Company: MRCY
Filing Date: 2025-09-10
Form Type: DEF 14A
Source: 0001049521-25-000029
Chunk: 1

Company: MERCURY SYSTEMS INC
Filing Date: 2025-09-10
Form: DEF 14A
Chunk 1
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 II director and does not include any other matters relating to the election of directors, including, without limitation, the election of directors nominated by any Mercury shareholder.

The Board of Directors has fixed the close of business on August 25, 2025 as the record date for the meeting. All shareholders of record on that date are entitled to notice of and to vote at the meeting.

Your vote is important. Please vote by internet, telephone, or mail as soon as possible to ensure your vote is recorded promptly. Please also note that, if you wish to attend the meeting, you must request an admission ticket in advance by contacting us at annualmeeting@mrcy.com. To attend the meeting, please note the security procedures included on page 1 of the proxy statement.

Important Notice Regarding the Availability of Proxy Materials for the 2025 Annual Meeting of Shareholders to be held on October 22, 2025: The proxy statement and annual report to shareholders for our fiscal year ended June 27, 2025 are available at www.envisionreports.com/MRCY.

| By Order of the Board of Directors                            |
| Chairman of the Board, President, and Chief Executive Officer |

Andover, Massachusetts

September 10, 2025

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### EXECUTIVE SUMMARY
This executive summary is an overview of information that you will find elsewhere in this proxy statement. This summary does not contain all of the information that you should consider, and you should read the entire proxy statement carefully before voting.

#### Proposals and Board Recommendations
| No. |     | Proposal Summary                                                                                 |     | Board's Voting Recommendations |
| 1   |     | Election of Three Class I Directors and One Class II Director                                    |     | FOR each nominee               |
| 2   |     | Advisory Vote on Fiscal 2025 Executive Compensation ("Say-on-Pay")                               |     | FOR                            |
| 3   |     | Approval of 2025 Long Term Incentive Plan                                                        |     | FOR                            |
| 4   |     | Ratification of Appointment of Our Independent Registered Public Accounting Firm for Fiscal 2026 |     | FOR                            |

Cautionary Note on Forward-Looking Statements: This proxy statement contains certain forward-looking statements, as that term is defined in the Private Securities Litigation Reform Act of 1995, including those relating to our focus on enhanced execution of our strategic plan. You can identify these statements by the words "may," "will," "