Great Lakes Dredge & Dock (GLDD) SVP discloses planned insider stock sale

Rhea-AI Filing Summary

Great Lakes Dredge & Dock Corp. executive Vivienne R. Schiffer, SVP-Project Acquisition & Ops, reported a sale of company stock. On 12/10/2025 she sold 2,100 shares of common stock at a weighted average price of $13.9564, with individual trades priced between $13.95 and $13.975. After this transaction she directly owns 91,963.2594 shares of Great Lakes Dredge & Dock common stock. The sale was executed under a Rule 10b5-1 trading plan adopted on August 18, 2025, providing for pre-arranged stock transactions.

Insider Trade Summary

Net Seller: 2,100 shares ($29,308)

Net Sell 1 txn

Insider JOHANSON DAVID

Role SVP-Project Acquisition & Ops

Sold 2,100 shs ($29K)

Type	Security	Shares	Price	Value
Sale	Common Stock	2,100	$13.9564	$29K

Holdings After Transaction: Common Stock — 91,963.259 shares (Direct)

Footnotes (1)

1. The sale reported in this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on August 18, 2025. Represents the weighted average price. The shares were sold in multiple transactions ranging from $13.95 to $13.975, inclusive. Upon request by the Commission staff, the issuer or security holder of the issuer, the reporting person will provide information regarding the number of shares disposed at each separate price.

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).

X

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^*

JOHANSON DAVID

(Last) (First) (Middle)

C/O GREAT LAKES DREDGE & DOCK CORP.

9811 KATY FREEWAY, SUITE 1200

(Street)

HOUSTON TX 77024

(City) (State) (Zip)

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-Project Acquisition & Ops

3. Date of Earliest Transaction (Month/Day/Year)
12/10/2025

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

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

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

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	12/10/2025		S		2,100(1)	D	$13.9564(2)	91,963.2594	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. The sale reported in this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on August 18, 2025.

2. Represents the weighted average price. The shares were sold in multiple transactions ranging from $13.95 to $13.975, inclusive. Upon request by the Commission staff, the issuer or security holder of the issuer, the reporting person will provide information regarding the number of shares disposed at each separate price.

	/s/Vivienne R. Schiffer, by Power of Attorney	12/12/2025
	** 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.

FAQ

What insider stock transaction did GLDD report for Great Lakes Dredge & Dock?

Great Lakes Dredge & Dock Corp. reported that Vivienne R. Schiffer sold 2,100 shares of the company’s common stock on 12/10/2025.

Who is the Great Lakes Dredge & Dock (GLDD) insider involved in this transaction?

The transaction involves Vivienne R. Schiffer, who serves as SVP-Project Acquisition & Ops at Great Lakes Dredge & Dock Corp.

At what price were the GLDD shares sold in this insider transaction?

The 2,100 GLDD shares were sold at a weighted average price of $13.9564, in multiple trades ranging from $13.95 to $13.975 per share.

How many GLDD shares does the executive still own after the sale?

Following the reported sale, Vivienne R. Schiffer directly owns 91,963.2594 shares of Great Lakes Dredge & Dock common stock.

Was the GLDD stock sale made under a Rule 10b5-1 trading plan?

Yes. The sale was effected under a Rule 10b5-1 trading plan that Vivienne R. Schiffer adopted on August 18, 2025.

Is this GLDD Form 4 filed by more than one reporting person?

No. The Form 4 indicates it is filed by one reporting person, covering the transactions of Vivienne R. Schiffer only.