Grant4

MERCURY SYSTEMS INC

Total Value

Filing Date

Oct 30, 2026

1 transaction

Trade Summary

On Oct 28, 2026, Ostfeld Scott, Director, reported $0 of MERCURY SYSTEMS INC (MRCY) across 1 transaction. The filing covers Common Stock, par value $0.01 per share and reflects balanced net activity of $0. Insider transactions are sourced from SEC Form 4 disclosures and should be reviewed alongside company fundamentals and the insider's broader trading history.

Insider Information

Name: Ostfeld Scott
Role: Director
Location: NEW YORK, NY

Filing Details

Filing Date: Oct 30, 2026
Transaction Date: Oct 28, 2026
Accession Number: 0000902664-26-004313
Form Type: 4

Non-Derivative Transactions

Date	Security	Shares	Price	Type	Value
Oct 28, 2026	Common Stock, par value $0.01 per share	2,348	—	Grant/Award	—

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Footnotes

(F1)Represents deferred stock units ("DSUs") granted to Scott Ostfeld ("Mr. Ostfeld"), a Managing Partner and Portfolio Manager of JANA Partners Management, LP ("JANA"), in connection with his service on the Issuer's Board of Directors. 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 of common stock until the date on which Mr. Ostfeld ceases to be a member of the Issuer's Board of Directors.
(F2)Mr. Ostfeld has assigned all rights to any shares issuable pursuant to the grant to JANA. Pursuant to the assignment, settlement of the award on vesting will be made to JANA.

SEC Form 4

FORM 4

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

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Ostfeld Scott

(Last)

(First)

(Middle)

888 SEVENTH AVENUE, 24TH FLOOR

(Street)

NEW YORK

10106

(City)

(State)

(Zip)

2. Issuer Name and Ticker or Trading Symbol
MERCURY SYSTEMS INC [ MRCY ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director	10% Owner
	Officer (give title below)	Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
10/28/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock, par value $0.01 per share	10/28/2026		A		2,348⁽¹⁾	A	$0	0	I	See footnote⁽²⁾

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)

Explanation of Responses:

1. Represents deferred stock units ("DSUs") granted to Scott Ostfeld ("Mr. Ostfeld"), a Managing Partner and Portfolio Manager of JANA Partners Management, LP ("JANA"), in connection with his service on the Issuer's Board of Directors. 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 of common stock until the date on which Mr. Ostfeld ceases to be a member of the Issuer's Board of Directors.

2. Mr. Ostfeld has assigned all rights to any shares issuable pursuant to the grant to JANA. Pursuant to the assignment, settlement of the award on vesting will be made to JANA.

Remarks:

Based on the current structure of JANA, JANA will no longer file as a director-by-deputization for purposes of Section 16 under the Securities Exchange Act of 1934.

	/s/ Scott Ostfeld	10/30/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

Form 4 as rendered by the SEC from accession 0000902664-26-004313.

MERCURY SYSTEMS INC

Trade Summary

Company Information

Insider Information

Filing Details

Non-Derivative Transactions

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Footnotes

SEC Form 4

SEC Filing

SEC Form 4