W. R. Berkley Corporation
MX ˙ BMV ˙ US0844231029
SecurityMX:WRB / W. R. Berkley Corporation
InstitutionMarshall Wace, Llp
Latest Disclosed Ownership31,635 shares
Latest Disclosed Value $ 2,096,768
Marshall Wace, Llp reports 647.34% increase in ownership of WRB / W. R. Berkley Corporation

On May 14, 2026 - Marshall Wace, Llp filed a 13F-HR form disclosing ownership of 31,635 shares of W. R. Berkley Corporation (MX:WRB) valued at $2,096,768 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 4,233 shares of W. R. Berkley Corporation. This represents a change in shares of 647.34% during the quarter.

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 WR BERKLEY COMMON STOCK 084423102 31,635 27,402 647.34 2,097 608.11 0.0010
2026-02-13 2025-12-31 13F WR BERKLEY COMMON STOCK 084423102 4,233 -1,812 -29.98 297 -36.07 0.0003
2025-11-13 2025-09-30 13F WR BERKLEY COMMON STOCK 084423102 6,045 -172,700 -96.62 463 -96.47 0.0005
2025-08-13 2025-06-30 13F WR BERKLEY COMMON STOCK 084423102 178,745 -564,895 -75.96 13,132 -75.18 0.0148
2025-05-15 2025-03-31 13F WR BERKLEY COMMON STOCK 084423102 743,640 632,905 571.55 52,917 716.62 0.0672
2025-02-13 2024-12-31 13F WR BERKLEY COMMON STOCK 084423102 110,735 83,540 307.19 6,480 320.23 0.0078
2024-11-14 2024-09-30 13F WR BERKLEY COMMON STOCK 084423102 27,195 -2,458 -8.29 1,543 -33.82 0.0019
2024-08-14 2024-06-30 13F WR BERKLEY COMMON STOCK 084423102 29,653 29,653 2,330 0.0031
2023-11-14 2023-09-30 13F WR BERKLEY COMMON STOCK 084423102 0 -124,750 -100.00 0 -100.00
2023-08-14 2023-06-30 13F WR BERKLEY COMMON STOCK 084423102 124,750 124,750 7,430 0.0145
2022-11-14 2022-09-30 13F WR BERKLEY COMMON STOCK 084423102 0 -309,811 -100.00 0 -100.00
2022-08-15 2022-06-30 13F WR BERKLEY COMMON STOCK 084423102 309,811 309,811 21,148 0.0435
2022-05-16 2022-03-31 13F WR BERKLEY COMMON STOCK 084423102 0 -14,454 -100.00 0 -100.00
2022-02-14 2021-12-31 13F WR BERKLEY COMMON STOCK 084423102 14,454 14,454 1,191 0.0022
2021-05-17 2021-03-31 13F WR BERKLEY COMMON STOCK 084423102 0 -36,660 -100.00 0 -100.00
2021-02-16 2020-12-31 13F WR BERKLEY COMMON STOCK 084423102 36,660 36,660 2,435 0.0132
2020-05-15 2020-03-31 13F WR BERKLEY COMMON STOCK 084423102 0 -33,413 -100.00 0 -100.00
2020-02-14 2019-12-31 13F WR BERKLEY COMMON STOCK 084423102 33,413 33,413 2,309 0.0159
2019-05-14 2019-03-31 13F WR BERKLEY COMMON STOCK 084423102 0 -1,333 -100.00 0 -100.00
2019-02-14 2018-12-31 13F WR BERKLEY COMMON STOCK 084423102 1,333 1,333 99 0.0010
2016-08-12 2016-06-30 13F WR BERKLEY COMMON STOCK 084423102 0 -108,099 -100.00 0 -100.00
2016-05-13 2016-03-31 13F WR BERKLEY COMMON STOCK 084423102 108,099 39,694 58.03 6,075 62.22 0.0585
2016-02-10 2015-12-31 13F WR BERKLEY COMMON STOCK 084423102 68,405 -291,566 -81.00 3,745 -80.87 0.0351
2015-11-12 2015-09-30 13F WR BERKLEY COMMON STOCK 084423102 359,971 359,971 0.00 19,572 0.2405
2014-11-13 2014-09-30 13F WR BERKLEY COMMON STOCK 084423102 0 -355,296 -100.00 0 -100.00
2014-08-14 2014-06-30 13F WR BERKLEY COMMON STOCK 084423102 355,296 290,938 452.06 16,454 514.18 0.2422
2014-05-14 2014-03-31 13F WR BERKLEY COMMON STOCK 084423102 64,358 64,358 2,679 0.0487
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.