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( Mark One ) X UNITED STATES SECURITIES AND EXCHANGE COMMISSION 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 Title of each class Common Stock Delaware ( State or other jurisdiction of incorporation or organization ) WASHINGTON , D.C. 20549 FORM 10 - K Commission File Number : 001-35798 HUMANIGEN , INC . ( Exact name of registrant as specified in its charter ) 533 Airport Boulevard , Ste . 400 Burlingame , CA 94005 ( Address of Principal Executive Offices ) ( Zip Code ) ( 650 ) 243-3100 ( Registrant's Telephone Number , Including Area Code ) Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) . Accelerated filer " HGEN 77-0557236 ( I.R.S. Employer Identification No. ) 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 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¨ Name of each exchange on which registered The Nasdaq Stock Market LLC 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 x No Non - accelerated filer > No x 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 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 ¨ Smaller reporting company Emerging growth company " X 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 x Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Act ) . Yes ¨ No x The aggregate market value of the registrant's voting stock held by non - affiliates as of June 30 , 2020 , was approximately $ 370,406,889 based on the closing price of $ 24.55 of the Common Stock of the registrant as reported on the OTCQB Venture Market operated by OTC Markets