WTM White Mountains Insurance Group, Ltd.
White Mountains Insurance Group, Ltd. (WTM) Institutional Ownership
What the institutions did with WTM last quarter, from their 13F filings. Counting managers rather than shares is the point: a single index fund adding to a position tells you far less than four hundred separate managers all deciding to. Positions as reported for the quarter ended June 30, 2026.
Every manager below opens. Subscribers can see any firm's whole portfolio — every position, its weight, and what they bought, trimmed and exited last quarter.
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Each block is one manager, sized by shares held and colored by how much they moved the position last quarter. Green added, red cut, grey stood pat.
Largest holders
| Manager | Shares | % of reported |
|---|---|---|
| DIMENSIONAL FUND ADVISORS LP | 159.0K | 7.2% |
| NEUBERGER BERMAN GROUP LLC | 119.1K | 5.4% |
| BlackRock, Inc. | 117.9K | 5.4% |
| River Road Asset Management, LLC | 115.9K | 5.3% |
| VANGUARD PORTFOLIO MANAGEMENT LLC | 112.0K | 5.1% |
| VANGUARD CAPITAL MANAGEMENT LLC | 107.5K | 4.9% |
| FULLER & THALER ASSET MANAGEMENT, INC. | 101.9K | 4.6% |
| COOKE & BIELER LP | 85.1K | 3.9% |
| Wallace Capital Management Inc. | 80.1K | 3.6% |
| FIDUCIARY MANAGEMENT INC /WI/ | 66.6K | 3.0% |
| GENDELL JEFFREY L | 59.2K | 2.7% |
| Boston Partners | 55.6K | 2.5% |
| LONDON CO OF VIRGINIA | 54.0K | 2.5% |
| STATE STREET CORP | 50.3K | 2.3% |
| GEODE CAPITAL MANAGEMENT, LLC | 49.4K | 2.2% |
| MORGAN STANLEY | 46.9K | 2.1% |
| REINHART PARTNERS, LLC. | 44.5K | 2.0% |
| T. Rowe Price Investment Management, Inc. | 34.2K | 1.6% |
| LORD, ABBETT & CO. LLC | 32.8K | 1.5% |
| AMERICAN CENTURY COMPANIES INC | 31.1K | 1.4% |
| NORGES BANK | 28.0K | 1.3% |
| Cannell & Spears LLC | 27.6K | 1.3% |
| BANK OF AMERICA CORP /DE/ | 25.0K | 1.1% |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC | 23.5K | 1.1% |
| Mraz, Amerine & Associates, Inc. | 22.2K | 1.0% |
Largest changes
| Manager | Action | Previous | Current | Change |
|---|---|---|---|---|
| AMERICAN CENTURY COMPANIES INC | Increased | 8.3K | 31.1K | +22.8K |
| GENDELL JEFFREY L | Increased | 37.8K | 59.2K | +21.4K |
| COOKE & BIELER LP | Reduced | 104.9K | 85.1K | -19.7K |
| FIDUCIARY MANAGEMENT INC /WI/ | Reduced | 85.1K | 66.6K | -18.5K |
| MORGAN STANLEY | Reduced | 59.3K | 46.9K | -12.4K |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Sold Out | 11.0K | 0 | -11.0K |
| Select Equity Group, L.P. | Sold Out | 10.6K | 0 | -10.6K |
| RAYMOND JAMES FINANCIAL INC | Reduced | 24.0K | 14.8K | -9.1K |
| Gotham Asset Management, LLC | Increased | 9.0K | 17.9K | +8.9K |
| Qube Research & Technologies Ltd | Increased | 1.0K | 9.7K | +8.7K |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC | Reduced | 7.8K | 61 | -7.8K |
| FIRST TRUST ADVISORS LP | Increased | 3.1K | 10.6K | +7.5K |
| GEODE CAPITAL MANAGEMENT, LLC | Increased | 42.1K | 49.4K | +7.3K |
| T. Rowe Price Investment Management, Inc. | Reduced | 41.5K | 34.2K | -7.3K |
| REINHART PARTNERS, LLC. | Increased | 37.4K | 44.5K | +7.1K |
| UBS Group AG | Increased | 10.4K | 16.2K | +5.8K |
| NEUBERGER BERMAN GROUP LLC | Reduced | 124.7K | 119.1K | -5.6K |
| BNP PARIBAS FINANCIAL MARKETS | Reduced | 6.6K | 1.2K | -5.5K |
| ARROWSTREET CAPITAL, LIMITED PARTNERSHIP | Increased | 1.9K | 7.3K | +5.4K |
| WINMILL & CO. INC | New | 0 | 4.8K | +4.8K |
| WCM INVESTMENT MANAGEMENT, LLC | Reduced | 6.0K | 1.2K | -4.8K |
| River Road Asset Management, LLC | Reduced | 120.5K | 115.9K | -4.6K |
| BlackRock, Inc. | Increased | 113.3K | 117.9K | +4.5K |
| CITADEL ADVISORS LLC | Increased | 2.6K | 7.1K | +4.5K |
| HRT FINANCIAL LP | Increased | 2.4K | 6.8K | +4.4K |
| MARSHALL WACE, LLP | Sold Out | 3.9K | 0 | -3.9K |
| GOLDMAN SACHS GROUP INC | Reduced | 15.8K | 12.2K | -3.6K |
| VANGUARD PORTFOLIO MANAGEMENT LLC | Reduced | 115.6K | 112.0K | -3.6K |
| Edgestream Partners, L.P. | Increased | 3.1K | 6.6K | +3.4K |
| JANE STREET GROUP, LLC | Increased | 13.8K | 17.2K | +3.4K |
| BANK OF AMERICA CORP /DE/ | Reduced | 28.4K | 25.0K | -3.3K |
| LONDON CO OF VIRGINIA | Reduced | 57.1K | 54.0K | -3.1K |
| SEI INVESTMENTS CO | Reduced | 11.1K | 8.1K | -3.0K |
| JPMORGAN CHASE & CO | Increased | 2.6K | 5.4K | +2.8K |
| Quantinno Capital Management LP | Increased | 9.8K | 12.6K | +2.8K |
| FULLER & THALER ASSET MANAGEMENT, INC. | Reduced | 104.6K | 101.9K | -2.7K |
| RENAISSANCE TECHNOLOGIES LLC | Sold Out | 2.6K | 0 | -2.6K |
| DIMENSIONAL FUND ADVISORS LP | Increased | 156.6K | 159.0K | +2.3K |
| D. E. Shaw & Co., Inc. | Reduced | 8.9K | 6.6K | -2.3K |
| AQR CAPITAL MANAGEMENT LLC | Reduced | 7.7K | 5.5K | -2.3K |
| DARK FOREST CAPITAL MANAGEMENT LP | Sold Out | 2.3K | 0 | -2.3K |
| Boston Partners | Reduced | 57.5K | 55.6K | -1.9K |
| Lighthouse Investment Partners, LLC | New | 0 | 1.9K | +1.9K |
| SOUTHEASTERN ASSET MANAGEMENT INC/TN/ | Reduced | 18.9K | 17.1K | -1.8K |
| ENVESTNET ASSET MANAGEMENT INC | Reduced | 15.6K | 13.8K | -1.7K |
| VANGUARD CAPITAL MANAGEMENT LLC | Reduced | 109.2K | 107.5K | -1.7K |
| XTX Topco Ltd | Increased | 250 | 1.6K | +1.4K |
| Wallace Capital Management Inc. | Increased | 78.8K | 80.1K | +1.3K |
| Russell Investments Group, Ltd. | Increased | 1.1K | 2.4K | +1.2K |
| Empowered Funds, LLC | Reduced | 1.3K | 103 | -1.2K |
| California Public Employees Retirement System | Reduced | 6.4K | 5.2K | -1.2K |
| DIVERSIFIED MANAGEMENT INC | Sold Out | 1.2K | 0 | -1.2K |
| Walleye Capital LLC | New | 0 | 1.1K | +1.1K |
| STATE STREET CORP | Increased | 49.2K | 50.3K | +1.1K |
| NORTHERN TRUST CORP | Reduced | 15.5K | 14.6K | -924 |
| Capula Management Ltd | Sold Out | 921 | 0 | -921 |
| CITIGROUP INC | Reduced | 1.4K | 483 | -917 |
| HORIZON KINETICS ASSET MANAGEMENT LLC | Reduced | 13.1K | 12.2K | -906 |
| Squarepoint Ops LLC | New | 0 | 905 | +905 |
| ExodusPoint Capital Management, LP | Increased | 611 | 1.4K | +832 |
13F filings are due 45 days after quarter end and cover long positions in U.S.-listed equities only, so this is a lagged and partial picture: shorts, bonds and foreign listings never appear. Options positions are excluded here rather than folded into the share counts. Political ownership is coming.