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( 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 П TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 Delaware For the transition period from to Commission File Number 001-36510 LARIMAR THERAPEUTICS , INC . ( State or other jurisdiction of incorporation or organization ) Three Bala Plaza East , Suite 506 Bala Cynwyd , Pennsylvania ( Exact name of registrant as specified in its charter ) ( Address of principal executive offices ) Securities registered pursuant to Section 12 ( b ) of the Act : Title of each class ( 844 ) 511-9056 ( Registrant's telephone number , including area code ) Trading Symbol ( s ) LRMR 20-3857670 ( I.R.S. Employer Identification No. ) 19004 ( Zip Code ) Name of each exchange on which registered The Nasdaq Global Market Common Stock , par value $ 0.001 per share 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 Section 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 □ Act . 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 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 . 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 On the last business day of the most recently completed second fiscal quarter , the aggregate market value ( based on the closing sale price of its common stock on that date ) of the voting and non - voting stock held by non - affiliates of the registrant was $ 123.3 million . As of March 2 , 2021 , the registrant had 15,367,730 shares of the registrant's Common Stock , $ 0.001 par value per share , outstanding . DOCUMENTS INCORPORATED BY REFERENCE Part III of this Annual Report on Form 10 - K incorporates certain information by reference from the registrant's proxy statement for the 2021 annual meeting of shareholders to be filed no later than 120 days after the end of the registrant's fiscal year ended December 31 , 2020 .