Mercury Systems officer plans sale of 548 shares

MERCURY SYSTEMS INC (MRCY) insider Douglas Munro, identified as an officer, has filed a notice of proposed sale of company securities under Rule 144.

Rhea-AI Filing Summary

MERCURY SYSTEMS INC (MRCY) insider Douglas Munro, identified as an officer, has filed a notice of proposed sale of company securities under Rule 144. The notice covers the planned sale of 548 shares of MRCY common stock held at Fidelity Brokerage Services LLC, with an indicated value of $54,967.69 as of August 19, 2026 on NASDAQ. The shares derive from a restricted stock vesting event on August 18, 2026 and are classified as compensation. Munro also reports prior sales over the past three months of 404 shares for $44,420.17 on August 17, 2026 and 494 shares for $55,010.70 on August 18, 2026. The filing notes that the sale includes shares needed to cover a tax obligation from the vested equity award.

Key Figures

Planned shares to be sold: 548 shares Indicated value of planned sale: $54,967.69 Shares sold 08/17/2026: 404 shares +4 more

7 metrics

Planned shares to be sold 548 shares Common stock covered by proposed Rule 144 sale held at Fidelity

Indicated value of planned sale $54,967.69 Value associated with 548 shares as of 08/19/2026

Shares sold 08/17/2026 404 shares Common stock sold by Douglas Munro during past 3 months

Proceeds 08/17/2026 $44,420.17 Value of 404 MRCY shares sold on 08/17/2026

Shares sold 08/18/2026 494 shares Common stock sold by Douglas Munro during past 3 months

Proceeds 08/18/2026 $55,010.70 Value of 494 MRCY shares sold on 08/18/2026

Notice date 08/19/2026 Date of Rule 144 notice filing for planned sale

Key Terms

Rule 144, restricted stock vesting, equity award, 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 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.

equity award financial

"resulting from the settlement of a vested equity award distribution."

An equity award is a form of pay where a company gives employees, executives or other stakeholders the right to own or buy company shares—either immediately or after meeting certain conditions. Think of it like receiving slices of the company pie now or coupons to claim slices later; it matters to investors because it affects ownership dilution, executive incentives and reported compensation costs, and signals how management is being rewarded and retained.

compensation financial

"548 | 08/18/2026 | Compensation"

FAQ

What insider transaction is disclosed for MRCY in this Form 144?

Douglas Munro, an officer of MERCURY SYSTEMS INC (MRCY), filed to sell 548 shares of common stock under Rule 144. These shares come from a restricted stock vesting event on August 18, 2026 and are held at Fidelity Brokerage Services LLC.

How many MRCY shares has Douglas Munro sold recently?

Douglas Munro reports selling 404 shares of MRCY on August 17, 2026 for $44,420.17 and 494 shares on August 18, 2026 for $55,010.70. These transactions are disclosed as sales during the past three months.

What is the value of the MRCY shares Douglas Munro plans to sell?

The planned sale covers 548 shares of MRCY common stock with an indicated value of $54,967.69 as of August 19, 2026. This figure is tied to the securities held at Fidelity Brokerage Services LLC for trading on NASDAQ.

Why is Douglas Munro selling MRCY shares according to the filing?

The filing states the sale includes an amount necessary to cover a tax obligation from the settlement of a vested equity award. The shares to be sold are identified as arising from a restricted stock vesting event treated as compensation.

Under what rule are the MRCY shares being sold by Douglas Munro?

The sale is being made under Rule 144, which governs resales of restricted and control securities. The notice provides details on the number of MRCY shares, their origin from restricted stock vesting, and recent sales in the past three months.

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

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Available on EDGAR 08/19/2026 - 04:40 PM Accepted by SEC EDGAR 08/19/2026 - 04:40 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	0002011703
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	Munro Douglas
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	548	54967.69	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			548	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
Douglas Munro 50 Minuteman Road Andover MA 01810	Common	08/17/2026	404	44420.17
Douglas Munro 50 Minuteman Road Andover MA 01810	Common	08/18/2026	494	55010.70

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/Wade Moss, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Douglas Munro
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)