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TABLE OF CONTENTS ( 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 Delaware Commission File Number 000-15006 CELLDEX THERAPEUTICS , INC . ( State or other jurisdiction of incorporation or organization ) ( Exact name of registrant as specified in its charter ) 13-3191702 ( I.R.S. Employer Identification No. ) Perryville III Building , 53 Frontage Road , Suite 220 , Hampton , New Jersey 08827 ( Address of principal executive offices ) ( Zip Code ) Registrant's telephone number , including area code : ( 908 ) 200-7500 Securities registered pursuant to Section 12 ( b ) of the Act : Name of Each Exchange Title of Each Class : Common Stock , par value $ .001 Trading Symbol ( s ) CLDX Securities registered pursuant to Section 12 ( g ) of the Act : None Where Registered : NASDAQ Capital Market 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 and post 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 . ( Check one ) : 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 . □ 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 as of June 30 , 2020 was $ 507 million . Exclusion of shares held by any person should not be construed to indicate that such person possesses the power , direct or indirect , to direct or cause the actions of the management or policies of the registrant , or that such person is controlled by or under common control with the registrant . The number of shares of common stock outstanding at March 22 , 2021 was 39,614,638 shares . DOCUMENTS INCORPORATED BY REFERENCE Portions of the definitive Proxy Statement for our 2021 Annual Meeting of Stockholders are incorporated by reference into Part III of this Report .