Great Lakes Dredge & Dock (GLDD) SVP reports stock awards and tax withholding

Rhea-AI Filing Summary

Great Lakes Dredge & Dock Corp’s SVP, Chief Legal Officer, Chief Compliance Officer and Corporate Secretary Vivienne Schiffer reported routine equity compensation activity in company common stock. On March 16, 2026, she received two stock awards of 14,213 and 10,454 shares, granted at no purchase price, following the satisfaction of performance conditions on performance-based restricted stock units granted in March 2023 and March 2024.

To cover tax obligations, a total of 10,125 shares were disposed of through tax-withholding transactions at $16.93 per share, which are not open-market sales. After these awards and related withholdings, Schiffer directly owned 115,872 shares of Great Lakes Dredge & Dock Corp common stock.

Insider Trade Summary

6 transactions reported

Mixed 6 txns

Insider Schiffer Vivienne

Role SVP, CLO, CCO & Corp Secretary

Type	Security	Shares	Price	Value
Tax Withholding	Common Stock	2,060	$16.93	$35K
Grant/Award	Common Stock	14,213	$0.00	--
Tax Withholding	Common Stock	3,461	$16.93	$59K
Tax Withholding	Common Stock	2,058	$16.93	$35K
Grant/Award	Common Stock	10,454	$0.00	--
Tax Withholding	Common Stock	2,546	$16.93	$43K

Holdings After Transaction: Common Stock — 99,270 shares (Direct)

Footnotes (1)

1. Represents shares awarded pursuant to satisfaction of performance conditions per the terms of Ms. Schiffer's performance-based restricted stock units granted on March 15, 2023. Represents shares awarded pursuant to satisfaction of performance conditions per the terms of Ms. Schiffer's performance-based restricted stock units granted on March 15, 2024.

Form 4 Insider Transactions: What Each Field Means →

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Schiffer Vivienne

(Last) (First) (Middle)

C/O GREAT LAKES DREDGE & DOCK CORP.

9811 KATY FREEWAY, SUITE 1200

(Street)

HOUSTON TEXAS 77024

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Great Lakes Dredge & Dock CORP [ GLDD ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	SVP, CLO, CCO & Corp Secretary

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
03/16/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	03/16/2026		F		2,060	D	$16.93	99,270	D
Common Stock	03/16/2026		A		14,213	A	(1)	113,483	D
Common Stock	03/16/2026		F		3,461	D	$16.93	110,022	D
Common Stock	03/16/2026		F		2,058	D	$16.93	107,964	D
Common Stock	03/16/2026		A		10,454	A	(2)	118,418	D
Common Stock	03/16/2026		F		2,546	D	$16.93	115,872	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. Represents shares awarded pursuant to satisfaction of performance conditions per the terms of Ms. Schiffer's performance-based restricted stock units granted on March 15, 2023.

2. Represents shares awarded pursuant to satisfaction of performance conditions per the terms of Ms. Schiffer's performance-based restricted stock units granted on March 15, 2024.

	/s/Vivienne R. Schiffer	03/18/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)

FAQ

What did GLDD executive Vivienne Schiffer report in this Form 4 filing?

Vivienne Schiffer reported routine equity compensation activity. She received two stock awards of 14,213 and 10,454 GLDD common shares and had 10,125 shares withheld to cover taxes, all on March 16, 2026.

How many Great Lakes Dredge & Dock (GLDD) shares were granted to Vivienne Schiffer?

She was granted 14,213 and 10,454 GLDD common shares. These awards resulted from meeting performance conditions on performance-based restricted stock units originally granted in March 2023 and March 2024 under company compensation plans.

Why were some of Vivienne Schiffer’s GLDD shares disposed of in this Form 4?

A total of 10,125 GLDD shares were disposed of to satisfy tax liabilities. These F-code transactions reflect shares withheld by the issuer at $16.93 per share, rather than open-market sales initiated by Schiffer.

What is the significance of the performance-based RSUs mentioned for GLDD’s Vivienne Schiffer?

The filing explains that shares were awarded after performance conditions were satisfied on performance-based restricted stock units. These RSUs were originally granted on March 15, 2023 and March 15, 2024, tying equity compensation to company performance goals.

How many GLDD shares does Vivienne Schiffer own after these transactions?

Following the reported grants and tax-withholding dispositions, Vivienne Schiffer directly owns 115,872 shares of Great Lakes Dredge & Dock Corp common stock. This figure reflects her updated post-transaction ownership position as reported in the Form 4.

Were any of Vivienne Schiffer’s GLDD transactions open-market buys or sells?

No open-market buys or sells were reported. The Form 4 shows stock grants at no purchase price and F-code tax-withholding dispositions, where shares were delivered to cover tax obligations rather than sold in the market.