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UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 10 - K ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31 , 2020 OR TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 Delaware ( State or other jurisdiction of incorporation or organization ) 1220 Concord Avenue , Suite 600 , Concord , California ( Address of principal executive offices ) For the transition period from Commission file number 000-21937 CERUS CORPORATION ( Exact name of registrant as specified in its charter ) Title of Each Class Common Stock , par value $ 0.001 per share to ( 925 ) 288-6000 ( Registrant's telephone number , including area code ) Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol CERS Securities registered pursuant to Section 12 ( g ) of the Act : Preferred Share Purchase Rights ( Title of Class ) 68-0262011 ( I.R.S. Employer Identification No. ) 94520 ( Zip Code ) Name of Each Exchange on Which Registered The Nasdaq Stock Market LLC Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . Yes > No Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15 ( d ) of the Act . Yes No > Indicate by check mark whether the registrant : ( 1 ) has filed all reports required to be filed by Section 13 or 15 ( d ) of the Securities Exchange Act of 1934 during the preceding 12 months ( or for such shorter period that the registrant was required to file such reports ) , and ( 2 ) has been subject to such filing requirements for the past 90 days . Yes > No Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S - T ( §232.405 of this chapter ) during the preceding 12 months ( or for such shorter period that the registrant was required to submit such files ) . Yes > No Indicate by check mark whether the registrant is a large accelerated filer , an accelerated filer , a non - accelerated filer , a smaller reporting company , or an emerging growth company . See the definitions of " large accelerated filer , " " accelerated filer , " “ smaller reporting company , " and " emerging growth company " in Rule 12b - 2 of the Exchange Act . Large accelerated filer > Accelerated filer Non - accelerated filer Smaller reporting company Emerging growth company If an emerging growth company , indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant Section 13 ( a ) of the Exchange Act . Indicate by check mark whether the registrant has filed a report on and attestation to its management's assessment of the effectiveness of its internal control over financial reporting under Section 404 ( b ) of the Sarbanes - Oxley Act ( 15 U.S.C. 7262 ( b ) ) by the registered public accounting firm that prepared or issued its audit report . Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Exchange Act ) . Yes No The approximate aggregate market value of the voting and non - voting common equity held by non - affiliates of the registrant as of June 30 , 2020 , the last business day of the registrant's most recently completed second fiscal quarter , based upon the closing sale price of the registrant's common stock listed on the Nasdaq Global Market , was $ 928 million . ( 1 ) As of February 10 , 2021 , there were 168,220,090 shares of the registrant's common stock outstanding . DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant's definitive proxy statement in connection with the registrant's 2021 Annual Meeting of Stockholders , to be filed with the Securities and Exchange Commission pursuant to Regulation 14A not later than 120 days after the end of the fiscal year ended December 31 , 2020 incorporated by reference into Part III of this Annual Report on Form 10 - K . ( 1 ) Based on a closing sale price of $ 6.60 per share on June 30 , 2020. Excludes 3.6 million shares of the registrant's common stock held by executive officers , directors and stockholders that the registrant has concluded were affiliates at June 30 , 2020 .