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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 TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 Commission File Number 000-30347 CURIS , INC . ( Exact Name of Registrant as Specified in Its Charter ) Delaware ( State or other jurisdiction of incorporation or organization ) 128 Spring Street , Building C - Suite 500 , Lexington , Massachusetts , ( Address of principal executive offices ) ( Zip Code ) 617-503-6500 ( Registrant's telephone number , including area code ) Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) CRIS Title of Each Class Common Stock , $ 0.01 par value per share 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 x 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 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 . x Yes " No 04-3505116 Accelerated filer ( I.R.S. Employer Identification No. ) 02421 Non - accelerated filer X 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 ) . x 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 ” and “ smaller reporting company ” , and “ emerging growth company ” in Rule 12b - 2 of the Exchange Act . Large accelerated filer " Name of Each Exchange on Which Registered Nasdaq Global Market Smaller reporting company Emerging growth company 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 . 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 is a shell company ( as defined in Rule 12b - 2 of the Act ) . Yes No X The aggregate market value of the registrant's common stock held by non - affiliates of the registrant ( without admitting that any person whose shares are not included in such calculation is an affiliate ) based on the last reported sale price of the common stock on June 30 , 2020 was approximately $ 54.4 million . As of March 12 , 2021 , there were 91,507,498 shares of the registrant's common stock outstanding . DOCUMENTS INCORPORATED BY REFERENCE Specified portions of the registrant's proxy statement for the annual meeting of stockholders scheduled to be held on May 27 , 2021 , which are to be filed with the Commission not later than 120 days after the close of the Registrant's fiscal year ended December 31 , 2020 pursuant to Regulation 14A , have been incorporated by reference in Items 10-14 of Part III of this Annual Report on Form 10 - K .