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Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 For the fiscal year ended December 31 , 2020 Title of Each Class : Common Stock , $ 0.00001 par value FORM 10 - K ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 Incorporated under the Laws of the State of Delaware ACLARIS THERAPEUTICS , INC . Large accelerated filer Commission file number 001-37581 640 Lee Road , Suite 200 Wayne , PA 19087 ( 484 ) 324-7933 Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) ACRS I.R.S. Employer Identification No. Accelerated filer 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 15 ( d ) of the Exchange Act . Yes No □ 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 No 46-0571712 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 □ Name of Each Exchange on which Registered The Nasdaq Stock Market , LLC Indicate by check mark whether the registrant is a large accelerated filer , an accelerated filer , a non - accelerated filer , a smaller reporting company or 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 . 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 . Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Exchange Act ) . Yes No As of June 30 , 2020 , the last business day of the registrant's last completed second quarter , the aggregate market value of the registrant's common stock held by non - affiliates of the registrant was approximately $ 65.5 million based on the closing price of the registrant's common stock , as reported by the Nasdaq Global Select Market , on such date . As of January 31 , 2021 , 51,804,258 shares of common stock , $ 0.00001 par value , were outstanding . DOCUMENTS INCORPORATED BY REFERENCE Portions of the Company's definitive proxy statement , to be filed pursuant to Regulation 14A under the Securities Exchange Act of 1934 , for its 2021 Annual Meeting of Stockholders are incorporated by reference in Part III of this Form 10 - K .