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UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON , D.C. 20549 FORM 10 - K ( 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 Delaware ( State or other jurisdiction of incorporation or organization ) Commission file number : 001-37378 ATYR PHARMA , INC . ( Exact name of registrant as specified in its charter ) 3545 John Hopkins Court , Suite # 250 , San Diego , CA ( Address of principal executive offices ) Registrant's telephone number , including area code ( 858 ) 731-8389 Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol LIFE Title of each class Common Stock , par value $ 0.001 per share 20-3435077 ( I.R.S. Employer Identification No. ) 92121 ( Zip Code ) Name of each exchange on which registered The Nasdaq Capital Market Yes 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 . 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 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 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 . O Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Act ) . Yes No The aggregate market value of the registrant's common stock held by non - affiliates of the registrant was approximately $ 25,388,988 based on the closing price of the registrant's common stock on the Nasdaq Capital Market of $ 4.44 per share on June 30 , 2020 , the last business day of the registrant's most recently completed second quarter . Shares of common stock held by each executive officer and director have been excluded from this calculation . This determination of affiliate status may not be conclusive for other purposes . The number of outstanding shares of the registrant's common stock , par value $ 0.001 per share , as of March 19 , 2021 was 16,011,385 . DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant's proxy statement to be filed with the Securities and Exchange Commission ( SEC ) , pursuant to Regulation 14A in connection with the registrant's 2021 Annual Meeting of Stockholders , which will be filed subsequent to the date hereof , are incorporated by reference into Part III of this annual report on Form 10 K. Such proxy statement will be filed with the SEC not later than 120 days following the end of the registrant's fiscal year ended December 31 , 2020 .