W. R. Berkley Corporation

The full register, from 13F filings

The Register tab above is hand research: a dozen holders, each traced to the filing it came from. This asks the same question of the whole market for the quarter ended 31-mar-2026, where 911 managers reported a position. Broad where the research is deep, and shallow in the ways a 13F always is.

Built from 13F filings, which report US listed, long, US custodied positions only. A register from this source is a floor rather than a level: a holder's true position can be far larger, as BlackRock's ASML stake shows at 1.28m shares in a 13F against 26.3m in its 13G/A. Holdings held through derivatives, outside US custody, or below a manager's reporting obligation do not appear. Where a holder is marked as a family, its total sums several separate filing entities and describes something no single filing describes; the constituent entities and their share counts are listed so the total can be checked. That roll-up can legitimately exceed the family's own Schedule 13G, because a 13G is filed by one legal entity: Vanguard reports Alphabet through ten advisory entities, and The Vanguard Group Inc itself reported zero after its January 2026 disaggregation.

What a reader needs to know to read these numbers

• Stock split: WRB effected a 3-for-2 common stock split on 10 Jul 2024 (confirmed in the FY2025 10-K's basis-of-presentation note). All figures in this file come from 2026 filings and are already stated on the post-split basis; no restatement was needed.
• Capital Group was checked and holds nothing sizeable: all three primary registrants, Capital World Investors (CIK 0001422849), Capital International Investors (CIK 0001562230) and Capital Research Global Investors (CIK 0001422848), were searched in their own Q2 2026 13F-HR information tables (period 30 Jun 2026, filed 12 Aug 2026) for 'BERKLEY' and none has a matching row. An EDGAR full text search for CUSIP 084423102 across 13F-HR filings from 10-19 Aug 2026 returned 479 hits and did not surface any Capital Group entity among the results reviewed. No row is included for this holder per the brief's rule that a checked-and-zero holder is a note, not a null row.
• Register self-gate, computed on the final file exactly as the chart's own arithmetic (aggregate row reduced by the sum of shares in rows that name it via rolls_up_into; every other row, including a no-container aggregate, counted at full value): 10 rows, 245,664,256 total shares, 66.18% of shares_outstanding (371,227,529). Both William R. Berkley (90,998,374 sh) and W. Robert Berkley, Jr. (4,552,770 sh, already reduced, see his method_note) roll into the 97,785,593-share officers-and-directors aggregate, which the gate reduces to its residual of 2,234,449 shares; Mitsui Sumitomo (58,780,450 sh) stands alone with no container. This is above the 45-55% band the brief flags for a second look. The level is explained by two large, real, non-overlapping holders stacked on an ordinary institutional base: Mitsui Sumitomo Insurance Co., Ltd. (strategic, 15.8%, sourced to its own Jun 2026 Schedule 13D/A) plus the Berkley family (William R. Berkley individually plus the 97,785,593-share officers group he anchors). No double count was found between Mitsui and the family: Mitsui's Schedule 13D/A explicitly carves the Berkley family's 'Family Holdings' LLC out of its own 58,780,450-share total. The one double count that was found, between William R. Berkley's and W. Robert Berkley, Jr.'s individual rows both including the same 1,350,000-share family trust, was corrected by reducing Rob Berkley's shares field alone (see his method_note); doing so already lowered the self-gate total by 1,350,000 shares versus using the two as-filed figures unmodified. Corroborated first-hand by the coordinator, and the conclusion is that 66.18% is CONSERVATIVE rather than inflated. Two independent confirmations from this project's own 13F-derived register (data/registers/WRB.json, period 31 Mar 2026, built by a separate pipeline from the bulk 13F data): first, Mitsui Sumitomo Insurance Co Ltd appears there at 58,780,450 shares, EXACTLY the figure taken here from its own Schedule 13D/A, so the strategic stake is confirmed from two unrelated sources. Second, that snapshot's total institutional ownership is 229,717,208 shares, 61.88% of the same denominator; since that total INCLUDES Mitsui's 58,780,450, institutional ownership excluding Mitsui is 170,936,758 shares, 46.05%. The six institutional rows in this file sum to only 89,098,213 shares, 24.00%, so this register counts roughly half the institutional ownership that exists and still reaches 66.18%. The composition reconciles exactly: 97,785,593 insider (the officers container at full value, its two Berkley members drawn as their own slices and the container reduced to a 2,234,449 residual) plus 58,780,450 Mitsui plus 89,098,213 institutional equals 245,664,256. No double count exists between the two large blocks: Mitsui's own 13D expressly excludes the Berkley family holdings, and MS&AD Insurance Group Holdings co-files over the SAME shares while disclaiming beneficial ownership, which is why it correctly gets no row of its own.
• Company shares_outstanding (371,227,529) is taken from the Q2 2026 10-Q cover page ('Number of shares of common stock, $.20 par value, outstanding as of July 27, 2026: 371,227,529'), the freshest count found. Market cap uses this share count times a $70.17 close on 18 Aug 2026 sourced from a web search aggregator summary (stockanalysis.com), not a filing; basis for that one company-level figure is an aggregator estimate, not filed.