Great Lakes Dredge (NASDAQ: GLDD) SVP tenders 144,817 shares at $17 cash

Rhea-AI Filing Summary

Great Lakes Dredge & Dock Corporation SVP, CLO, CCO & Corporate Secretary Vivienne Schiffer reported equity changes tied to the company’s merger with Saltchuk Resources. On April 1, 2026, she acquired 28,945 shares of common stock at $0.00 per share through a grant or award, reflecting the vesting of performance-based restricted stock units under the merger terms.

That same day, 144,817 common shares held directly were disposed of in a tender-offer transaction, leaving her with 0 directly owned shares after the merger closed. Under the merger agreement, each Great Lakes share was cancelled and converted into the right to receive $17.00 in cash.

The filing notes prior holdings included 71,357 restricted stock units. At the effective time, 52,855 RSUs were cancelled for a cash payment based on the $17.00 merger consideration, while 18,502 RSUs were replaced with a cash-based award of equivalent value that keeps the original time-based vesting schedule.

Insider Trade Summary

2 transactions reported

Mixed 2 txns

Insider Schiffer Vivienne

Role SVP, CLO, CCO & Corp Secretary

Type	Security	Shares	Price	Value
Grant/Award	Common Stock	28,945	$0.00	--
U	Common Stock	144,817	$0.00	--

Holdings After Transaction: Common Stock — 144,817 shares (Direct)

Footnotes (1)

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. 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. Includes 71,357 restricted stock units ("RSUs"). At the Effective Time, 52,855 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 18,502 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.

Key Figures

Share award: 28,945 shares Shares tendered: 144,817 shares Merger consideration: $17.00 per share +4 more

7 metrics

Share award 28,945 shares Common stock granted on April 1, 2026 at $0.00 per share

Shares tendered 144,817 shares Common stock disposed in tender offer on April 1, 2026

Merger consideration $17.00 per share Cash paid for each Great Lakes common share at effective time

RSUs included 71,357 RSUs Total restricted stock units referenced in footnote F3

RSUs cashed out 52,855 RSUs Converted into cash based on $17.00 merger consideration

RSUs converted to cash-based award 18,502 RSUs equivalent Replaced by cash-based award with same time-based vesting

Post-transaction direct holdings 0 shares Direct common stock holdings following tender-offer disposition

Key Terms

performance-based restricted stock units, Merger Agreement, Merger Consideration, restricted stock units ("RSUs"), +1 more

5 terms

performance-based restricted stock units financial

"these performance-based restricted stock units fully vested, with the number earned or deemed earned"

Performance-based restricted stock units are a type of employee equity award that converts into company shares only if predefined financial or operational targets are met over a set period. Think of it like a bonus check that becomes stock only when specific goals are hit; it ties pay to results, aligning managers’ incentives with shareholders. Investors care because these awards affect future share count, executive incentives, and signal how management’s success will be measured and rewarded.

Merger Agreement regulatory

"Pursuant to the Agreement and Plan of Merger (the "Merger Agreement"), dated February 10, 2026"

A merger agreement is a binding contract that lays out the exact terms for two companies to combine, including the price, what each side will deliver, and the conditions that must be met before the deal is completed. Investors care because it sets the timetable, payouts and risks — like a blueprint or prenup that shows whether the deal is likely to close, how ownership will change, and what could cancel or alter the payout they expect.

Merger Consideration financial

"converted into the right to receive $17.00 in cash (the "Merger Consideration")"

Merger consideration is the total payment a company or buyer offers to shareholders of a target company in exchange for combining the two businesses, and can include cash, shares in the surviving company, debt assumption, or a mix of these. Investors care because the form and amount affect the deal’s value, tax consequences, immediate cash received versus future ownership, and the risk and upside of holding new shares — similar to choosing between cash now or stock that could grow later.

restricted stock units ("RSUs") financial

"Includes 71,357 restricted stock units ("RSUs"). At the Effective Time, 52,855 outstanding RSUs were canceled"

Restricted stock units (RSUs) are a company promise to give an employee shares of stock (or cash equivalent) in the future, but only after certain conditions—usually staying with the company for a set time or hitting performance goals—are met. Investors watch RSUs because when they vest they increase the number of shares outstanding and can lead insiders to sell shares, affecting share price, company dilution and the true cost of employee pay.

cash-based award financial

"18,502 RSUs were replaced by a cash-based award of equivalent value"

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
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hours per response:			0.5

X

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)
04/01/2026

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	04/01/2026		A(1)		28,945(1)	A	(1)	144,817	D
Common Stock	04/01/2026		U		144,817(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 71,357 restricted stock units ("RSUs"). At the Effective Time, 52,855 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 18,502 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.

	Vivienne R. Schiffer	04/01/2026
	** 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 insider transactions did GLDD executive Vivienne Schiffer report?

Vivienne Schiffer reported receiving 28,945 Great Lakes Dredge & Dock common shares as a stock award, then tendering 144,817 shares in the merger-related offer. These transactions reflect compensation vesting and cash-out of equity as the company became a Saltchuk subsidiary.

What price did GLDD shareholders receive in the Saltchuk merger?

Each Great Lakes Dredge & Dock common share was cancelled and converted into the right to receive $17.00 in cash. This fixed merger consideration applied to outstanding shares and to cash amounts calculated for certain restricted stock units at the effective time.

How many GLDD shares did Vivienne Schiffer tender in the merger offer?

Vivienne Schiffer tendered 144,817 Great Lakes Dredge & Dock common shares in a disposition classified as pursuant to a tender offer. After this transaction, her directly owned common stock position reported in the filing was reduced to zero shares.

What happened to Vivienne Schiffer’s GLDD restricted stock units in the merger?

Her holdings included 71,357 restricted stock units. At closing, 52,855 RSUs were cancelled for a cash payment based on the $17.00 merger consideration, while 18,502 RSUs were converted into a cash-based award with the same time-based vesting terms as before.

How did the merger affect Vivienne Schiffer’s direct GLDD share ownership?

Following an award of 28,945 shares and the tender of 144,817 shares, Vivienne Schiffer’s directly owned Great Lakes Dredge & Dock common stock balance reported in the Form 4 became zero. Her remaining exposure comes from a cash-based award that replaced certain restricted stock units.