A Failure to deliver also known as fails-to-deliver or FTD occurs when a buyer or seller is unable to meet his trading obligations.
FTDs for US listed companies are reported to the SEC and published twice a month.
Therefore there is a certain delay between the reporting and the publishing of the data.
Failures to deliver for Chimerix (CMRX) - 3 month history
Number of shares, 3 month chart
Biweekly Failures to deliver volume for Chimerix (CMRX) - since 2014
Volume in USD (price x number of shares), data since 2014
Chimerix (CMRX) Failure to deliver volume, Year over Year