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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 For the transition period from Delaware ( State or Other Jurisdiction of Incorporation or Organization ) Title of Each Class : Common stock , $ 0.01 par value to Commission file number 001-10716 TRIMAS CORPORATION ( Exact Name of Registrant as Specified in Its Charter ) ( IRS Employer Identification No. ) 38505 Woodward Avenue , Suite 200 Bloomfield Hills , Michigan 48304 ( Address of Principal Executive Offices , Including Zip Code ) ( 248 ) 631-5450 ( Registrant's telephone number , including area code ) 38-2687639 Securities registered pursuant to Section 12 ( b ) of the Act : Trading symbol ( s ) . Name of Each Exchange on Which Registered : The NASDAQ Stock Market LLC TRS 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 Section 15 ( d ) of the Act . Yes 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 No 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 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 definition of " large accelerated filer , " " accelerated filer , " " smaller reporting company , " and " emerging growth company " in Rule 12b - 2 of the Exchange Act . 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 X The aggregate market value of the voting common equity held by non - affiliates of the Registrant as of June 30 , 2020 was approximately $ 1.0 billion , based upon the closing sales price of the Registrant's common stock , $ 0.01 par value , reported for such date on the NASDAQ Global Select Market . For purposes of this calculation only , directors , executive officers and the principal controlling shareholder or entities controlled by such controlling shareholder are deemed to be affiliates of the Registrant . As of February 19 , 2021 , the number of outstanding shares of the Registrant's common stock , $ 0.01 par value , was 43,178,165 shares . Portions of the Registrant's Proxy Statement for the 2021 Annual Meeting of Stockholders are incorporated herein by reference in Part III of this Annual Report on Form 10 K to the extent stated herein .