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( 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 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 Form 10 - K 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 ) 300 Granite Street , Suite 201 Braintree , MA ( Address of principal executive offices ) Securities registered pursuant to Section 12 ( b ) of the Act : ALTRA INDUSTRIAL MOTION CORP . ( Exact name of registrant as specified in its charter ) Large accelerated filer Non - accelerated filer X to Commission file number : 001-33209 Registrant's telephone number , including area code : ( 781 ) 917-0600 Title of Each Class Common Stock , $ 0.001 par value 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 No D Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15 ( d ) of the Act . Yes ☐ No 区 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 during the preceding 12 months ( or for such shorter period that the registrant was required to submit such files ) . Yes No □ Trading Symbol 61-1478870 ( I.R.S. Employer Identification No. ) 02184 ( Zip Code ) AIMC Indicate by check mark whether the registrant is a large accelerated filer , an accelerated filer , a non - accelerated filer , or a 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 .: Document Altra Industrial Motion Corp. Proxy Statement for the 2021 Annual Meeting of Stockholders Name of Each Exchange on Which Registered NASDAQ Global Select Market 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 by the registered public accounting firm that prepared or issued its audit report . No Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Exchange Act ) . Yes The aggregate market value of the voting and non - voting common stock held by non - affiliates of the registrant based on the closing price ( as reported by the NASDAQ Global Market ) of such common stock on the last business day of the registrant's most recently completed second fiscal quarter ( June 30 , 2020 ) was approximately $ 2.30 billion . As of February 25 , 2021 , there were 64,807,253 shares of Common Stock , $ 0.001 par value per share , outstanding . DOCUMENTS INCORPORATED BY REFERENCE : Portions of the following document are incorporated herein by reference into the Part of the Form 10 - K indicated . Part of Form 10 - K into which Incorporated ooo Part III