그레이트 레이크 준설 및 도크 공사
US ˙ NasdaqGS ˙ US3906071093
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SecurityGLDD / Great Lakes Dredge & Dock Corporation
InstitutionRenaissance Technologies Llc
ManagerJames Simons
Latest Disclosed Ownership381,700 shares
Latest Disclosed Value $ 6,488,900
Renaissance Technologies Llc reports 47.49% increase in ownership of GLDD / Great Lakes Dredge & Dock Corporation

On May 14, 2026 - Renaissance Technologies Llc filed a 13F-HR form disclosing ownership of 381,700 shares of Great Lakes Dredge & Dock Corporation (US:GLDD) valued at $6,488,900 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 12, 2026 disclosing 258,791 shares of Great Lakes Dredge & Dock Corporation. This represents a change in shares of 47.49% during the quarter. The current value of the position is $6,488,900 USD.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

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Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date		 Effective
Date		Form Security Class ID Avg Price
Paid (Est)		 Reported
Shares		 ΔShares ΔShares
(%)		 Reported
Value
(x1000)		 ΔValue
(%)		 Alloc
(%)		 ΔAlloc ΔAlloc (%) Cost Basis
(x1000)		 Unrealized
Gain/Loss
(x1000)
2026-05-14 2026-03-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 381,700 122,909 47.49 6,489 91.10 0.0102
2026-02-12 2025-12-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 258,791 3,735 1.46 3,395 11.02 0.0053
2025-11-13 2025-09-30 13F GREAT LAKES DREDGE & DOCK COM 390607109 255,056 -129,332 -33.65 3,058 -34.73 0.0040
2025-08-13 2025-06-30 13F GREAT LAKES DREDGE & DOCK COM 390607109 384,388 267,988 230.23 4,686 362.94 0.0062
2025-05-14 2025-03-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 116,400 -162,201 -58.22 1,013 -67.82 0.0015
2025-02-13 2024-12-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 278,601 47,500 20.55 3,145 29.26 0.0047
2024-11-13 2024-09-30 13F GREAT LAKES DREDGE & DOCK COM 390607109 231,101 -94,500 -29.02 2,433 -14.87 0.0037
2024-08-09 2024-06-30 13F GREAT LAKES DREDGE & DOCK COM 390607109 325,601 -137,823 -29.74 2,859 71,350.00 0.0048
2024-05-13 2024-03-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 463,424 -200,677 -30.22 4 -20.00 0.0064
2024-02-13 2023-12-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 664,101 53,900 8.83 5 25.00 0.0079
2023-11-14 2023-09-30 13F GREAT LAKES DREDGE & DOCK COM 390607109 610,201 -119,600 -16.39 5 -20.00 0.0083
2023-08-11 2023-06-30 13F GREAT LAKES DREDGE & DOCK COM 390607109 729,801 -355,700 -32.77 6 0.00 0.0086
2023-05-12 2023-03-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 1,085,501 -174,034 -13.82 6 -28.57 0.0078
2023-02-13 2022-12-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 1,259,535 -21,266 -1.66 7 -99.93 0.0103
2022-11-14 2022-09-30 13F GREAT LAKES DREDGE & DOCK COM 390607109 1,280,801 -191,700 -13.02 9,708 -49.71 0.0137
2022-08-12 2022-06-30 13F GREAT LAKES DREDGE & DOCK COM 390607109 1,472,501 -18,700 -1.25 19,304 -7.73 0.0229
2022-05-13 2022-03-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 1,491,201 -48,500 -3.15 20,922 -13.56 0.0246
2022-02-11 2021-12-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 1,539,701 -84,500 -5.20 24,204 -1.24 0.0301
2021-11-12 2021-09-30 13F GREAT LAKES DREDGE & DOCK COM 390607109 1,624,201 -155,700 -8.75 24,509 -5.75 0.0317
2021-08-13 2021-06-30 13F GREAT LAKES DREDGE & DOCK COM 390607109 1,779,901 -369,765 -17.20 26,004 -17.03 0.0325
2021-05-13 2021-03-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 2,149,666 -174,735 -7.52 31,342 2.38 0.0390
2021-02-10 2020-12-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 2,324,401 -146,400 -5.93 30,612 30.28 0.0332
2020-11-13 2020-09-30 13F GREAT LAKES DREDGE & DOCK COM 390607109 2,470,801 -33,500 -1.34 23,497 1.32 0.0235
2020-08-13 2020-06-30 13F GREAT LAKES DREDGE & DOCK COM 390607109 2,504,301 -7,700 -0.31 23,190 11.22 0.0200
2020-05-14 2020-03-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 2,512,001 302,900 13.71 20,850 -16.70 0.0203
2020-02-13 2019-12-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 2,209,101 183,800 9.08 25,029 18.26 0.0192
2019-11-13 2019-09-30 13F GREAT LAKES DREDGE & DOCK COM 390607109 2,025,301 723,101 55.53 21,164 47.22 0.0179
2019-08-12 2019-06-30 13F GREAT LAKES DREDGE & DOCK COM 390607109 1,302,200 629,700 93.64 14,376 139.92 0.0127
2019-05-14 2019-03-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 672,500 383,100 132.38 5,992 212.73 0.0054
2019-02-12 2018-12-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 289,400 171,200 144.84 1,916 161.39 0.0021
2018-11-13 2018-09-30 13F GREAT LAKES DREDGE & DOCK COM 390607109 118,200 74,600 171.10 733 220.09 0.0008
2018-08-13 2018-06-30 13F/A-1 GREAT LAKES DREDGE & DOCK COM 390607109 43,600 1,500 3.56 229 18.04 0.0002
2018-08-13 2018-06-30 13F GREAT LAKES DREDGE & DOCK COM 390607109 42,100 194
2018-05-14 2018-03-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 42,100 -35,100 -45.47 194 -53.48 0.0002
2018-02-13 2017-12-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 77,200 77,200 83.37 417 114.95 0.0005
2017-05-12 2017-03-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 0 -79,263 -100.00 0 -100.00
2017-02-13 2016-12-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 79,263 25,063 46.24 333 75.26 0.0005
2016-11-14 2016-09-30 13F GREAT LAKES DREDGE & DOCK COM 390607109 54,200 26,500 95.67 190 57.02 0.0003
2016-08-12 2016-06-30 13F GREAT LAKES DREDGE & DOCK COM 390607109 27,700 27,700 -48.89 121 -36.32 0.0002
2016-02-11 2015-12-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 0 0 0 0.0000
2015-08-14 2015-06-30 13F GREAT LAKES DREDGE & DOCK COM 390607109 0 -207,900 -100.00 0 -100.00
2015-05-13 2015-03-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 207,900 12,800 6.56 1,249 -25.21 0.0027
2015-02-13 2014-12-31 13F GREAT LAKES DREDGE & DOCK COM 390607109 195,100 50,700 35.11 1,670 87.22 0.0040
2014-11-12 2014-09-30 13F GREAT LAKES DREDGE & DOCK COM 390607109 144,400 127,100 734.68 892 546.38 0.0024
2014-08-13 2014-06-30 13F GREAT LAKES DREDGE & DOCK COM 390607109 17,300 17,300 138 0.0003
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.