Mercury Systems: Stuart Kupinsky sells 1,000 shares

Mercury Systems Inc. EVP, CLO & Corp Sec Stuart Kupinsky sold 1,000 shares of common stock at $76 per share on October 21, 2026, under a Rule 10b5-1 trading plan adopted May 7, 2026.

Rhea-AI Filing Summary

Mercury Systems Inc. EVP, CLO & Corp Sec Stuart Kupinsky sold 1,000 shares of common stock at $76 per share on October 21, 2026, under a Rule 10b5-1 trading plan adopted May 7, 2026. After the sale, he reported 59,971 shares held directly and 1,283 shares held indirectly through a 401K Plan.

Insider Trade Summary 10b5-1

Net Seller: 1,000 shares

Net Sell 2 txns

Insider KUPINSKY STUART

Role EVP, CLO & Corp Sec

Sold 1,000 shs ($76K)

Type	Security	Shares	Price	Value
Sale	Common Stock F1	1,000	$76.00	$76K
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 59,971 shares (Direct); Common Stock — 1,283 shares (Indirect, 401K Plan)

Footnotes (1)

1. F1. Represents the sale of shares effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on May 7, 2026.

Key Figures

Common stock sold: 1,000 shares Sale price: $76 per share Direct shares following sale: 59,971 shares +1 more

4 metrics

Common stock sold 1,000 shares October 21, 2026

Sale price $76 per share October 21, 2026

Direct shares following sale 59,971 shares Reported after the October 21, 2026 sale

Shares held through 401K Plan 1,283 shares Indirect holdings reported October 21, 2026

Key Terms

Rule 10b5-1 trading plan, 401K Plan

2 terms

Rule 10b5-1 trading plan regulatory

"sale of shares effected pursuant to a Rule 10b5-1 trading plan"

A Rule 10b5-1 trading plan is a pre-arranged schedule that allows company insiders to buy or sell stock at specific times, even if they have inside information. It helps prevent accusations of unfair trading by making these transactions look planned and transparent, rather than sneaky or illegal.

401K Plan financial

"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

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

How many MRCY shares did Stuart Kupinsky sell, and at what price?

Stuart Kupinsky sold 1,000 shares of Mercury Systems common stock at $76 per share on October 21, 2026. The sale was under a Rule 10b5-1 trading plan adopted May 7, 2026.

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

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Available on EDGAR 10/26/2026 - 07:26 AM EDT Accepted by SEC EDGAR 10/26/2026 - 07:26 AM EDT 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).

X

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^*

KUPINSKY STUART

(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)
	EVP, CLO & Corp Sec

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
10/21/2026

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)
			Code	V	Amount	(A) or (D)	Price
Common Stock	10/21/2026		S		1,000(1)	D	$76	59,971	D
Common Stock								1,283	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 the sale of shares effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on May 7, 2026.

	/s/ Douglas Munro, attorney-in-fact	10/23/2026
	** 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)