Mercury Systems SVP granted 2,882 RSUs

Form 4/A for MRCY corrects a prior omission by adding a three-year RSU grant to the company’s SVP and CAO.

This filing corrects an earlier one, and you can read the original Form 4 if you want to see what changed.

Rhea-AI Filing Summary

MERCURY SYSTEMS INC (symbol: MRCY) is the issuer of record for a Form 4/A filing submitted to the SEC. Munro Douglas reported acquisition or exercise transactions in this Form 4 filing.

MERCURY SYSTEMS INC (MRCY) reports that Senior Vice President and Chief Accounting Officer Douglas Munro received a grant of 2,882 shares of common stock on August 17, 2026 as a compensation-related award. These are restricted stock units that vest in equal annual increments over three years, leaving him with 17,015 directly held shares plus 359 shares held indirectly through a 401K Plan after the grant. The amendment corrects a prior omission of this award and states no transactions were made under a Rule 10b5-1 trading plan.

Insider Trade Summary

Grant/Award: 2,882 shares

Grant/Award 2 txns

Insider Munro Douglas

Role SVP, CAO

Type	Security	Shares	Price	Value
Grant/Award	Common Stock F1	2,882	$0.00	$0.00
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 17,015 shares (Direct); Common Stock — 359 shares (Indirect, 401K Plan)

Footnotes (1)

1. F1. Represents restricted stock units that vest in equal annual increments over the three-year period following the grant date.

Key Figures

Restricted stock units granted: 2,882 shares Direct holdings after transaction: 17,015 shares Indirect holdings (401K Plan): 359 shares +2 more

5 metrics

Restricted stock units granted 2,882 shares Award of common stock to Douglas Munro on August 17, 2026

Direct holdings after transaction 17,015 shares Douglas Munro’s directly held MRCY shares following the grant

Indirect holdings (401K Plan) 359 shares MRCY shares held indirectly through a 401K Plan after the grant

Vesting period 3 years Restricted stock units vest in equal annual increments over three years

Grant price per share $0.00 Compensation-related restricted stock unit grant with no cash price per share

Key Terms

restricted stock units, 401K Plan, Rule 10b5-1

3 terms

restricted stock units financial

"Represents restricted stock units that vest in equal annual increments"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

401K Plan financial

"shares held indirectly through a 401K Plan after the grant"

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.

Rule 10b5-1 regulatory

"Rule 10b5-1 trading plan checkbox is not marked for this filing"

Rule 10b5-1 is a regulation that allows company insiders to buy or sell their shares at predetermined times, even if they have access to non-public information. It acts like setting a schedule in advance for transactions, helping prevent accusations of unfair trading. This rule provides a way for insiders to plan trades transparently, giving investors confidence that these transactions are not based on hidden information.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did MERCURY SYSTEMS INC (MRCY) report in this Form 4/A?

The filing reports a grant of 2,882 shares of common stock to Senior Vice President and Chief Accounting Officer Douglas Munro on August 17, 2026 as a restricted stock unit award, correcting an earlier omission.

How do the 2,882 MRCY restricted stock units granted to Douglas Munro vest?

The 2,882 restricted stock units granted on August 17, 2026 vest in equal annual increments over three years following the grant date, according to the footnote disclosure.

What are Douglas Munro’s MRCY share holdings after the reported grant?

After the grant, Douglas Munro holds 17,015 MRCY shares directly. He also has 359 shares held indirectly through a 401K Plan, as reported in the holdings section.

Was the MRCY insider grant to Douglas Munro made under a Rule 10b5-1 trading plan?

No. The filing’s Rule 10b5-1 checkbox is not marked, indicating that the reported grant was not made pursuant to a Rule 10b5-1 trading plan.

Why is this MRCY Form 4/A labeled as an amendment?

It is an amendment because it corrects the inadvertent omission of the August 17, 2026 restricted stock unit grant to Douglas Munro from an earlier Form 4, according to the remarks section.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 09/15/2026 - 06:11 PM Accepted by SEC EDGAR 09/15/2026 - 06:10 PM Learn about SEC filing dates

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^*

Munro Douglas

(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)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
08/17/2026

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)
08/19/2026

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)
			Code	V	Amount	(A) or (D)	Price
Common Stock	08/17/2026		A		2,882(1)	A	$0	17,015	D
Common Stock								359	I	401K Plan

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)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. Represents restricted stock units that vest in equal annual increments over the three-year period following the grant date.

Remarks:

This amendment is being filed to correct the inadvertent omission of the grant of restricted stock units to the reporting person on August 17, 2026.

	/s/ Douglas Munro	09/15/2026
	** 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)