Mercury Systems insider plans $4.37M stock sale

MERCURY SYSTEMS INC (MRCY) is the issuer for which William L. Ballhaus filed a Rule 144 notice to sell common stock.

Rhea-AI Filing Summary

MERCURY SYSTEMS INC (MRCY) is the issuer for which William L. Ballhaus filed a Rule 144 notice to sell common stock. The filing covers 49,090 shares of common stock, with an aggregate market value of $4,373,744.65, relative to 60,136,133 shares outstanding as of 08/26/2026. The shares are to be sold through Fidelity Brokerage Services LLC and arise from a stock option exercise categorized as compensation. The notice also lists multiple prior open-market sales by Ballhaus over the past three months, including 108,209 shares on 08/24/2026 and 111,076 shares on 08/25/2026.

Key Figures

Shares to be sold: 49,090 shares of common stock Aggregate market value of shares to be sold: $4,373,744.65 Shares outstanding: 60,136,133 shares +3 more

6 metrics

Shares to be sold 49,090 shares of common stock Covered by the Rule 144 notice for Mercury Systems Inc

Aggregate market value of shares to be sold $4,373,744.65 Value of 49,090 Mercury Systems Inc common shares in the Rule 144 filing

Shares outstanding 60,136,133 shares Mercury Systems Inc common stock outstanding as of 08/26/2026

Single-day sale on 08/24/2026 108,209 shares for $9,684,881.49 Past 3 months sales section for William L. Ballhaus

Single-day sale on 08/25/2026 111,076 shares for $9,676,607.89 Past 3 months sales section for William L. Ballhaus

Planned sale date 08/26/2026 Date for the Rule 144 covered transaction and outstanding share count

Key Terms

Rule 144, Stock Option Exercise, attorney-in-fact, aggregate market value

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.

Stock Option Exercise financial

"Common | 08/26/2026 | 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 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.

aggregate market value financial

"Common | ... | 49090 | 4373744.65 | 60136133 | 08/26/2026"

Aggregate market value is the combined price you would pay to buy all outstanding shares of a company or all companies in a group at current market prices — essentially the sum of each stock’s market capitalization. It matters to investors because it shows the overall size and weight of an investment or sector (like the total cost to buy every piece of a puzzle), helps compare scale across companies or markets, and influences index composition and risk exposure.

FAQ

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

What does the Form 144 filing for MRCY disclose about William L. Ballhaus’s planned sale?

The notice states that 49,090 shares of Mercury Systems Inc common stock may be sold for the account of William L. Ballhaus. The planned sale is through Fidelity Brokerage Services LLC under Rule 144 and is tied to a stock option exercise classified as compensation.

What is the approximate market value of the MRCY shares covered by this Form 144?

The filing lists an aggregate market value of $4,373,744.65 for the 49,090 Mercury Systems Inc common shares covered by the notice. This figure reflects the market value used for the Rule 144 disclosure as of 08/26/2026.

How many MRCY shares were outstanding relative to the planned Rule 144 sale?

The filing reports that 60,136,133 shares of Mercury Systems Inc common stock were outstanding as of 08/26/2026. The 49,090 shares covered by the Form 144 notice are measured against this outstanding share count in the disclosure.

What recent sales of MRCY stock by William L. Ballhaus are disclosed in the past 3 months section?

The notice lists several sales of Mercury Systems Inc common stock by William L. Ballhaus, including 108,209 shares for $9,684,881.49 on 08/24/2026 and 111,076 shares for $9,676,607.89 on 08/25/2026, among other transactions during that three-month period.

What is the nature of the MRCY securities to be sold under this Form 144?

The securities are common stock of Mercury Systems Inc. They are to be sold on 08/26/2026 and are described as arising from a Stock Option Exercise with the transaction type labeled as Compensation and the issuer listed as the counterparty.

Who is executing the planned MRCY share sale on behalf of William L. Ballhaus?

The filing identifies Fidelity Brokerage Services LLC as the broker for the Mercury Systems Inc common stock. The notice is signed by /s/ Daniel Tucci, a duly authorized representative of Fidelity, acting as attorney-in-fact for William Ballhaus.

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

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Available on EDGAR 08/26/2026 - 04:20 PM EDT Accepted by SEC EDGAR 08/26/2026 - 04:20 PM EDT 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	49090	4373744.65	60136133	08/26/2026	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	08/26/2026	Stock Option Exercise	Issuer			49090	08/26/2026	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 Ballhaus 50 Minuteman Road Andover MA 01810	Common	08/17/2026	3536	388786.39
William Ballhaus 50 Minuteman Road Andover MA 01810	Common	08/18/2026	24144	2688620.31
William Ballhaus 50 Minuteman Road Andover MA 01810	Common	08/19/2026	26802	2688401.42
William Ballhaus 50 Minuteman Road Andover MA 01810	Common	08/20/2026	22010	2149791.54
William Ballhaus 50 Minuteman Road Andover MA 01810	Common	08/21/2026	65000	6006465.86
William Ballhaus 50 Minuteman Road Andover MA 01810	Common	08/24/2026	108209	9684881.49
William Ballhaus 50 Minuteman Road Andover MA 01810	Common	08/25/2026	111076	9676607.89

144: Remarks and Signature

Remarks
Date of Notice	08/26/2026
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)