Mercury Systems officer plans $86K stock sale

MERCURY SYSTEMS INC (MRCY) has a planned sale notice under Rule 144 for 1,000 shares of common stock held for the account of officer Stuart Kupinsky, to be sold through Fidelity Brokerage Services LLC.

Rhea-AI Filing Summary

MERCURY SYSTEMS INC (MRCY) has a planned sale notice under Rule 144 for 1,000 shares of common stock held for the account of officer Stuart Kupinsky, to be sold through Fidelity Brokerage Services LLC. The shares were acquired on February 15, 2025 via restricted stock vesting as compensation.

The notice also lists recent sales by Kupinsky over the prior three months, and reports 60,136,133 shares of this class outstanding on September 21, 2026; this is a baseline figure, not the amount being offered.

Key Figures

Shares to be sold under Rule 144: 1,000 shares Approximate aggregate sale price: $86,520.00 Shares outstanding: 60,136,133 shares +4 more

7 metrics

Shares to be sold under Rule 144 1,000 shares Common stock for account of officer Stuart Kupinsky

Approximate aggregate sale price $86,520.00 Planned sale of 1,000 common shares through Fidelity Brokerage Services LLC

Shares outstanding 60,136,133 shares Common stock outstanding as of September 21, 2026

Shares sold August 17, 2026 1,195 shares Common stock sold for $131,391.33

Shares sold August 18, 2026 1,178 shares Common stock sold for $131,179.37

Shares sold August 19, 2026 1,308 shares Common stock sold for $131,200.25

Shares sold August 21, 2026 1,000 shares Common stock sold for $95,230.00

Key Terms

Rule 144, restricted stock, attorney-in-fact, compensation

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 financial

"Common | 02/15/2025 | Restricted Stock Vesting | Issuer"

Shares granted to an individual that carry limits on transfer or sale until certain conditions are met, such as staying with the company for a set time or hitting performance targets. Think of them as a locked gift that gradually opens; for investors they matter because they affect how many shares may enter the market later, signal management incentives and potential dilution, and reveal confidence in future company performance.

attorney-in-fact regulatory

"as attorney-in-fact for Stuart Kupinsky"

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.

compensation financial

"02/15/2025 | Compensation"

FAQ

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

What does the Form 144 filing mean for MERCURY SYSTEMS INC (MRCY)?

It gives notice that 1,000 shares of MRCY common stock held for officer Stuart Kupinsky’s account may be sold under Rule 144 through Fidelity Brokerage Services LLC. It is a disclosure of a potential resale, not an issuance of new shares by the company.

How many MRCY shares are covered by this Rule 144 notice?

The notice covers 1,000 shares of MRCY common stock for potential sale. These shares were acquired on February 15, 2025 through restricted stock vesting as compensation from the issuer.

Who is the selling security holder in the MRCY Form 144?

The securities are being sold for the account of Stuart Kupinsky, identified as an officer of Mercury Systems Inc. Fidelity Brokerage Services LLC is listed as the brokerage firm handling the transaction.

What prior sales of MRCY shares by this person are disclosed?

The notice lists recent sales of MRCY common stock: 1,195 shares on August 17, 2026, 1,178 shares on August 18, 2026, 1,308 shares on August 19, 2026, and 1,000 shares on August 21, 2026, each with stated dollar amounts received.

How many MRCY shares are reported as outstanding in this Form 144?

The filing reports 60,136,133 shares of this class of Mercury Systems Inc common stock outstanding on September 21, 2026. This figure provides context and is not the amount being sold.

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

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Available on EDGAR 09/21/2026 - 12:40 PM Accepted by SEC EDGAR 09/21/2026 - 12:39 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	1000	86520.00	60136133	09/21/2026	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	02/15/2025	Restricted Stock Vesting	Issuer			1000	02/15/2025	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
Stuart Kupinsky 50 Minuteman Road Andover MA 01810	Common	08/19/2026	1308	131200.25
Stuart Kupinsky 50 Minuteman Road Andover MA 01810	Common	08/21/2026	1000	95230.00

144: Remarks and Signature

Remarks
Date of Notice	09/21/2026
Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1	05/07/2026
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)