized gains or losses for the years ended December 31, 2005,
2004 and 2003.


F-10
6.   PROPERTY AND EQUIPMENT

Property and equipment at December 31, 2005 and 2004 are as follows:

<TABLE>
<CAPTION>
ESTIMATED AS OF DECEMBER 31,
USEFUL LIVES -------------------
IN YEARS 2005 2004
------------ -------- --------
(IN THOUSANDS)
<S> <C> <C> <C>
Computers and software ........................... 3-5 $ 12,768 $ 12,522
Furniture and fixtures ........................... 5-7 7,596 7,538
Laboratory equipment ............................. 3-7 36,306 33,764
Leasehold improvements ........................... 7-10 9,740 7,764
Buildings ........................................ 15-40 63,217 61,313
Land ............................................. -- 3,564 3,564
-------- --------
Total property and equipment .................. 133,191 126,465
Less: Accumulated depreciation and amortization .. (47,926) (41,892)
-------- --------
Net property and equipment .................... $ 85,265 $ 84,573
======== ========
</TABLE>

7. INCOME TAXES

Lexicon recognizes deferred tax liabilities and assets for the expected future
tax consequences of events that have been recognized differently in the
financial statements and tax returns. Under this method, deferred tax
liabilities and assets are determined based on the difference between the
financial statement carrying amounts and tax bases of liabilities and assets
using enacted tax rates and laws in effect in the years in which the differences
are expected to reverse. Deferred tax assets are evaluated for realization based
on a more-likely-than-not criteria in determining if a valuation allowance
should be provided.

The components of Lexicon's deferred tax assets (liabilities) at December 31,
2005 and 2004 are as follows:

<TABLE>
<CAPTION>
AS OF DECEMBER 31,
--------------------
2005 2004
--------- --------
(IN THOUSANDS)
<S> <C> <C>
Deferred tax assets:
Net operating loss carryforwards ...... $ 64,645 $ 66,767
Research and development tax credits .. 12,391 8,597
Stock-based compensation .............. 6,001 7,206
Deferred revenue ...................... 28,546 13,149
Other ................................. 724 2,121
--------- --------
Total deferred tax assets .......... 112,307 97,840

Deferred tax liabilities:
Property and equipment ................ (1,262) (1,502)
Other ................................. (346) (139)
--------- --------
Total deferred tax liabilities ..... (1,608) (1,641)
Less: Valuation allowance ................ (110,699) (96,199)
--------- --------
Net deferred tax assets ............ $ -- $ --
========= ========
</TABLE>

At December 31, 2005, Lexicon had net operating loss carryforwards of
approximately $184.7 million and research and development tax credit
carryforwards of approximately $12.4 million available to reduce future income
taxes. These carryforwards will begin to expire in 2011. A change in ownership,
as defined by federal income tax regulations, could significantly limit the
Company's ability to utilize its carryforwards. Based on the federal tax law
limits and the Company's cumulative loss position, Lexicon concluded it was
appropriate to establish a full valuation allowance for its net deferred tax
assets until an appropriate level of profitability is sustained. During 2005,
the valuation allowance increased $14.5 million primarily due to the Company's
current year net loss. Lexicon recorded a $119,000 income tax provision
representing current alternative minimum tax payable based on taxable income for
the year ended December 31, 2005.

8. GOODWILL AND OTHER INTANGIBLE ASSETS

On July 12, 2001, Lexicon completed the acquisition of Coelacanth Corporation in
a merger. Coelacanth, now Lexicon Pharmaceuticals (New Jersey), Inc., forms the
core of Lexicon Pharmaceuticals, the division of the


F-11
Company responsible for small molecule compound discovery. The results of
Lexicon Pharmaceuticals (New Jersey), Inc. are included in the Company's results
of operations for the period subsequent to the acquisition.

Goodwill associated with the acquisition of $25.8 million, which represents the
excess of the $36.0 million purchase price over the fair value of the underlying
net identifiable assets, was assigned to the consolidated entity, Lexicon. There
was no change in the carrying amount of goodwill for the year ended December 31,
2005. In accordance with SFAS No. 142, the goodwill balance is not subject to
amortization, but is tested at least annually for impairment at the reporting
unit level, which is the Company's single operating segment. The Company
performed an impairment test of goodwill on its annual impairment assessment
date. This test did not result in an impairment of goodwill.

Other intangible assets represent Coelacanth's technology platform, which
consists of its proprietary ClickChem(TM) reactions, novel building blocks and
compound sets, automated production systems, high-throughput ADMET (Absorption,
Distribution, Metabolism, Excretion and Toxicity) capabilities, and its know-how
and trade secrets. The Company amortizes other intangible assets on a
straight-line basis over an estimated life of five years.

The amortization expense for the year ended December 31, 2005 was $1.2 million.
The estimated remaining amortization expense is $0.6 million for the year ending
December 31, 2006.

9. DEBT OBLIGATIONS

Genentech Loan: On December 31, 2002, Lexicon borrowed $4.0 million under an
unsecured note agreement with Genentech, Inc. The proceeds of the loan were to
be used to fund research efforts under the alliance agreement with Genentech
discussed in Note 14. On November 30, 2005, the note agreement was amended to
extend the maturity date of the loan by one year to December 31, 2006. No other
terms of the note agreement were changed. The Company may repay the note, at any
time, at its option, in cash, in shares of common stock valued at the
then-current market price, or in a combination of cash and shares, subject to
certain limitations. The note accrues interest at an annual rate of 8%,
compounded quarterly. The $4.0 million note has been classified as a current
liability on the accompanying consolidated balance sheet as of December 31,
2005.

Mortgage Loan: In October 2000, Lexicon entered into a synthetic lease agreement
under which the lessor purchased the Company's existing laboratory and office
buildings and animal facility in The Woodlands, Texas and agreed to fund the
construction of additional facilities. Including the purchase price for the
Company's existing facilities, the synthetic lease, as amended, provided funding
of $54.8 million in property and improvements and required that the Company
maintain restricted cash or investments to collateralize these borrowings. In
April 2004, Lexicon purchased the facilities subject to the synthetic lease,
repaying the $54.8 million funded under the synthetic lease with proceeds from a
$34.0 million third-party mortgage financing and $20.8 million in cash. The
mortgage loan has a ten-year term with a 20-year amortization and bears interest
at a fixed rate of 8.23%. As a result of the refinancing, all restrictions on
the cash and investments that had secured the obligations under the synthetic
lease were eliminated. The buildings and land that serve as collateral for the
mortgage loan are included in property and equipment at $63.2 million and $3.6
million, respectively, before accumulated depreciation.

The following table includes the aggregate future principal payments of the
Company's long-term debt as of December 31, 2005:

<TABLE>
<CAPTION>
FOR THE YEAR
ENDING
DECEMBER 31
--------------
(IN THOUSANDS)
<S> <C>
2006..................... $ 4,751
2007..................... 816
2008..................... 880
2009..................... 964
2010..................... 1,047
Thereafter............... 28,482
-------
36,940
Less current portion..... (4,751)
-------
Total long-term debt.. $32,189
=======
</TABLE>

The fair value of Lexicon's debt financial instruments approximates their
carrying value. The fair value of Lexicon's long-term debt is estimated using
discounted cash flow analysis, based on the Company's estimated current
incremental borrowing rate.


F-12
10.  COMMITMENTS AND CONTINGENCIES

Operating Lease Obligations: A Lexicon subsidiary leases laboratory and office
space in Hopewell, New Jersey under an agreement that expires in June 2013. The
lease provides for two five-year renewal options at 95% of the fair market rent
and includes escalating lease payments. Rent expense is recognized on a
straight-line basis over the original lease term. Lexicon is the guarantor of
the obligation of its subsidiary under this lease. The Company is required to
maintain restricted investments to collateralize a standby letter of credit for
this lease. The Company had $0.4 million in restricted investments as collateral
as of December 31, 2005 and 2004. Additionally, Lexicon leases certain equipment
under operating leases.

Rent expense for all operating leases was approximately $2.4 million, $2.3
million and $3.7 million, for the years ended December 31, 2005, 2004 and 2003,
respectively. These amounts included rent expense related to the synthetic lease
in 2003. Payments under the synthetic lease made subsequent to the consolidation
of the lessor under the lease on December 31, 2003 are reflected in interest
expense rather than rent expense, as are the interest payments made under the
mortgage loan used to purchase the facilities funded under the synthetic lease
in April 2004. The following table includes non-cancelable, escalating future
lease payments for the facility in New Jersey:

<TABLE>
<CAPTION>
FOR THE YEAR
ENDING
DECEMBER 31
--------------
(IN THOUSANDS)
<S> <C>
2006........ $ 2,355
2007........ 2,355
2008........ 2,416
2009........ 2,476
2010........ 2,476
Thereafter.. 6,449
-------
Total ... $18,527
=======
</TABLE>

Employment Agreements: Lexicon has entered into employment agreements with
certain of its corporate officers. Under the agreements, each officer receives a
base salary, subject to adjustment, with an annual discretionary bonus based
upon specific objectives to be determined by the compensation committee. The
employment agreements are at-will and contain non-competition agreements. The
agreements also provide for a termination clause, which requires either a six or
12-month payment based on the officer's salary, in the event of termination or
change in corporate control.

11. CAPITAL STOCK

Common Stock: In July 2003, Lexicon completed the public offering and sale of
10.0 million shares of its common stock at a price of $5.25 per share. In August
2003, the underwriters partially exercised their over-allotment option,
purchasing an additional 240,000 shares. The total net proceeds from the
offering was $50.1 million, after deducting underwriting discounts of $3.2
million and offering expenses of $0.4 million.

12. STOCK OPTIONS AND WARRANTS

Stock Options

2000 Equity Incentive Plan: In September 1995, Lexicon adopted the 1995 Stock
Option Plan, which was subsequently amended and restated in February 2000 as the
2000 Equity Incentive Plan (the "Equity Incentive Plan"). The Equity Incentive
Plan will terminate in 2010 unless the Board of Directors terminates it sooner.
The Equity Incentive Plan provides that it will be administered by the Board of
Directors, or a committee appointed by the Board of Directors, which determines
recipients and types of options to be granted, including number of shares under
the option and the exercisability of the shares. The Equity Incentive Plan is
presently administered by the Compensation Committee of the Board of Directors.

The Equity Incentive Plan provides for the grant of incentive stock options to
employees and nonstatutory stock options to employees, directors and consultants
of the Company. The plan also permits the grant of stock bonuses and restricted
stock purchase awards. Incentive stock options have an exercise price of 100% or
more of the fair market value of our common stock on the date of grant.
Nonstatutory stock options may have an exercise price as low as 85% of fair
market value on the date of grant. The purchase price of other stock awards may
not be less than 85% of fair market value. However, the plan administrator may
award bonuses in consideration of past services


F-13
without a purchase payment. Shares may be subject to a repurchase option in the
discretion of the plan administrator.

The Board of Directors initially authorized and reserved an aggregate of
11,250,000 shares of common stock for issuance under the Equity Incentive Plan.
On January 1 of each year for ten years, beginning in 2001, the number of shares
reserved for issuance under the Equity Incentive Plan automatically will be
increased by the greater of:

- 5% of Lexicon's outstanding shares on a fully-diluted basis; or

- that number of shares that could be issued under awards granted under
the Equity Incentive Plan during the prior 12-month period;

provided that the Board of Directors may provide for a lesser increase in the
number of shares reserved under the Equity Incentive Plan for any year. The
total number of shares reserved in the aggregate may not exceed 30,000,000
shares over the ten-year period.

As of December 31, 2005, an aggregate of 18,000,000 shares of common stock had
been reserved for issuance, options to purchase 13,470,330 shares were
outstanding, and 3,517,804 shares had been issued upon the exercise of stock
options issued under the Equity Incentive Plan.

2000 Non-Employee Directors' Stock Option Plan: In February 2000, Lexicon
adopted the 2000 Non-Employee Directors' Stock Option Plan (the "Directors'
Plan") to provide for the automatic grant of options to purchase shares of
common stock to non-employee directors of the Company. Under the Directors'
Plan, non-employee directors first elected after the closing of the Company's
initial public offering receive an initial option to purchase 30,000 shares of
common stock. In addition, on the day following each of the Company's annual
meetings of stockholders, beginning with the annual meeting in 2001, each
non-employee director who has been a director for at least six months was
automatically granted an option to purchase 6,000 shares of common stock.
Beginning with the annual meeting in 2005, the annual grant was increased to an
option to purchase 10,000 shares of common stock. Initial option grants become
vested and exercisable over a period of five years and annual option grants
become vested over a period of 12 months from the date of grant. Options granted
under the Directors' Plan have an exercise price equal to the fair market value
of the Company's common stock on the date of grant and term of ten years from
the date of grant.

The Board of Directors initially authorized and reserved a total of 600,000
shares of its common stock for issuance under the Directors' Plan. On the day
following each annual meeting of Lexicon's stockholders, for 10 years, starting
in 2001, the share reserve will automatically be increased by a number of shares
equal to the greater of:

- 0.3% of the Company's outstanding shares on a fully-diluted basis; or

- that number of shares that could be issued under options granted under
the Directors' Plan during the prior 12-month period;

provided that the Board of Directors may provide for a lesser increase in the
number of shares reserved under the Directors' Plan for any year.

As of December 31, 2005, an aggregate of 600,000 shares of common stock had been
reserved for issuance, options to purchase 258,000 shares were outstanding, and
no options had been exercised under the Directors' Plan.

Coelacanth Corporation 1999 Stock Option Plan: Lexicon assumed the Coelacanth
Corporation 1999 Stock Option Plan (the "Coelacanth Plan") and the outstanding
stock options under the plan in connection with our July 2001 acquisition of
Coelacanth Corporation. The Company will not grant any further options under the
plan. As outstanding options under the plan expire or terminate, the number of
shares authorized for issuance under the plan will be correspondingly reduced.

The purpose of the plan was to provide an opportunity for employees, directors
and consultants of Coelacanth to acquire a proprietary interest, or otherwise
increase their proprietary interest, in Coelacanth as an incentive to continue
their employment or service. Both incentive and nonstatutory options are
outstanding under the plan. Most outstanding options vest over time and expire
ten years from the date of grant. The exercise price of options awarded under
the plan was determined by the plan administrator at the time of grant. In
general, incentive stock options have an exercise price of 100% or more of the
fair market value of Coelacanth common stock on the date of grant and
nonstatutory stock options have an exercise price as low as 85% of fair market
value on the date of grant.


F-14
As of December 31, 2005, an aggregate of 122,649 shares of common stock had been
reserved for issuance, options to purchase 74,051 shares of common stock were
outstanding, options to purchase 21,756 shares of common stock had been
canceled, and 26,842 shares of common stock had been issued upon the exercise of
stock options issued under the Coelacanth Plan.

Stock-Based Compensation: SFAS No. 123, "Accounting for Stock-Based
Compensation," allows companies to adopt one of two methods for accounting for
stock options. Lexicon has elected the method that requires disclosure only of
stock-based compensation. Because of this election, the Company is required to
account for its employee stock-based compensation plans under APB Opinion No. 25
and its related interpretations. Accordingly, deferred compensation is recorded
for stock-based compensation grants based on the excess of the estimated fair
value of the common stock on the measurement date over the exercise price. The
deferred compensation is amortized over the vesting period of each unit of
stock-based compensation grant, generally four years. If the exercise price of
the stock-based compensation grants is equal to the estimated fair value of the
Company's stock on the date of grant, no compensation expense is recorded.

During the year ended December 31, 2000, Lexicon recorded $54.1 million in
aggregate deferred compensation relating to options issued to employees and
non-employee directors prior to our initial public offering. The Company
recorded no stock-based compensation expense during the year ended December 31,
2005 and recognized $0.8 million and $10.1 million during the years ended
December 31, 2004 and 2003, respectively, which was primarily related to option
grants made prior to the Company's initial public offering.

The pro forma information regarding net loss required by SFAS No. 123 has been
included in Note 2. The information has been determined as if Lexicon had
accounted for its employee stock options under the fair-value method as defined
by SFAS No. 123. For purposes of pro forma disclosures, the estimated fair value
of the options is amortized to expense over the vesting period of the options
using the straight-line method. The fair value of these options was estimated at
the date of grant using the Black-Scholes method. The Black-Scholes
option-pricing model requires the input of subjective assumptions. Because the
Company's employee stock options have characteristics significantly different
from those of traded options, and because changes in the subjective input
assumptions can materially affect the fair value estimate, in management's
opinion, the existing models do not necessarily provide a reliable single
measure of the fair value of its employee stock options. The following
weighted-average assumptions were used for 2005, 2004 and 2003:

- volatility factors of 72%, 92%, and 92%, respectively;

- risk-free interest rates of 4.19%, 3.69%, and 3.40%, respectively;

- expected option lives of seven years;

- three percent expected turnover; and

- no dividends.

Lexicon records the fair value of options issued to non-employee consultants and
re-measures the fair value at each reporting date. The fair values of the
issuances were estimated using the Black-Scholes pricing model with the
assumptions noted in the preceding paragraph. Any expense is recognized over the
service period or at the date of issuance if the options are fully vested and no
performance obligation exists. Lexicon reversed stock-based compensation expense
of $21,000, recorded no expense and reversed $6,000 of expense during the years
ended December 31, 2005, 2004 and 2003, respectively.

Stock Option Activity: The following is a summary of option activity under
Lexicon's stock option plans:

<TABLE>
<CAPTION>
2005 2004 2003
------------------ ------------------ ------------------
WEIGHTED WEIGHTED WEIGHTED
AVERAGE AVERAGE AVERAGE
EXERCISE EXERCISE EXERCISE
OPTIONS PRICE OPTIONS PRICE OPTIONS PRICE
------- -------- ------- -------- ------- --------
(IN THOUSANDS, EXCEPT EXERCISE PRICE DATA)
<S> <C> <C> <C> <C> <C> <C>
Outstanding at beginning of year 13,299 $ 6.20 12,889 $ 6.12 11,372 $6.47
Granted 2,104 5.55 1,935 7.40 1,897 4.24
Exercised (1,063) 0.56 (664) 2.65 (102) 2.34
Canceled (538) 10.79 (861) 10.44 (278) 8.92
------ ------ ------
Outstanding at end of year 13,802 6.36 13,299 6.20 12,889 6.12
====== ====== ======
Exercisable at end of year 10,312 $ 6.50 9,908 $ 5.96 9,345 $5.73
====== ====== ======
</TABLE>

The weighted average fair values of options granted during the years ended
December 31, 2005, 2004 and 2003 were $3.93, $5.95, and $3.52, respectively. As
of December 31, 2005, 1,353,866 shares of common stock were available for grant
under Lexicon's stock option plans.


F-15
Stock Options Outstanding: The following table summarizes information about
stock options outstanding at December 31, 2005:

<TABLE>
<CAPTION>
OPTIONS OUTSTANDING OPTIONS EXERCISABLE
----------------------------------------------------- ----------------------------------
WEIGHTED AVERAGE
REMAINING WEIGHTED WEIGHTED
RANGE OF OUTSTANDING AS OF CONTRACTUAL AVERAGE EXERCISABLE AS OF AVERAGE
EXERCISE PRICE DECEMBER 31, 2005 LIFE (IN YEARS) EXERCISE PRICE DECEMBER 31, 2005 EXERCISE PRICE
-------------- ----------------- ---------------- -------------- ----------------- --------------
(IN THOUSANDS) (IN THOUSANDS)
<S> <C> <C> <C> <C> <C>
$ 1.67 - 2.50 4,777 3.3 $ 2.40 4,777 $ 2.40
3.16 - 4.72 1,548 7.5 4.00 962 3.95
4.76 - 7.12 2,567 8.7 5.81 477 5.91
7.15 - 10.55 3,043 6.9 8.55 2,230 8.85
10.87 - 16.00 1,373 5.3 12.62 1,372 12.62
16.63 - 22.06 364 4.3 19.71 364 19.71
25.25 - 31.63 28 4.8 26.23 28 26.23
38.00 - 38.50 102 4.7 38.49 102 38.49
------ ------
13,802 $ 6.36 10,312 $ 6.50
====== ======
</TABLE>

Warrants

In July 1998, Lexicon issued a warrant to purchase 249,999 shares of common
stock at an exercise price of $2.50 per share, in connection with the grant to
the Company of an option to lease additional real property. Amortization of the
remaining balance of $155,000 on the lease option was expensed in 2000 upon the
Company's completion of a synthetic lease agreement under which the lessor
purchased the optioned real property under an arrangement providing for its
lease to the Company. The warrant was exercised in 2003 by way of a cashless
exercise, resulting in the issuance of a total of 117,784 shares of common
stock.

In connection with the acquisition of Coelacanth in July 2001, Lexicon assumed
Coelacanth's outstanding warrants to purchase 25,169 shares of common stock. The
warrants expire on March 31, 2009. The fair value of the warrants was included
in the total purchase price for the acquisition. As of December 31, 2005,
warrants to purchase 16,483 shares of common stock, with an exercise price of
$11.93 per share, remained outstanding.

Aggregate Shares Reserved for Issuance

As of December 31, 2005 an aggregate of 13,818,864 shares of common stock were
reserved for issuance upon exercise of outstanding stock options and warrants
and 1,353,866 additional shares were available for future grants under Lexicon's
stock option plans.

13. BENEFIT PLANS

Lexicon has established an Annual Profit Sharing Incentive Plan (the Profit
Sharing Plan). The purpose of the Profit Sharing Plan is to provide for the
payment of incentive compensation out of the profits of the Company to certain
of its employees. Participants in the Profit Sharing Plan are entitled to an
annual cash bonus equal to their proportionate share (based on salary) of 15
percent of the Company's annual pretax income, if any.

Lexicon maintains a defined-contribution savings plan under Section 401(k) of
the Internal Revenue Code. The plan covers substantially all full-time
employees. Participating employees may defer a portion of their pretax earnings,
up to the Internal Revenue Service annual contribution limit. Beginning in 2000,
the Company was required to match employee contributions according to a
specified formula. The matching contributions totaled approximately $821,000,
$776,000, and $637,000, in 2005, 2004 and 2003, respectively. Company
contributions are vested based on the employee's years of service, with full
vesting after four years of service.

14. COLLABORATION AND LICENSE AGREEMENTS

Lexicon has derived substantially all of its revenues from drug discovery
alliances, target validation collaborations for the development and, in some
cases, analysis of the physiological effects of genes altered in knockout mice,
government grants and contracts, technology licenses, subscriptions to its
databases and compound library sales.


F-16
Drug Discovery Alliances

Lexicon has entered into the following alliances for the discovery and
development of therapeutics based on its in vivo drug target discovery efforts:

Bristol-Myers Squibb Company: Lexicon established an alliance with Bristol-Myers
Squibb in December 2003 to discover, develop and commercialize small molecule
drugs in the neuroscience field. Lexicon initiated the alliance with a number of
drug discovery programs at various stages of development and is continuing to
use its gene knockout technology to identify additional drug targets with
promise in the neuroscience field. For those targets that are selected for the
alliance, Lexicon and Bristol-Myers Squibb are working together, on an exclusive
basis, to identify, characterize and carry out the preclinical development of
small molecule drugs, and will share equally both in the costs and in the work
attributable to those efforts. As drugs resulting from the collaboration enter
clinical trials, Bristol-Myers Squibb will have the first option to assume full
responsibility for clinical development and commercialization.

Lexicon received an upfront payment of $36.0 million and is entitled to receive
research funding of $30.0 million in the initial three years of the agreement.
Bristol-Myers Squibb has the option to extend the discovery portion of the
alliance for an additional two years in exchange for further committed research
funding of up to $50.0 million. Lexicon may receive additional cash payments for
exceeding specified research productivity levels. Lexicon will also receive
clinical and regulatory milestone payments for each drug target for which
Bristol-Myers Squibb develops a drug under the alliance. Lexicon will earn
royalties on sales of drugs commercialized by Bristol-Myers Squibb. The party
with responsibility for the clinical development and commercialization of drugs
resulting from the alliance will bear the costs of those efforts. Revenue
recognized under this agreement was $21.8 million, $21.5 million and $0.8
million for the years ended December 31, 2005, 2004 and 2003, respectively.

Genentech, Inc. Lexicon established an alliance with Genentech in December 2002
to discover novel therapeutic proteins and antibody targets. Under the original
alliance agreement, Lexicon used its target validation technologies to discover
the functions of secreted proteins and potential antibody targets identified
through Genentech's internal drug discovery research. Lexicon received an
upfront payment of $9.0 million and funding under a $4.0 million loan in 2002.
The terms of the loan are discussed in Note 9. In addition, Lexicon received
$24.0 million in performance payments for its work in the collaboration as it
was completed.

In November 2005, Lexicon and Genentech expanded the alliance to include the
advanced research, development and commercialization of new biotherapeutic
drugs. Lexicon will receive a total of $25.0 million in upfront and milestone
payments and research funding for the three-year advanced research portion of
the expanded alliance. In the expanded alliance, Lexicon is conducting advanced
research on a broad subset of targets validated in the original collaboration
using Lexicon's proprietary gene knockout technology.

Lexicon may develop and commercialize drugs for up to six of the targets
included in the alliance. Genentech retains an option on the potential
development and commercialization of these drugs under a cost and profit sharing
arrangement, with Lexicon having certain conditional rights to co-promote drugs
on a worldwide basis. Genentech is entitled to receive milestone payments in the
event of regulatory approval and royalties on net sales of products
commercialized by Lexicon outside of a cost and profit sharing arrangement.
Lexicon will receive payments from Genentech upon achievement of milestones
related to the development and regulatory approval of certain drugs resulting
from the alliance that are developed and commercialized by Genentech. Lexicon is
also entitled to receive royalties on net sales of these products, provided they
are not included in a cost and profit sharing arrangement. Lexicon retains
non-exclusive rights for the development and commercialization of small molecule
drugs addressing the targets included in the alliance.

Revenue recognized under this agreement was $22.6 million, $16.0 million and
$6.0 million for the years ended December 31, 2005, 2004 and 2003, respectively

Incyte Corporation. Lexicon established an alliance with Incyte in June 2001 to
discover novel therapeutic proteins using the Company's target validation
technologies in the discovery of the functions of secreted proteins from
Incyte's LifeSeq(R) Gold database. Under the alliance agreement, the Company and
Incyte each had the right to obtain exclusive commercialization rights,
including sublicensing rights, for an equal number of qualifying therapeutic
proteins, and will each receive milestone payments and royalties on sales of
therapeutic proteins from the alliance that are commercialized by the other
party or a third party sublicensee. Lexicon received research funding of $15.0
million under the agreement and recognized revenue of $2.5 million and $5.0
million for the years


F-17
ended December 31, 2004 and 2003, respectively. The collaboration period under
the agreement ended in June 2004.

N.V. Organon. Lexicon established an alliance with Organon in May 2005 to
jointly discover, develop and commercialize novel biotherapeutic drugs. In the
alliance, Lexicon is creating and analyzing knockout mice for up to 300 genes
selected by the parties that encode secreted proteins or potential antibody
targets, including two of Lexicon's existing drug discovery programs. The
parties will jointly select targets for further research and development and
will equally share costs and responsibility for research, preclinical and
clinical activities. The parties will jointly determine the manner in which
alliance products will be commercialized and will equally benefit from product
revenue. If fewer than five development candidates are designated under the
alliance, Lexicon's share of costs and product revenue will be proportionally
reduced. Lexicon will receive a milestone payment for each development candidate
in excess of five. Either party may decline to participate in further research
or development efforts with respect to an alliance product, in which case such
party will receive royalty payments on sales of such alliance product rather
than sharing in revenue. Organon will have principal responsibility for
manufacturing biotherapeutic products resulting from the alliance for use in
clinical trials and for worldwide sales.

Lexicon received an upfront payment of $22.5 million from Organon in exchange
for access to Lexicon's drug target discovery capabilities and the exclusive
right to co-develop biotherapeutic drugs for the 300 genes selected for the
alliance. This upfront payment will be recognized as revenue over the four-year
target function discovery portion of the alliance. Organon will also provide
Lexicon with annual research funding totaling up to $50.0 million for its 50%
share of the alliance's costs during this same period. Revenue recognized under
this agreement was $11.8 million for the year ended December 31, 2005.

Takeda Pharmaceutical Company Limited. Lexicon established an alliance with
Takeda in July 2004 to discover new drugs for the treatment of high blood
pressure. In the collaboration, Lexicon is using its gene knockout technology to
identify drug targets that control blood pressure. Takeda will be responsible
for the screening, medicinal chemistry, preclinical and clinical development and
commercialization of drugs directed against targets selected for the alliance,
and will bear all related costs. Lexicon received an upfront payment of $12.0
million from Takeda for the initial, three-year term of the agreement. This
upfront payment will be recognized as revenue over the three-year contractual
service period. Takeda has the option to extend the discovery portion of the
alliance for an additional two years in exchange for further committed funding.
Takeda will make research milestone payments to Lexicon for each target selected
for therapeutic development. In addition, Takeda will make clinical development
and product launch milestone payments to Lexicon for each product commercialized
from the collaboration. Lexicon will also earn royalties on sales of drugs
commercialized by Takeda. Revenue recognized under this agreement was $4.0
million and $3.2 million for the years ended December 31, 2005 and 2004,
respectively.

Other Collaborations and Arrangements

Lexicon has entered into the following other collaborations and arrangements:

Bristol-Myers Squibb Company. Lexicon established a LexVision collaboration with
Bristol-Myers Squibb in September 2000, under which Bristol-Myers Squibb was
granted non-exclusive access to the Company's LexVision database and OmniBank
library for the discovery of small molecule drugs. The Company received annual
access fees under this agreement, and is entitled to receive milestone payments
and royalties on products Bristol-Myers Squibb develops using the Company's
technology. The collaboration period under the agreement, as amended, expired in
December 2004. Revenue recognized under this agreement was $5.0 million in each
of the years ended December 31, 2004 and 2003.

Lexicon entered into a drug target validation agreement with Bristol-Myers
Squibb in December 2004. Under this agreement, Lexicon will develop mice and
phenotypic data for certain genes previously requested by Bristol-Myers Squibb
under its LexVision agreement, but that Lexicon was not required to deliver
thereunder, and certain additional genes requested by Bristol-Myers Squibb. The
agreement terminates in March 2007. The Company received payments totaling $5.0
million under the agreement. Revenue recognized under this agreement was $3.5
million for the year ended December 31, 2005.

Incyte Corporation. Lexicon established a LexVision collaboration with Incyte in
June 2001, under which Incyte was granted non-exclusive access to the Company's
LexVision database and OmniBank library for the discovery of small molecule
drugs. The Company received annual access fees under this agreement, and is
entitled to receive milestone payments and royalties on products Incyte develops
using the Company's technology. The collaboration


F-18
period under the agreement terminated in June 2004. Revenue recognized under
this agreement was $2.5 million and $5.0 million for the years ended December
31, 2004 and 2003, respectively.

Texas Institute for Genomic Medicine. In July 2005, Lexicon was awarded $35.0
million from the Texas Enterprise Fund for the creation of a knockout mouse
embryonic stem cell library containing 350,000 cell lines using Lexicon's
proprietary gene trapping technology. Lexicon is creating the library for the
Texas Institute for Genomic Medicine (TIGM), a newly formed non-profit institute
whose founding members are Texas A&M University, the Texas A&M University System
Health Science Center and Lexicon. TIGM researchers may also access specific
cells from Lexicon's current gene trap library of 270,000 mouse embryonic stem
cell lines and will have certain rights to utilize Lexicon's patented gene
targeting technologies. In addition, Lexicon will equip TIGM with the
bioinformatics software required for the management and analysis of data
relating to the library. The Texas Enterprise Fund has also awarded $15.0
million to the Texas A&M University System for the creation of facilities and
infrastructure to house the library. Revenue recognized under this agreement was
$3.1 million for the year ended December 31, 2005.

Under the terms of the award, Lexicon is responsible for the creation of a
specified number of jobs beginning in 2006, reaching an aggregate of 1,616 new
jobs in Texas by December 31, 2015. Lexicon will obtain credits based on funding
received by TIGM and certain related parties from sources other than the State
of Texas that it may offset against its potential liability for any job creation
shortfalls. Lexicon will also obtain credits against future jobs commitment
liabilities for any surplus jobs it creates. Subject to these credits, if
Lexicon fails to create the specified number of jobs, the state may require
Lexicon to repay $2,415 for each job Lexicon falls short. Lexicon's maximum
aggregate exposure for such payments, if Lexicon fails to create any new jobs,
is approximately $14.4 million, without giving effect to any credits to which
Lexicon may be entitled. The Texas A&M University System, together with TIGM,
has independent job creation obligations and is obligated for an additional
period to maintain an aggregate of 5,000 jobs, inclusive of those Lexicon
creates.

15. SELECTED QUARTERLY FINANCIAL DATA

The table below sets forth certain unaudited statements of operations data, and
net income (loss) per common share data, for each quarter of 2005 and 2004.

<TABLE>
<CAPTION>
QUARTER ENDED
------------------------------------------------
MARCH 31 JUNE 30 SEPTEMBER 30 DECEMBER 31
-------- -------- ------------ -----------
(UNAUDITED)
(IN THOUSANDS, EXCEPT PER SHARE DATA)
<S> <C> <C> <C> <C>
2005
Revenues .............................................................. $ 13,925 $ 13,898 $ 13,963 $33,894
Income (loss) from operations ......................................... $(13,267) $(14,519) $(14,055) $ 5,722
Net income (loss) ..................................................... $(13,266) $(14,842) $(14,121) $ 5,914
Net income (loss) per common share, basic and diluted ................. $ (0.21) $ (0.23) $ (0.22) $ 0.09
Shares used in computing net income (loss) per common share, basic .... 63,525 63,636 64,134 64,539
Shares used in computing net income (loss) per common share, diluted .. 63,525 63,636 64,134 67,317

2004
Revenues .............................................................. $ 11,842 $ 10,778 $ 13,109 $26,011
Loss from operations .................................................. $(15,603) $(16,444) $(13,949) $(1,458)
Net loss .............................................................. $(15,466) $(16,788) $(14,377) $ (541)
Net income (loss) per common share, basic and diluted ................. $ (0.25) $ (0.26) $ (0.23) $ (0.01)
Shares used in computing net loss per common share .................... 63,065 63,369 63,422 63,449
</TABLE>


F-19
Index to Exhibits

<TABLE>
<CAPTION>
EXHIBIT NO. DESCRIPTION
- ----------- -----------
<S> <C>
3.1 -- Restated Certificate of Incorporation (filed as Exhibit 3.1
to the Company's Registration Statement on Form S-1
(Registration No. 333-96469) and incorporated by reference
herein).

3.2 -- Restated Bylaws (filed as Exhibit 3.2 to the Company's
Registration Statement on Form S-1 (Registration No.
333-96469) and incorporated by reference herein).

*10.1 -- Restated Employment Agreement with Arthur T. Sands, M.D.,
Ph.D.

10.2 -- Employment Agreement with James R. Piggott, Ph.D. (filed as
Exhibit 10.2 to the Company's Registration Statement on Form
S-1 (Registration No. 333-96469) and incorporated by
reference herein).

10.3 -- Employment Agreement with Jeffrey L. Wade, J.D. (filed as
Exhibit 10.3 to the Company's Registration Statement on Form
S-1 (Registration No. 333-96469) and incorporated by
reference herein).

10.4 -- Employment Agreement with Brian P. Zambrowicz, Ph.D. (filed
as Exhibit 10.4 to the Company's Registration Statement on
Form S-1 (Registration No. 333-96469) and incorporated by
reference herein).

10.5 -- Employment Agreement with Julia P. Gregory (filed as Exhibit
10.5 to the Company's Registration Statement on Form S-1
(Registration No. 333-96469) and incorporated by reference
herein).

10.6 -- Employment Agreement with Alan Main, Ph.D. (filed as Exhibit
10.1 to the Company's Quarterly Report on Form 10-Q for the
period ended September 30, 2001 and incorporated by reference
herein).

10.7 -- Consulting Agreement with Alan S. Nies, M.D. dated February
19, 2003, as amended (filed as Exhibit 10.1 to the Company's
Quarterly Report on Form 10-Q for the period ended March 31,
2004 and incorporated by reference herein).

10.8 -- Consulting Agreement with Robert J. Lefkowitz, M.D. dated
March 31, 2003 (filed as Exhibit 10.1 to the Company's
Quarterly Report on Form 10-Q for the period ended March 31,
2003 and incorporated by reference herein).
</TABLE>
<TABLE>
<CAPTION>
EXHIBIT NO. DESCRIPTION
- ----------- -----------
<S> <C>
10.9 -- Consulting Agreement with C. Thomas Caskey, M.D. dated March
28, 2005 (filed as Exhibit 10.1 to the Company's Quarterly
Report on Form 10-Q for the period ended March 31, 2005 and
incorporated by reference herein).

10.10 -- Form of Indemnification Agreement with Officers and Directors
(filed as Exhibit 10.7 to the Company's Registration
Statement on Form S-1 (Registration No. 333-96469) and
incorporated by reference herein).

*10.11 -- Summary of Non-Employee Director Compensation.

*10.12 -- Summary of 2006 Named Executive Officer Cash Compensation.

10.13 -- 2000 Equity Incentive Plan (filed as Exhibit 10.10 to the
Company's Annual Report on Form 10-K for the period ended
December 31, 2004 and incorporated by reference herein).

*10.14 -- 2000 Non-Employee Directors' Stock Option Plan.

10.15 -- Coelacanth Corporation 1999 Stock Option Plan (filed as
Exhibit 99.1 to the Company's Registration Statement on Form
S-8 (Registration No. 333-66380) and incorporated by
reference herein).

10.16 -- Form of Stock Option Agreement with Officers under the 2000
Equity Incentive Plan (filed as Exhibit 10.2 to the Company's
Quarterly Report on Form 10-Q for the period ended September
30, 2004 and incorporated by reference herein).

*10.17 -- Form of Stock Option Agreement with Chairman of Board of
Directors under the 2000 Equity Incentive Plan.

10.18 -- Form of Stock Option Agreement with Directors under the 2000
Non-Employee Directors' Stock Option Plan (filed as Exhibit
10.3 to the Company's Quarterly Report on Form 10-Q for the
period ended September 30, 2004 and incorporated by reference
herein).

+10.19 -- Collaboration and License Agreement, dated December 17, 2003,
with Bristol-Myers Squibb Company (filed as Exhibit 10.15 to
the amendment to the Company's Annual Report on Form 10-K/A
for the period ended December 31, 2003, as filed on July 16,
2004, and incorporated by reference herein).

+10.20 -- Collaboration Agreement, dated July 27, 2004, with Takeda
Pharmaceutical Company Limited (filed as Exhibit 10.1 to the
Company's Quarterly Report on Form 10-Q for the period ended
September 30, 2004 and incorporated by reference herein).

+10.21 -- Collaboration and License Agreement, dated May 16, 2005, with
N.V. Organon and (only with respect to Section 9.4 thereof)
Intervet Inc. (filed as Exhibit 10.1 to the Company's
Quarterly Report on Form 10-Q for the period ended June 30,
2005 and incorporated by reference herein).

*+10.22 -- Second Amended and Restated Collaboration and License
Agreement, dated November 30, 2005, with Genentech, Inc.

10.23 -- Economic Development Agreement dated July 15, 2005, with the
State of Texas and the Texas A&M University System (filed as
Exhibit 10.1 to the Company's Quarterly Report on Form 10-Q
for the period ended September 30, 2005 and incorporated by
reference herein).

+10.24 -- Collaboration and License Agreement, dated July 15, 2005,
with the Texas A&M University System and the Texas Institute
for Genomic Medicine (filed as Exhibit 10.2 to the Company's
Quarterly Report on Form 10-Q for the period ended September
30, 2005 and incorporated by reference herein).

10.25 -- Loan and Security Agreement, dated April 21, 2004, between
Lex-Gen Woodlands, L.P. and iStar Financial Inc. (filed as
Exhibit 10.18 to the Company's Annual Report
</TABLE>
<TABLE>
<CAPTION>
EXHIBIT NO. DESCRIPTION
- ----------- -----------
<S> <C>
on Form 10-K for the period ended December 31, 2004 and
incorporated by reference herein).

10.26 -- Lease Agreement, dated May 23, 2002, between Lexicon
Pharmaceuticals (New Jersey), Inc. and Townsend Property
Trust Limited Partnership (filed as Exhibit 10.2 to the
Company's Quarterly Report on Form 10-Q for the period ended
June 30, 2002 and incorporated by reference herein).

21.1 -- Subsidiaries (filed as Exhibit 21.1 to the Company's Annual
Report on Form 10-K for the year ended December 31, 2004 and
incorporated by reference herein).

*23.1 -- Consent of Independent Registered Public Accounting Firm

*24.1 -- Power of Attorney (contained in signature page)

*31.1 -- Certification of CEO Pursuant to Section 302 of the
Sarbanes-Oxley Act of 2002

*31.2 -- Certification of CFO Pursuant to Section 302 of the
Sarbanes-Oxley Act of 2002

*32.1 -- Certification of CEO and CFO Pursuant to Section 906 of the
Sarbanes-Oxley Act of 2002
</TABLE>

- ----------
* Filed herewith.

+ Confidential treatment has been requested for a portion of this exhibit.
The confidential portions of this exhibit have been omitted and filed
separately with the Securities and Exchange Commission.