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
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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
1. Name and Address of Reporting Person *
BAYER RYAN

(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)
VP & CAO
3. Date of Earliest Transaction (Month/Day/Year)
04/01/2026
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 04/01/2026   A (1)   5,607 (1) A (1) 37,380 D  
Common Stock 04/01/2026   U   37,380 (2) (3) D (2) 0 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. Pursuant to the Merger Agreement (as defined in footnote 2 below), at the Effective Time (as defined in footnote 2 below), these performance-based restricted stock units fully vested, with the number earned or deemed earned as set forth in the Merger Agreement.
2. Pursuant to the Agreement and Plan of Merger (the "Merger Agreement"), dated February 10, 2026, by and among Saltchuk Resources, Inc. ("Parent"), Huron MergeCo, Inc. ("Merger Sub"), and Great Lakes Dredge & Dock Corporation ("Issuer") on April 1, 2026 (the "Effective Time"), Merger Sub merged with and into Issuer, with Issuer surviving as a wholly owned subsidiary of Parent upon consummation of the transactions contemplated by the Merger Agreement. At the Effective Time, each outstanding share of common stock of the Issuer ("Common Stock") was cancelled and converted into the right to receive $17.00 in cash (the "Merger Consideration"), without interest and subject to any required tax withholdings.
3. Includes 27,822 restricted stock units ("RSUs"). At the Effective Time, 20,899 outstanding RSUs were canceled and converted into the right to receive an amount in cash equal to the product of the aggregate number of shares of Common Stock underlying such RSUs immediately prior to the Effective Time, multiplied by the Merger Consideration, and 6,923 RSUs were replaced by a cash-based award of equivalent value (based on the Offer Price (as defined in the Merger Agreement)) that is subject to the same time-based vesting conditions as applied to the unvested portion of such award prior to the Effective Time.
/s/Vivienne R. Schiffer, by Power of Attorney 04/01/2026
** Signature of Reporting Person Date
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* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
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