Company: MRCY
Filing Date: 2025-09-10
Form Type: DEF 14A
Source: 0001049521-25-000029
Chunk: 0

Company: MERCURY SYSTEMS INC
Filing Date: 2025-09-10
Form: DEF 14A
Chunk 0
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### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION

#### Washington, D.C. 20549

#### SCHEDULE 14A

#### Proxy Statement Pursuant to Section 14(a) of the

#### Securities Exchange Act of 1934
Filed by the Registrant ý Filed by a Party other than the Registrant ¨

Check the appropriate box:

¨ Preliminary Proxy Statement

¨ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

ý Definitive Proxy Statement

¨ Definitive Additional Materials

¨ Soliciting Material Pursuant to §240.14a-12

#### Mercury Systems, Inc.
<div align='center'>(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)</div>

Payment of Filing Fee (Check all boxes that apply):

ý No fee required

¨ Fee paid previously with preliminary materials

¨ Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11

#### Notice of 2025 Annual Meeting of Shareholders
Dear Shareholders:

The Board of Directors of Mercury Systems, Inc. invites you to attend the 2025 Annual Meeting of Shareholders. The Annual Meeting will be held on October 22, 2025, at 10:00 a.m. Eastern Time at the Company's headquarters at 50 Minuteman Road, Andover, Massachusetts 01810. The meeting is being held for the following purposes:

• To elect three Class I directors nominated by the Board of Directors, each to serve for a three-year term, and in each case until their successors are duly elected and qualified, and to elect one Class II director nominated by the Board of Directors, to serve for a one-year term, until her successor is duly elected and qualified.

• To hold an advisory vote on the fiscal 2025 compensation of our named executive officers (the "say-on-pay" vote).

• To hold a vote to approve our 2025 Long Term Incentive Plan.

• To ratify the appointment of KPMG LLP as our independent registered public accounting firm for fiscal 2026.

• To consider and act upon any other business that may properly come before the meeting or any adjournment or postponement of the meeting.

The first proposal relates solely to the election of three Class I directors and one Class