Mercury Systems CEO forfeits 70,287 performance shares

Q: What insider transaction did MRCY report for William L. Ballhaus on August 14, 2026?

William L. Ballhaus reported a disposition of 70,287 MRCY shares to the issuer on August 14, 2026. A footnote clarifies these shares were forfeited performance stock awards due to below-target performance, not an open-market sale.

Q: Were the 70,287 MRCY shares reported by William L. Ballhaus sold in the market?

No. The 70,287 shares represent performance stock awards forfeited because of below-target performance. The transaction is coded as a disposition to the issuer, indicating a forfeiture rather than a market sale.

Q: What indirect MRCY holdings does William L. Ballhaus report on this Form 4?

Ballhaus reports 1,403 MRCY shares held indirectly through a 401K Plan and 7,066.173 shares held indirectly by Milestone Road Holdings, LLC, in addition to his direct share ownership.

Q: Does the Form 4 for MRCY indicate use of a Rule 10b5-1 trading plan?

No. The filing’s Rule 10b5-1 checkbox is not marked, and there is no footnote indicating the disposition occurred under a pre-arranged Rule 10b5-1 trading plan or similar arrangement.

For MERCURY SYSTEMS INC (MRCY), Chairman, President & CEO William L. Ballhaus reported a disposition of 70,287 shares of Common Stock on August 14, 2026, described as a "Disposition to issuer".

Filing Impact

(Neutral)

Filing Sentiment

(Neutral)

Form Type

Rhea-AI Filing Summary

For MERCURY SYSTEMS INC (MRCY), Chairman, President & CEO William L. Ballhaus reported a disposition of 70,287 shares of Common Stock on August 14, 2026, described as a "Disposition to issuer". A footnote states these shares represent performance stock awards that were forfeited due to below-target performance, rather than sold in the market. Following this forfeiture, Ballhaus directly holds 304,689.325 shares. He also reports indirect holdings of 1,403 shares through a 401K Plan and 7,066.173 shares held by Milestone Road Holdings, LLC.

Insider Trade Summary

Disposition: 70,287 shares

Disposition 3 txns

Insider Ballhaus William L

Role Chairman, President & CEO

Type	Security	Shares	Price	Value
Disposition	Common Stock ^F1	70,287	$0.00	$0.00
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 304,689.325 shares (Direct); Common Stock — 1,403 shares (Indirect, 401K Plan); Common Stock — 7,066.173 shares (Indirect, By Milestone Road Holdings, LLC)

Footnotes (1)

F1. Represents shares underlying performance stock awards that were forfeited as a result of below-target performance.

Key Figures

Shares forfeited to issuer: 70,287 shares Direct holdings after transaction: 304,689.325 shares Indirect 401K holdings: 1,403 shares +2 more

5 metrics

Shares forfeited to issuer 70,287 shares Performance stock awards forfeited due to below-target performance on August 14, 2026

Direct holdings after transaction 304,689.325 shares Common stock directly owned by William L. Ballhaus following the disposition

Indirect 401K holdings 1,403 shares Common stock held indirectly through a 401K Plan after the reported transaction

Indirect LLC holdings 7,066.173 shares Common stock held indirectly by Milestone Road Holdings, LLC after the reported transaction

Transaction price per share $0.0000 Reported per-share amount for the disposition to issuer of forfeited performance stock awards

Key Terms

Disposition to issuer, performance stock awards, below-target performance, indirect, +1 more

5 terms

Disposition to issuer financial

"transaction code description is listed as "Disposition to issuer""

performance stock awards financial

"Represents shares underlying performance stock awards that were forfeited"

below-target performance financial

"were forfeited as a result of below-target performance"

indirect financial

"ownership_type is indirect for certain holdings"

401K Plan financial

"nature_of_ownership is listed as 401K Plan"

A 401(k) plan is an employer-sponsored retirement savings account that lets workers set aside part of their paycheck into investments, often with tax breaks and sometimes with matching contributions from the employer. Think of it as a workplace piggy bank that grows through employee contributions, optional company top-ups, and market returns; it matters to investors because it shapes household retirement security, drives large flows of money into public markets, and affects a company’s compensation costs and ability to attract and keep talent.

FAQ

What insider transaction did MRCY report for William L. Ballhaus on August 14, 2026?

William L. Ballhaus reported a disposition of 70,287 MRCY shares to the issuer on August 14, 2026. A footnote clarifies these shares were forfeited performance stock awards due to below-target performance, not an open-market sale.

Were the 70,287 MRCY shares reported by William L. Ballhaus sold in the market?

No. The 70,287 shares represent performance stock awards forfeited because of below-target performance. The transaction is coded as a disposition to the issuer, indicating a forfeiture rather than a market sale.

How many MRCY shares does William L. Ballhaus hold directly after this Form 4?

After the reported forfeiture, William L. Ballhaus directly holds 304,689.325 shares of MRCY common stock. This figure reflects his direct ownership position following the disposition to the issuer of performance-based awards.

What indirect MRCY holdings does William L. Ballhaus report on this Form 4?

Ballhaus reports 1,403 MRCY shares held indirectly through a 401K Plan and 7,066.173 shares held indirectly by Milestone Road Holdings, LLC, in addition to his direct share ownership.

Does the Form 4 for MRCY indicate use of a Rule 10b5-1 trading plan?

No. The filing’s Rule 10b5-1 checkbox is not marked, and there is no footnote indicating the disposition occurred under a pre-arranged Rule 10b5-1 trading plan or similar arrangement.

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Available on EDGAR 08/18/2026 - 06:17 PM Accepted by SEC EDGAR 08/18/2026 - 06:16 PM

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^*

Ballhaus William L

(Last)

(First)

(Middle)

50 MINUTEMAN ROAD

(Street)

ANDOVER

MASSACHUSETTS

01810

(City)

(State)

(Zip)

UNITED STATES

(Country)

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
X	Officer (give title below)	Other (specify below)
	Chairman, President & CEO

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
08/14/2026

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

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

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

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	08/14/2026		D		70,287⁽¹⁾	D	$0	304,689.325	D
Common Stock								1,403	I	401K Plan
Common Stock								7,066.173	I	By Milestone Road Holdings, LLC

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 shares underlying performance stock awards that were forfeited as a result of below-target performance.

	/s/ Douglas Munro, attorney-in-fact	08/18/2026
	** 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: SEC 1474 (03-26)

Source: View Original Filing on SEC EDGAR