Page 1

( Mark One ) ☑ ☐ 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 FOR THE TRANSITION PERIOD FROM ΤΟ Delaware Commission File Number 000-55939 Compass Therapeutics , Inc. ( Exact name of Registrant as specified in its Charter ) ( State or other jurisdiction of incorporation or organization ) 82-4876496 ( I.R.S. Employer Identification No. ) 80 Guest Street , Suite 601 Boston , Massachusetts ( Address of principal executive offices ) 02135 ( Zip Code ) Registrant's telephone number , including area code : ( 617 ) 500-8099 Securities registered pursuant to Section 12 ( b ) of the Act : Title of each class Common Stock , $ 0.0001 par value per share Securities registered pursuant to Section 12 ( g ) of the Act : None Trading Symbol ( s ) CMPX Name of each exchange on which registered OTCQB Stock Market 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 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 , 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 Non - accelerated filer 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 to Section 13 ( a ) of the Exchange Act . 凶 ☑ 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 registrant was not publicly traded as of the last business day of its most recently completed second fiscal quarter ( June 30 , 2020 ) , and thus information related to the aggregate market value of the registrant's voting and non - voting common stock held by non - affiliates of the registrant cannot be provided . On March 4 , 2021 , shares of the registrant's common stock were cleared for trading on the OTCQB Venture Market in the United States under the symbol CMPX . The number of shares of Registrant's Common Stock outstanding as of February 25 , 2021 was 52,112,143 . DOCUMENTS INCORPORATED BY REFERENCE The registrant intends to file a definitive proxy statement pursuant to Regulation 14A relating to the 2021 Annual Meeting of Stockholders within 120 days of the end of the registrant's fiscal year ended December 31 , 2020. Portions of such definitive proxy statement are incorporated by reference into Part III of this Annual Report on Form 10 - K to the extent stated herein .