Page 1

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 ( Mark One ) 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 to FORM 10 - K Delaware ( State or other jurisdiction of incorporation or organization ) Title of Each Class Common Stock , par value $ 0.0001 per share Large accelerated filer Non - accelerated filer Emerging growth company Commission File No. 001-38800 Harpoon Therapeutics , Inc. ( Exact name of registrant as specified in its charter ) 47-3458693 ( I.R.S. Employer Identification Number ) 131 Oyster Point Blvd , Suite 300 South San Francisco , CA 94080 ( Address of principal executive offices ) Registrant's telephone number , including area code : ( 650 ) 443-7400 SECURITIES REGISTERED PURSUANT TO SECTION 12 ( b ) OF THE ACT : Name of Each Exchange On Which Registered NASDAQ Global Select Market Trading Symbol ( s ) HARP SECURITIES REGISTERED PURSUANT TO SECTION 12 ( g ) OF THE ACT : NONE Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . Yes 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 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 No 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 definitions of “ large accelerated filer , ” “ accelerated filer , ” “ smaller reporting company , ” and “ emerging growth company " in Rule 12b - 2 of the Exchange Act . Accelerated filer Smaller reporting 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 . 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 . Yes No Indicate by check mark whether the Registrant is a shell company ( as defined in Rule 12b - 2 of the Exchange Act ) . YES NO The aggregate market value of the voting and non - voting common equity held by non - affiliates of the Registrant , based on the closing price of the shares of common stock on The Nasdaq Stock Market on June 30 , 2020 , was $ 141,576,271 . The number of outstanding shares of the Registrant's common stock , par value $ 0.0001 , as of February 28 , 2021 was 32,408,849 . DOCUMENTS INCORPORATED BY REFERENCE Portions of the definitive proxy statement , or the Proxy Statement , for the 2021 Annual Meeting of Stockholders of the registrant are incorporated by reference into Part III of this Annual Report on Form 10 - K . The Proxy Statement will be filed with the Securities and Exchange Commission within 120 days of the registrant's fiscal year ended December 31 , 2020