Who owns WHITE MOUNTAINS INSURANCE GROUP LTD?
Prices and market caps: Cboe delayed data, at least 15 minutes delayed. Not real-time. Fundamentals from company filings.
Institutional ownership of WTM from SEC Form 13F filings across 358 reporting managers. All positions are from one synchronized reporting period — 2026-06-30 books, filed up to 45 days after quarter end — so every row is comparable.
As of the 2026-06-30 reporting period, 358 institutions disclosed 2.2M shares of WHITE MOUNTAINS INSURANCE GROUP LTD worth $4.57B — about 93.5% of shares outstanding; the largest disclosed holder is DIMENSIONAL FUND ADVISORS LP. Source: SEC Form 13F filings, parsed by EvidInvest.
358
13F holders
$4.57B
value, 2026 filers
93.5%
of shares outstanding (2.2M sh)
46
new positions (2026 filers)
Top institutional holders
ordered by shares owned · positions as of 2026-06-30 · % of fund = share of the manager's own book · % of co. = share of WTM's shares outstanding
| # | Manager | Shares | Value | % of fund | % of co. | Δ shares QoQ |
|---|---|---|---|---|---|---|
| 1 | DIMENSIONAL FUND ADVISORS LP | 158,954 | $329.6M | 0.1% | 6.7% | +1.5% |
| 2 | NEUBERGER BERMAN GROUP LLC | 119,141 | $247.0M | 0.2% | 5.1% | -4.5% |
| 3 | BlackRock, Inc. | 117,871 | $244.4M | 0.0% | 5% | +4.0% |
| 4 | River Road Asset Management, LLC | 115,880 | $240.3M | 2.7% | 4.9% | -3.8% |
| 5 | VANGUARD PORTFOLIO MANAGEMENT LLC | 111,969 | $232.2M | 0.0% | 4.8% | -3.1% |
| 6 | VANGUARD CAPITAL MANAGEMENT LLC | 107,479 | $222.8M | 0.0% | 4.6% | -1.5% |
| 7 | FULLER & THALER ASSET MANAGEMENT, INC. | 101,892 | $211.3M | 0.6% | 4.3% | -2.6% |
| 8 | COOKE & BIELER LP | 85,120 | $176.5M | 2.0% | 3.6% | -18.8% |
| 9 | Wallace Capital Management Inc. | 80,067 | $166.0M | 18.2% | 3.4% | +1.6% |
| 10 | FIDUCIARY MANAGEMENT INC /WI/ | 66,550 | $138.0M | 2.0% | 2.8% | -21.8% |
| 11 | GENDELL JEFFREY L | 59,243 | $122.8M | 1.1% | 2.5% | +56.7% |
| 12 | Boston Partners | 55,569 | $115.3M | 0.1% | 2.4% | -3.3% |
| 13 | LONDON CO OF VIRGINIA | 54,025 | $112.1M | 0.6% | 2.3% | -5.4% |
| 14 | STATE STREET CORP | 50,257 | $104.2M | 0.0% | 2.1% | +2.2% |
| 15 | GEODE CAPITAL MANAGEMENT, LLC | 49,412 | $102.5M | 0.0% | 2.1% | +17.3% |
| 16 | MORGAN STANLEY | 46,866 | $97.2M | 0.0% | 2% | -21.0% |
| 17 | REINHART PARTNERS, LLC. | 44,480 | $92.3M | 2.1% | 1.9% | +19.0% |
| 18 | T. Rowe Price Investment Management, Inc. | 34,237 | $71.0M | 0.0% | 1.5% | -17.5% |
| 19 | LORD, ABBETT & CO. LLC | 32,829 | $68.1M | 0.2% | 1.4% | -0.8% |
| 20 | AMERICAN CENTURY COMPANIES INC | 31,108 | $64.5M | 0.0% | 1.3% | +274.4% |
| 21 | NORGES BANKNEW | 27,956 | $58.0M | 0.0% | 1.2% | new |
| 22 | Cannell & Spears LLC | 27,577 | $57.2M | 1.0% | 1.2% | -1.6% |
| 23 | BANK OF AMERICA CORP /DE/ | 25,028 | $51.9M | 0.0% | 1.1% | -11.7% |
| 24 | CHARLES SCHWAB INVESTMENT MANAGEMENT INC | 23,505 | $48.7M | 0.0% | 1% | -3.0% |
| 25 | Mraz, Amerine & Associates, Inc. | 22,218 | $46.1M | 6.6% | 0.9% | +0.2% |
Source: SEC Form 13F-HR filings (institutional managers over $100M in US-listed positions). 13Fs disclose long positions only, up to 45 days after quarter end; each manager's latest filed quarter is shown per row and dollar values are the manager's filed marks. Aggregates labeled "2026 filers" count only managers whose latest book is a 2026 quarter. Related: valuation · options positioning · supply chain. Research, not investment advice.