United States securities and exchange commission logo March 10, 2021 Michael D. Ruppert Chief Financial Officer Mercury Systems, Inc. 50 Minuteman Road Andover, MA 01810 Re: Mercury Systems, Inc. Form 10-K for the Fiscal Year Ended July 2, 2020 Filed August 18, 2020 File No. 000-23599 Dear Mr. Ruppert: We have completed our review of your filing. We remind you that the company and its management are responsible for the accuracy and adequacy of their disclosures, notwithstanding any review, comments, action or absence of action by the staff. Sincerely, Division of Corporation Finance Office of Manufacturing