Mercury Systems officer plans sale of 1,308 shares

MERCURY SYSTEMS INC (MRCY) is named as the issuer in a notice of proposed sales of its common stock under Rule 144 by officer Stuart Kupinsky.

Rhea-AI Filing Summary

MERCURY SYSTEMS INC (MRCY) is named as the issuer in a notice of proposed sales of its common stock under Rule 144 by officer Stuart Kupinsky. The notice covers planned sales of 1,308 shares of common stock through Fidelity Brokerage Services LLC on or after August 19, 2026. The securities relate to restricted stock vesting on August 18, 2026, received as compensation. The disclosure notes that the sale amount includes shares needed to cover a tax obligation arising from settlement of the vested equity award.

Key Figures

Shares proposed to be sold: 1,308 shares Aggregate market value of proposed sale: 131,200.25 Shares sold on August 17, 2026: 1,195 shares +3 more

6 metrics

Shares proposed to be sold 1,308 shares Common stock under Rule 144, with sale date of August 19, 2026

Aggregate market value of proposed sale 131,200.25 Value reported for 1,308 MRCY common shares to be sold

Shares sold on August 17, 2026 1,195 shares MRCY common stock sold by Stuart Kupinsky in prior three months

Transaction value on August 17, 2026 131,391.33 Aggregate value for 1,195 MRCY common shares sold

Shares sold on August 18, 2026 1,178 shares MRCY common stock sold by Stuart Kupinsky in prior three months

Transaction value on August 18, 2026 131,179.37 Aggregate value for 1,178 MRCY common shares sold

Key Terms

Rule 144, Restricted Stock Vesting, attorney-in-fact, tax obligation

4 terms

Rule 144 regulatory

"See the definition of "person" in paragraph (a) of Rule 144."

Rule 144 is a U.S. securities regulation that sets conditions under which restricted or insider-held shares can be legally resold to the public, such as required holding periods, availability of public information, limits on how much can be sold at once, and certain filing requirements. For investors it matters because it determines when previously locked-up shares can enter the market — like a release valve that can increase supply, affect share price, and signal insider intent.

Restricted Stock Vesting financial

"Common | 08/18/2026 | Restricted Stock Vesting | Issuer"

Restricted stock vesting is the timetable and conditions under which shares granted to employees or insiders become fully owned and can be sold, typically requiring continued work or meeting performance goals. It matters to investors because large blocks of shares can become tradable at once, which can change share supply and price, and because vesting aligns insiders’ incentives with the company’s long‑term performance—think of it like a timed unlock that both rewards and locks in key people.

attorney-in-fact regulatory

"as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact"

An attorney-in-fact is the person or entity given legal authority through a power of attorney to act on behalf of another for specific tasks, such as signing documents, voting shares, or handling transactions. For investors, this matters because it lets a trusted representative make timely decisions or complete paperwork when the owner cannot, much like handing keys to someone to run errands on your behalf—so checks on scope and limits of that authority are important.

tax obligation financial

"Sale includes an amount necessary to cover a tax obligation resulting from the settlement"

FAQ

What does the Form 144 notice disclose for MERCURY SYSTEMS INC (MRCY)?

It discloses that officer Stuart Kupinsky plans to sell 1,308 shares of MRCY common stock under Rule 144. The shares are tied to restricted stock that vested as compensation on August 18, 2026, with part of the sale covering tax obligations.

How many MRCY shares are proposed to be sold under this Rule 144 notice?

The notice covers a proposed sale of 1,308 shares of MERCURY SYSTEMS INC common stock. These shares are associated with a restricted stock vesting event and are expected to be sold through Fidelity Brokerage Services LLC starting August 19, 2026.

What prior sales of MRCY shares are reported for the past three months?

The notice lists prior sales by Stuart Kupinsky of 1,195 shares on August 17, 2026, and 1,178 shares on August 18, 2026. Each transaction involved MRCY common stock and is reported with its own total transaction value.

Why does the seller indicate part of the MRCY stock sale is needed for taxes?

The remarks state the sale includes an amount necessary to cover a tax obligation from settlement of a vested equity award. This means some of the MRCY shares sold are being used to satisfy tax liabilities triggered by the restricted stock vesting.

Who is executing the planned MRCY share sale and signing on behalf of the seller?

The planned sale will be executed through Fidelity Brokerage Services LLC. The notice is signed by Jennifer Ruchti as a duly authorized representative of Fidelity, acting as attorney-in-fact for the seller, Stuart Kupinsky.

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

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Available on EDGAR 08/19/2026 - 04:42 PM Accepted by SEC EDGAR 08/19/2026 - 04:41 PM Learn about SEC filing dates

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK	0001289593
Filer CCC	XXXXXXXX
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer	MERCURY SYSTEMS INC
SEC File Number	001-41194
Address of Issuer	50 MINUTEMAN ROAD ANDOVER MASSACHUSETTS 01810
Phone	9782561300
Name of Person for Whose Account the Securities are To Be Sold	KUPINSKY STUART
See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.
Relationship to Issuer	Officer

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common	Fidelity Brokerage Services LLC 900 Salem Street Smithfield RI 02917	1308	131200.25	60136133	08/19/2026	NASDAQ

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common	08/18/2026	Restricted Stock Vesting	Issuer			1308	08/18/2026	Compensation

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
Stuart Kupinsky 50 Minuteman Road Andover MA 01810	Common	08/17/2026	1195	131391.33
Stuart Kupinsky 50 Minuteman Road Andover MA 01810	Common	08/18/2026	1178	131179.37

144: Remarks and Signature

Remarks	Sale includes an amount necessary to cover a tax obligation resulting from the settlement of a vested equity award distribution.
Date of Notice	08/19/2026
ATTENTION:
The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.
Signature	/s/ Jennifer Ruchti, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Stuart Kupinsky
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)