Mercury Systems: Ballhaus plans $2.7M share sale

MERCURY SYSTEMS INC (MRCY) is named as the issuer in a notice of proposed Rule 144 sales by William L. Ballhaus, with Fidelity Brokerage Services LLC acting as broker and attorney-in-fact.

Rhea-AI Filing Summary

MERCURY SYSTEMS INC (MRCY) is named as the issuer in a notice of proposed Rule 144 sales by William L. Ballhaus, with Fidelity Brokerage Services LLC acting as broker and attorney-in-fact. The filing covers planned and recent sales of common stock, including shares received through restricted stock vesting and shares sold in part to satisfy tax obligations related to a vested equity award.

Key Figures

Shares covered by Rule 144 notice: 26,802 shares Aggregate market value of shares in notice: $2,688,401.42 Shares outstanding of class: 60,136,133 shares +4 more

7 metrics

Shares covered by Rule 144 notice 26,802 shares Common stock entry with Fidelity Brokerage Services LLC for MERCURY SYSTEMS INC

Aggregate market value of shares in notice $2,688,401.42 Value associated with 26,802 MERCURY SYSTEMS INC common shares

Shares outstanding of class 60,136,133 shares Outstanding MERCURY SYSTEMS INC common stock as listed in the notice dated 08/19/2026

Sale on 08/17/2026 3,536 shares; $388,786.39 Common stock sold for William L. Ballhaus during prior three months

Sale on 08/18/2026 24,144 shares; $2,688,620.31 Common stock sold for William L. Ballhaus during prior three months

Shares acquired via compensation vesting 26,802 shares Restricted stock vesting from issuer on 08/18/2026 as compensation

Notice date 08/19/2026 Date of Rule 144 notice for proposed sale of MERCURY SYSTEMS INC common stock

Key Terms

Rule 144, restricted stock vesting, attorney-in-fact, vested equity award distribution

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 attorney-in-fact for William L. Ballhaus"

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.

vested equity award distribution financial

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

FAQ

Who is selling MERCURY SYSTEMS INC (MRCY) shares in this Form 144 notice?

The notice reports planned sales of MERCURY SYSTEMS INC common stock for the account of William L. Ballhaus, with Fidelity Brokerage Services LLC acting as broker and attorney-in-fact under Rule 144.

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

The filing lists 26,802 shares of MERCURY SYSTEMS INC common stock associated with this Rule 144 notice, with an aggregate market value of $2,688,401.42 and 60,136,133 shares of the class outstanding as of 08/19/2026.

What MRCY share sales occurred in the past three months for this holder?

The notice reports sales of 3,536 shares of MERCURY SYSTEMS INC common stock for $388,786.39 on 08/17/2026, and 24,144 shares for $2,688,620.31 on 08/18/2026.

What is the source of the MRCY shares being sold under this Form 144?

The common stock relates to restricted stock vesting on 08/18/2026, with 26,802 shares acquired as compensation from the issuer and then included in the Rule 144 notice.

Does the MRCY Form 144 mention taxes related to the stock sale?

Yes. The remarks state the sale includes an amount necessary to cover a tax obligation resulting from the settlement of a vested equity award distribution, indicating part of the sale proceeds address tax liabilities.

Who signed the MRCY Form 144 notice on behalf of the seller?

The notice is signed by /s/ Jennifer Ruchti as a duly authorized representative of Fidelity Brokerage Services LLC, acting as attorney-in-fact for William L. Ballhaus in connection with the Rule 144 sale.

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

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Available on EDGAR 08/19/2026 - 04:51 PM Accepted by SEC EDGAR 08/19/2026 - 04:50 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	0001436044
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	Ballhaus William L
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
Relationship to Issuer	Director

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	26802	2688401.42	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			26802	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
William L. Ballhaus 50 Minuteman Road Andover MA 01810	Common	08/17/2026	3536	388786.39
William L. Ballhaus 50 Minuteman Road Andover MA 01810	Common	08/18/2026	24144	2688620.31

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 William L. Ballhaus
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)