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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 FOR THE TRANSITION PERIOD FROM ΤΟ ALPINE IMMUNE SCIENCES , INC . ( Exact name of Registrant as specified in its Charter ) Delaware ( State or other jurisdiction of incorporation or organization ) 188 East Blaine Street Suite 200 Seattle , WA ( Address of principal executive offices ) None . Securities registered pursuant to Section 12 ( b ) of the Act : Commission File Number 001-37449 Title of each class Common Stock , par value $ 0.001 per share Registrant's telephone number , including area code : ( 206 ) 788-4545 20-8969493 ( I.R.S. Employer Identification No. ) Trading Symbol ALPN U 98102 ( Zip Code ) 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 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 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 and posted 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 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 . 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 . DOCUMENTS INCORPORATED BY REFERENCE Smaller reporting company 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 approximately $ 49.6 million . Shares of common stock held by each executive officer and director and by each other person who may be deemed to be an affiliate of the registrant , have been excluded from this computation . The determination of affiliate status for this purpose is not necessarily a conclusive determination for other purposes . The number of shares of the registrant's common stock outstanding as of March 10 , 2021 was 23,882,138 .