X0609 4 2026-08-21 0001049521 MERCURY SYSTEMS INC MRCY 0001436044 Ballhaus William L false 50 MINUTEMAN ROAD ANDOVER MA 01810 1 1 Chairman, President & CEO 0 Common Stock 2026-08-21 4 M 0 92850 42.00 A 321047.325 D Common Stock 2026-08-21 4 S 0 64796 92.404 D 256251.325 D Common Stock 2026-08-21 4 S 0 204 93.508 D 256047.325 D Common Stock 2026-08-24 4 M 0 140650 42.00 A 396697.325 D Common Stock 2026-08-24 4 M 0 11348 43.00 A 408045.325 D Common Stock 2026-08-24 4 S 0 105471 89.473 D 302574.325 D Common Stock 2026-08-24 4 S 0 2738 90.60 D 299836.325 D Common Stock 1403 I 401K Plan Common Stock 7066.173 I By Milestone Road Holdings, LLC Employee Stock Option (Right to Buy) 42.00 2026-08-21 4 M 0 92850 0 D 2026-08-17 2027-08-17 Common Stock 92850 140650 D Employee Stock Option (Right to Buy) 42.00 2026-08-24 4 M 0 140650 0 D 2026-08-17 2027-08-17 Common Stock 140650 0 D Employee Stock Option (Right to Buy) 43.00 2026-08-24 4 M 0 11348 0 D 2026-08-17 2027-08-17 Common Stock 11348 222152 D Represents the exercise of a stock option award scheduled to expire on August 17, 2027. Represents the sale of shares intended solely to cover the exercise price, applicable withholding taxes and related transaction costs of stock options exercised on the same date. This transaction was executed in multiple trades at prices ranging from $92.300 to $92.910. The price reported above reflects the weighted average purchase price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. This transaction was executed in multiple trades at prices ranging from $93.505 to $93.680. The price reported above reflects the weighted average purchase price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. This transaction was executed in multiple trades at prices ranging from $89.170 to $90.150. The price reported above reflects the weighted average purchase price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. This transaction was executed in multiple trades at prices ranging from $90.250 to $90.735. The price reported above reflects the weighted average purchase price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. /s/ Douglas Munro, attorney-in-fact 2026-08-25