# EDGAR Filing Document

**Accession Number:** 0001049521
**File Stem:** 0000902664-25-004832
**Filing Date:** 2025-11
**Character Count:** 8326
**Document Hash:** d63d2e2818fd25518b02f9f2016f7828
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000902664-25-004832.hdr.sgml**: 20251110

**ACCESSION NUMBER**: 0000902664-25-004832

**CONFORMED SUBMISSION TYPE**: SCHEDULE 13D/A

**PUBLIC DOCUMENT COUNT**: 2

**FILED AS OF DATE**: 20251110

**DATE AS OF CHANGE**: 20251110

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** MERCURY SYSTEMS INC
- **CENTRAL INDEX KEY:** 0001049521
- **STANDARD INDUSTRIAL CLASSIFICATION:** ELECTRONIC COMPONENTS & ACCESSORIES [3670]
- **ORGANIZATION NAME:** 04 Manufacturing
- **EIN:** 042741391
- **STATE OF INCORPORATION:** MA
- **FISCAL YEAR END:** 0630

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-52823
- **FILM NUMBER:** 251467774

**BUSINESS ADDRESS:**
- **STREET 1:** 50 MINUTEMAN ROAD
- **CITY:** ANDOVER
- **STATE:** MA
- **ZIP:** 01810
- **BUSINESS PHONE:** 9782561300

**MAIL ADDRESS:**
- **STREET 1:** 50 MINUTEMAN ROAD
- **CITY:** ANDOVER
- **STATE:** MA
- **ZIP:** 01810

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** MERCURY COMPUTER SYSTEMS INC
- **DATE OF NAME CHANGE:** 19971112
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** JANA Partners Management, LP
- **CENTRAL INDEX KEY:** 0001998597

**ORGANIZATION NAME:**
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A

**BUSINESS ADDRESS:**
- **STREET 1:** 888 SEVENTH AVENUE
- **STREET 2:** 24TH FLOOR
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10106
- **BUSINESS PHONE:** 212-455-0900

**MAIL ADDRESS:**
- **STREET 1:** 888 SEVENTH AVENUE
- **STREET 2:** 24TH FLOOR
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10106

## Ex-99

**<u>SCHEDULE A</u>**

**Transactions in the Shares of the Issuer in the Past Sixty (60) Days**

The following table sets forth all transactions in the Shares effected in the past sixty (60) days by the Reporting Person. All such transactions were effected in the open market through brokers and the price per share includes commissions.

---

| | | |
|:---|:---|:---|
| &nbsp;&nbsp;**Trade Date** | &nbsp;&nbsp;**Shares Purchased (Sold)** | &nbsp;&nbsp;**Price Per Share ($)** |
| &nbsp;&nbsp;11/06/2025\* | &nbsp;&nbsp;(1000000) | &nbsp;&nbsp;75.45 |

---

\* The transaction reported herein was effected for the purpose of rebalancing the holdings of funds and accounts managed by JANA.

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## SCHEDULE 13D

### Under the Securities Exchange Act of 1934

**(Amendment No. 3)**

**MERCURY SYSTEMS INC**

*(Name of Issuer)*

**Common Stock, par value $0.01 per share**

*(Title of Class of Securities)*

**589378108**

*(CUSIP Number)*

**Ele Klein & Adriana Schwartz**<br>McDermott Will & Schulte LLP<br>919 Third Avenue<br>New York NY 10022<br>212-756-2000

*(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)*

**11/06/2025**

*(Date of Event Which Requires Filing of this Statement)*

| **CUSIP No.** | **589378108** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**JANA Partners Management, LP** | Name of reporting person<br>**JANA Partners Management, LP** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**AF** | Source of funds (See Instructions)<br>**AF** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**4966675.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**4966675.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**4966675.00** | Aggregate amount beneficially owned by each reporting person<br>**4966675.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**8.3%** | Percent of class represented by amount in Row (11)<br>**8.3%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IA** | Type of Reporting Person (See Instructions)<br>**IA** | |

---

**Item 1. Security and Issuer**

**(a) Title of Class of Securities:**
Common Stock, par value $0.01 per share

**(b) Name of Issuer:**
MERCURY SYSTEMS INC

**(c) Address of Issuer's Principal Executive Offices:**
50 Minuteman Road, Andover, MA, 01810

This Amendment No. 3 ("Amendment No. 3") amends and supplements the statement on Schedule 13D filed with the SEC on September 22, 2022 (as amended from time to time, the "Schedule 13D") with respect to the Shares of the Issuer. This Amendment No. 3 amends Items 5 and 6 as set forth below. Capitalized terms used herein and not otherwise defined in this Amendment No. 3 have the meanings set forth in the Schedule 13D.

**Item 5. Interest in Securities of the Issuer**

**(a)**
Item 5(a) of the Schedule 13D is hereby amended and restated in its entirety as follows:

The aggregate percentage of Shares reported to be beneficially owned by the Reporting Person is based upon 60,100,136 Shares outstanding as of October 31, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q for the quarterly period ended September 26, 2025, filed with the SEC on November 4, 2025.

As of the close of business on the date hereof, JANA may be deemed to beneficially own 4,966,675 Shares, representing approximately 8.3% of the Shares outstanding.  This includes 4,832 deferred stock units ("DSUs") granted to Mr. Ostfeld on October 23, 2024 and 2,362 DSUs granted to Mr. Ostfeld on October 22, 2025, for his service on the Board of Directors of the Issuer (the "Board"). The DSUs vest on the earlier of the first anniversary of the grant date and the next annual meeting of shareholders. Vested DSUs do not convert into Shares until the date on which Mr. Ostfeld ceases to be a member of the Board. Mr. Ostfeld has assigned all rights to any Shares issuable pursuant to the grant to the Reporting Person. Pursuant to the assignment, settlement of the award on vesting will be made to the Reporting Person.

**(b)**
Item 5(b) of the Schedule 13D is hereby amended and restated in its entirety as follows:

The Reporting Person has sole voting and dispositive power over 4,966,675 Shares, which power is exercised by the Principal.

**(c)**
Item 5(c) of the Schedule 13D is hereby amended and restated in its entirety as follows:

Information concerning transactions in the Shares effected by the Reporting Person in the past sixty (60) days is set forth in Schedule A hereto and is incorporated herein by reference. All of the transactions in Shares listed therein were effected in the open market through various brokerage entities.  In addition, as disclosed in Item 5(a), on October 22, 2025, 2,362 DSUs were granted to Mr. Ostfeld for his service on the Board.

**Item 6. Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer.**

Item 6 of the Schedule 13D is hereby amended and supplemented as follows:

The information disclosed in Item 5(a) is incorporated herein by reference.

### SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** JANA Partners Management, LP

**Signature:** /s/ Jennifer Fanjiang

**Name/Title:** Jennifer Fanjiang, Partner, Chief Legal Officer and Chief Compliance Officer

**Date:** 11/10/2025