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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 Commission File No. 000-49604 UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON , D.C. 20549 Title of each class Class A Common Stock Delaware ( State or other jurisdiction of incorporation ) 2251 Corporate Park Drive ( Address of principal executive offices ) Large accelerated filer Non - accelerated filer Emerging growth company ManTech International Corporation ( Exact name of registrant as specified in its charter ) ■ Herndon to VA ( 703 ) 218-6000 ( Registrant's telephone number , including area code ) Trading Symbol ( s ) MANT 22-1852179 ( IRS Employer Identification No. ) 20171 ( Zip Code ) Securities registered pursuant to Section 12 ( b ) of the Act : Name of each exchange on which registered Nasdaq 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 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 Securities registered pursuant to Section 12 ( g ) of the Act : None 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 the definitions of " large accelerated filer , " " accelerated filer , " " smaller reporting company , " and " emerging growth company " in Rule 12b - 2 of the Exchange Act . Accelerated filer Smaller reporting 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 voting stock held by non - affiliates of the registrant as of June 30 , 2020 was $ 1.85 billion ( based on the closing price of $ 68.49 per share on June 30 , 2020 , as reported by the Nasdaq Global Select Market ) . There were the following numbers of shares outstanding of each of the registrant's classes of common stock as of February 17 , 2021 : ManTech International Corp. Class A Common Stock , $ 0.01 par value per share , 27,325,395 shares ; ManTech International Corp. Class B Common Stock , $ 0.01 par value per share , 13,176,695 shares . DOCUMENTS INCORPORATED BY REFERENCE Certain portions of the definitive Proxy Statement to be filed with the Securities Exchange Commission pursuant to Regulation 14A in connection with the registrant's 2021 Annual Meeting of Stockholders , to be filed subsequent to the date hereof , are incorporated by reference into Part III ( Items 10 , 11 , 12 , 13 and 14 ) of this Annual Report on Form 10 - K . Such definitive Proxy Statement will be filed with the Commission not later than 120 days after the end of the fiscal year covered by this Annual Report on Form 10 - K .