SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

_______________

SCHEDULE 13D/A

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT
TO RULE 13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO
RULE 13d-2(a)

Under the Securities Exchange Act of 1934

(Amendment No. 2)

Mercury Systems, Inc.

(Name of Issuer)

Common Stock, par value $0.01 per share

(Title of Class of Securities)

589378108

(CUSIP Number)

Eleazer Klein, Esq.

Marc Weingarten, Esq.

919 Third Avenue

New York, New York 10022

(212) 756-2000

(Name, Address and Telephone Number of Person

Authorized to Receive Notices and Communications)

February 3, 2023

(Date of Event which Requires

Filing of this Schedule)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following box. [ ]

NOTE: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Rule 13d-7 for other parties to whom copies are to be sent.

(Continued on following pages)

(Page 1 of 5 Pages)

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The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No. 589378108 SCHEDULE 13D/A Page 2 of 5 Pages

1	NAME OF REPORTING PERSON JANA PARTNERS LLC
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) ¨ (b) ¨
3	SEC USE ONLY
4	SOURCE OF FUNDS AF
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)		¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER 2,687,869 Shares
	8	SHARED VOTING POWER 0
	9	SOLE DISPOSITIVE POWER 2,687,869 Shares
	10	SHARED DISPOSITIVE POWER 0
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH PERSON 2,687,869 Shares
12	CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES			¨
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) (see Item 5) 4.6%
14	TYPE OF REPORTING PERSON IA

CUSIP No. 589378108 SCHEDULE 13D/A Page 3 of 5 Pages

The following constitutes Amendment No. 2 to the Schedule 13D filed by the undersigned (“Amendment No. 2”). This Amendment No. 2 amends the Schedule 13D as specifically set forth herein. Capitalized terms used herein and not otherwise defined in this Amendment No. 2  have the meanings set forth in the Schedule 13D.  

Item 3. SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION.

Item 3 of the Schedule 13D is hereby amended and restated in its entirety as follows:

The 2,687,869 Shares reported herein by JANA were acquired at an aggregate purchase price of approximately $132 million. Such Shares were acquired with investment funds in accounts managed by JANA and margin borrowings described in the following sentence. Such Shares are held by the investment funds managed by JANA in commingled margin accounts, which may extend margin credit to JANA from time to time, subject to applicable federal margin regulations, stock exchange rules and credit policies. In such instances, the positions held in the margin accounts are pledged as collateral security for the repayment of debit balances in the account. The margin accounts bear interest at a rate based upon the broker’s call rate from time to time in effect. Because other securities are held in the margin accounts, it is not possible to determine the amounts, if any, of margin used to purchase the Shares reported herein.

Item 4. PURPOSE OF TRANSACTION.

Item 4 of the Schedule 13D is hereby amended and supplemented as follows:

JANA appreciates the constructive dialogue it has had with the Board and management and applauds the Board’s decision to enhance shareholder value by engaging financial advisors and exploring a sale.

Item 5. INTEREST IN SECURITIES OF THE COMPANY.

Items 5(a), (b), (c) and (e) of the Schedule 13D are hereby amended and restated in their entirety as follows:

(a) The aggregate percentage of Shares reported to be beneficially owned by the Reporting Person is based upon 57,982,430 Shares outstanding as of October 31, 2022, as reported in the Issuer’s Quarterly Report on Form 10-Q for the quarterly period ended September 30, 2022 filed with the SEC on November 8, 2022.

As of the close of business on the date hereof, JANA may be deemed to beneficially own 2,687,869 Shares, representing approximately 4.6% of the Shares outstanding.

(b) The Reporting Person has sole voting and dispositive power over the 2,687,869 Shares, which power is exercised by the Principal.

(c) Information concerning transactions in the Shares effected by the Reporting Person during the past sixty (60) days is set forth in Exhibit E hereto and is incorporated herein by reference. All of the transactions in Shares listed hereto were effected in the open market through various brokerage entities.

(e) February 1, 2023.

Item 7. MATERIAL TO BE FILED AS EXHIBITS.

Item 7 of the Schedule 13D is hereby amended and supplemented as follows:

Exhibit E: Transactions in the Shares of the Issuer During the Past Sixty (60) Days.

CUSIP No. 589378108 SCHEDULE 13D/A Page 4 of 5 Pages

SIGNATURES

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.

Dated: February 3, 2023

JANA PARTNERS LLC
By:	/s/ Jennifer Fanjiang
Name:	Jennifer Fanjiang
Title:	Partner, Chief Legal Officer and Chief Compliance Officer

CUSIP No. 589378108 SCHEDULE 13D/A Page 5 of 5 Pages

EXHIBIT E

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

The following tables set forth all transactions in the Shares effected during the past sixty (60) days by the Reporting Person. Except as noted below, all such transactions were effected in the open market through brokers and the price per share includes commissions. Where a price range is provided in the column Price Range ($), the price reported in that row's Price Per Share ($) column is a weighted average price. These Shares were purchased/sold in multiple transactions at prices between the price ranges indicated in the Price Range ($) column. The Reporting Person will undertake to provide to the staff of the SEC, upon request, full information regarding the number of Shares purchased/sold at each separate price.

Trade Date	Shares Purchased (Sold)	Price Per Share ($)	Price Range ($)
02/01/2023	(241,645)	56.85	56.40 – 57.07
02/02/2023	(50,000)	56.02	55.91  – 56.44
02/03/2023	(76,142)	55.42	55.29 – 55.75