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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 Commission file number 001-12505 CORE MOLDING TECHNOLOGIES , INC . ( Exact name of registrant as specified in its charter ) Delaware ( State or other jurisdiction incorporation or organization ) 800 Manor Park Drive , Columbus , Ohio ( Address of principal executive office ) to Title of each class Common Stock , par value $ 0.01 Preferred Stock purchase rights , par value $ 0.01 : Trading Symbol ( s ) CMT N / A 31-1481870 Registrant's telephone number , including area code : ( 614 ) 870-5000 Securities registered pursuant to Section 12 ( b ) of the Act : ( I.R.S. Employer Identification No. ) 43228-0183 ( Zip Code ) Name of each exchange on which registered NYSE American LLC NYSE American LLC Securities registered pursuant to Section 12 ( g ) of the Act : None ( Title of class ) 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