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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 July 2 , 2021 OR TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM ΤΟ COMMISSION FILE NUMBER 0-23599 MERCURY SYSTEMS , INC . ( Exact name of registrant as specified in its charter ) Massachusetts ( State or other jurisdiction of incorporation or organization ) 50 Minuteman Road Andover MA ( Address of principal executive offices ) Title of Each Class Common Stock , Par Value $ 0.01 Per Share 978-256-1300 ( Registrant's telephone number , including area code ) 04-2741391 ( I.R.S. Employer Identification No. ) SECURITIES REGISTERED PURSUANT TO SECTION 12 ( b ) OF THE SECURITIES EXCHANGE ACT OF 1934 : Trading Symbol 01810 ( Zip Code ) Name of Each Exchange on Which Registered Nasdaq Global Select Market MRCY SECURITIES REGISTERED PURSUANT TO SECTION 12 ( g ) OF THE SECURITIES EXCHANGE ACT OF 1934 : NONE 1 Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . Yes ý 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 ý 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 ý 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 ( § 229.405 of this chapter ) during the preceding 12 months ( or for such shorter period that the registrant was required to submit such files ) . Yes ý 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 . Large accelerated filer ý 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 report under Section 404 ( b ) of the Sarbanes - Oxley Act ( 15 U.S.C.762 ( b ) ) by the registered public accounting firm that prepared or issued its audit report . Yes ý No Indicate by check mark whether the registrant is a shell company ( as defined by Rule 12b - 2 of the Exchange Act ) . Yes No ý The aggregate market value of the Common Stock held by non - affiliates of the registrant was approximately $ 4.8 billion based upon the closing price of the Common Stock as reported on the Nasdaq Global Select Market on January 1 , 2021 , the last business day of the registrant's most recently completed second fiscal quarter . Shares of Common Stock outstanding as of July 31 , 2021 : 56,234,113 shares . DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant's definitive Proxy Statement for its 2021 Annual Meeting of Shareholders are incorporated by reference into Part III of this report . Exhibit Index on Page