Mercury Systems' Ballhaus plans $6.0M stock sale

MERCURY SYSTEMS INC (MRCY) received a Rule 144 notice relating to proposed sales of its common stock for the account of William L. Ballhaus.

Rhea-AI Filing Summary

MERCURY SYSTEMS INC (MRCY) received a Rule 144 notice relating to proposed sales of its common stock for the account of William L. Ballhaus. The notice covers up to 65,000 shares to be sold through Fidelity Brokerage Services LLC following a stock option exercise on 08/21/2026 for cash.

The notice also lists Ballhaus’s sales of MERCURY SYSTEMS INC common stock during the prior three months: 3,536 shares on 08/17/2026 for $388,786.39, 24,144 shares on 08/18/2026 for $2,688,620.31, 26,802 shares on 08/19/2026 for $2,688,401.42, and 22,010 shares on 08/20/2026 for $2,149,791.54. MERCURY SYSTEMS INC common stock is listed on NASDAQ.

Key Figures

Shares proposed for sale under Rule 144: 65,000 shares Aggregate market value of securities to be sold: $6,006,464.08 MERCURY SYSTEMS INC common shares outstanding: 60,136,133 shares +5 more

8 metrics

Shares proposed for sale under Rule 144 65,000 shares Common stock of MERCURY SYSTEMS INC to be sold for the account of William L. Ballhaus

Aggregate market value of securities to be sold $6,006,464.08 Value associated with 65,000 MERCURY SYSTEMS INC common shares in the securities information section

MERCURY SYSTEMS INC common shares outstanding 60,136,133 shares Securities information section for MERCURY SYSTEMS INC common stock

Shares sold on 08/17/2026 3,536 shares Common stock of MERCURY SYSTEMS INC sold by William L. Ballhaus for $388,786.39

Proceeds on 08/17/2026 sale $388,786.39 Sale of 3,536 MERCURY SYSTEMS INC common shares by William L. Ballhaus

Shares sold on 08/18/2026 24,144 shares Common stock of MERCURY SYSTEMS INC sold by William L. Ballhaus for $2,688,620.31

Shares sold on 08/19/2026 26,802 shares Common stock of MERCURY SYSTEMS INC sold by William L. Ballhaus for $2,688,401.42

Shares sold on 08/20/2026 22,010 shares Common stock of MERCURY SYSTEMS INC sold by William L. Ballhaus for $2,149,791.54

Key Terms

Rule 144, stock option exercise, attorney-in-fact

3 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.

stock option exercise financial

"Common | 08/21/2026 | Stock Option Exercise | Issuer"

A stock option exercise is the act of using a previously granted right to buy shares of a company's stock at a specific, predetermined price by paying that price and receiving the shares. It matters to investors because exercising changes who owns the shares (which can dilute existing ownership), can trigger taxable events and shift potential gains or losses, and affects voting power and the company’s outstanding share count—like turning a voucher into an actual product that becomes part of circulating supply.

attorney-in-fact regulatory

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

FAQ

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

It discloses that William L. Ballhaus has filed a notice under Rule 144 to sell up to 65,000 shares of MERCURY SYSTEMS INC common stock, in connection with a stock option exercise dated 08/21/2026, using cash to exercise the options.

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

The notice covers a proposed sale of up to 65,000 shares of MERCURY SYSTEMS INC common stock. These shares are associated with a stock option exercise on 08/21/2026 and are to be sold through Fidelity Brokerage Services LLC on NASDAQ.

What MRCY shares did William L. Ballhaus sell in the past three months?

The notice lists four sales of MERCURY SYSTEMS INC common stock by William L. Ballhaus: 3,536 shares for $388,786.39 on 08/17/2026, 24,144 shares for $2,688,620.31 on 08/18/2026, 26,802 shares for $2,688,401.42 on 08/19/2026, and 22,010 shares for $2,149,791.54 on 08/20/2026.

Who is selling MRCY shares under this Form 144 notice?

The notice is for sales of MERCURY SYSTEMS INC common stock for the account of William L. Ballhaus. The document is signed by Daniel Tucci as a duly authorized representative of Fidelity Brokerage Services LLC, acting as attorney-in-fact for Ballhaus.

What is the role of Fidelity Brokerage Services LLC in the MRCY Form 144?

Fidelity Brokerage Services LLC is listed as the broker for the MERCURY SYSTEMS INC common stock to be sold. The Form 144 is signed “/s/ Daniel Tucci, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for William Ballhaus.”

How many MERCURY SYSTEMS INC common shares are outstanding as referenced in this notice?

The notice references 60,136,133 shares of MERCURY SYSTEMS INC common stock outstanding in the securities information section, providing context for the 65,000 shares proposed to be sold under Rule 144.

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

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Available on EDGAR 08/21/2026 - 02:13 PM Accepted by SEC EDGAR 08/21/2026 - 02:12 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	65000	6006464.08	60136133	08/21/2026	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	08/21/2026	Stock Option Exercise	Issuer			65000	08/21/2026	Cash

* 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
William L. Ballhaus 50 Minuteman Road Andover MA 01810	Common	08/19/2026	26802	2688401.42
William L. Ballhaus 50 Minuteman Road Andover MA 01810	Common	08/20/2026	22010	2149791.54

144: Remarks and Signature

Remarks
Date of Notice	08/21/2026
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/ Daniel Tucci, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for William Ballhaus
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)