X0508 4 2024-11-11 0001372020 Great Lakes Dredge & Dock CORP GLDD 0001292085 Shanahan Kathleen M C/O GREAT LAKES DREDGE & DOCK CORP. 9811 KATY FREEWAY, SUITE 1200 HOUSTON TX 77024 true false false false false Common Stock 2024-11-11 4 S false 23238 12.632 D 67675 D Represents the weighted average price. The shares were sold in multiple transactions ranging from $12.62 to $12.66, 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 2024-11-12