White Mountains Insurance GPWTM
13F holders, Q1 2026 (March 31)368holders +15
43new positions
26sold out
7famous investors
$2197.48avg. 13F price*
At the end of Q1 2026, 368 institutions reported holding White Mountains Insurance GP (WTM) in their 13F filings, up 15 from Q4 2025. 43 opened new positions and 26 sold out. The largest holders were Dimensional Fund Advisors LP ($344.1M), Neuberger Berman Group LLC ($274.0M) and River Road Asset Management, LLC ($264.8M). 7 famous investors held it, including Joel Greenblatt (0.1% of Gotham Asset Management's portfolio), David E. Shaw (0.0% of D. E. Shaw & Co.'s portfolio) and Jim Simons / Peter Brown (0.0% of Renaissance Technologies's portfolio).
- Company
- White Mountains Insurance GP
- CUSIP
- G9618E107
- Latest filing quarter
- Q2 2026
History
Number of 13F holders
Total Exit/New Position Q4 2025 → Q1 2026
| Institutions | Total Value | |
|---|---|---|
| New Positions | 43 | $52.5M |
| Exits | 26 | $16.5M |
All 13F filers, Q4 2025 → Q1 2026: 125,233 shares bought and 136,306 shares sold, net −11,073 shares. Counts holders who added, trimmed, opened or closed a position; split-adjusted.
Ownership 368 holders
| Dimensional Fund Advisors LP | 0.07% | Add +0.0% | 156,618 | $344.1M |
| Neuberger Berman Group LLC | 0.21% | Reduce -3.8% | 124,715 | $274.0M |
| River Road Asset Management, LLC | 3.01% | Reduce -0.3% | 120,519 | $264.8M |
| Vanguard Portfolio Management LLC | 0.01% | — | 115,553 | $253.9M |
| BlackRock, Inc. | 0.00% | Add +0.9% | 113,328 | $249.0M |
| Vanguard Capital Management LLC | 0.01% | — | 109,157 | $239.8M |
| Cooke & Bieler LP | 2.61% | Reduce -1.6% | 104,857 | $230.4M |
| Fuller & Thaler Asset Management, Inc. | 0.77% | Reduce -3.3% | 104,561 | $229.7M |
| Fiduciary Management Inc. | 2.32% | Reduce -5.8% | 85,066 | $186.9M |
| Wallace Capital Management Inc. | 19.88% | Reduce -1.9% | 78,795 | $173.1M |
| Morgan Stanley | 0.01% | Reduce -27.8% | 59,295 | $130.3M |
| Boston Partners | 0.13% | Reduce -25.3% | 57,459 | $126.2M |
| London Co. of Virginia | 0.77% | Reduce -2.7% | 57,131 | $125.5M |
| State Street Corp. | 0.00% | Reduce -3.0% | 49,158 | $108.0M |
| Geode Capital Management, LLC | 0.01% | Add +1.4% | 42,119 | $92.6M |
| T. Rowe Price Investment Management, Inc. | 0.06% | Reduce -6.8% | 41,513 | $91.2M |
| Gendell Jeffrey L | 1.13% | Add +16.3% | 37,814 | $83.1M |
| Reinhart Partners, Llc. | 2.36% | Reduce -15.0% | 37,374 | $82.1M |
| Lord, Abbett & Co. LLC | 0.25% | Reduce -2.0% | 33,110 | $72.7M |
| Bank of America Corp. | 0.00% | Reduce -1.6% | 28,358 | $62.3M |
| Cannell & Spears LLC | 1.22% | Reduce -0.3% | 28,027 | $61.6M |
| Charles Schwab Investment Management Inc. | 0.01% | Add +4.3% | 24,241 | $53.3M |
| Raymond James Financial Inc. | 0.02% | Reduce -0.1% | 23,951 | $52.6M |
| Mraz, Amerine & Associates, Inc. | 7.19% | Reduce -2.0% | 22,179 | $48.7M |
| Southeastern Asset Management Inc. | 2.04% | Reduce -40.4% | 18,864 | $41.4M |
| Allspring Global Investments Holdings, LLC | 0.07% | Reduce -7.8% | 18,612 | $40.5M |
| Brown Advisory Inc. | 0.06% | Reduce -5.9% | 17,844 | $39.2M |
| Goldman Sachs Group Inc. | 0.00% | Add +200.1% | 15,783 | $34.7M |
| Envestnet Asset Management Inc. | 0.01% | Reduce -1.5% | 15,563 | $34.2M |
| Northern Trust Corp. | 0.00% | Reduce -7.0% | 15,495 | $34.0M |
| Vanguard Fiduciary Trust Co. | 0.01% | — | 15,186 | $33.4M |
| Wellington Management Group LLP | 0.01% | Reduce -6.5% | 14,884 | $32.7M |
| Boussard & Gavaudan Investment Management LLP | 7.37% | New | 13,975 | $31.0M |
| Jane Street Group, LLC | 0.03% | Add +708.9% | 13,808 | $30.3M |
| Horizon Kinetics Asset Management LLC | 0.31% | Reduce -0.1% | 13,112 | $28.8M |
| Elkhorn Partners Limited Partnership | 17.76% | Reduce -6.6% | 12,700 | $27.9M |
| Victory Capital Management Inc. | 0.02% | Add +77.0% | 11,145 | $24.5M |
| Sei Investments Co. | 0.02% | Add +40.2% | 11,098 | $24.4M |
| Susquehanna International Group, LLP | 0.03% | Add +8206.8% | 10,965 | $24.1M |
| Select Equity Group, L.P. | 0.12% | Reduce -46.4% | 10,560 | $23.2M |
| UBS Group AG | 0.00% | Add +74.0% | 10,441 | $22.9M |
| Quantinno Capital Management LP | 0.04% | Add +34.6% | 9,784 | $21.5M |
| Speece Thorson Capital Group Inc. | 4.70% | Reduce -11.9% | 9,397 | $20.6M |
| Gotham Asset Management | 0.06% | Add +34.7% | 9,047 | $19.9M |
| D. E. Shaw & Co. | 0.02% | Add +3.7% | 8,910 | $19.6M |
| Wells Fargo & Company | 0.00% | Reduce -3.9% | 8,782 | $19.3M |
| Bank of New York Mellon Corp | 0.00% | Reduce -4.4% | 8,444 | $18.6M |
| American Century Companies Inc. | 0.01% | Add +828.3% | 8,308 | $18.3M |
| GW&K Investment Management, LLC | 0.15% | Reduce -8.1% | 7,926 | $17.4M |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC | 0.00% | Add +2.2% | 7,826 | $17.2M |
| AQR Capital Management | 0.01% | Add +72.9% | 7,738 | $17.0M |
| Thompson Siegel & Walmsley LLC | 0.28% | Reduce -19.2% | 7,209 | $15.8M |
| BNP Paribas Financial Markets | 0.01% | Add +98.3% | 6,623 | $14.6M |
| Royce & Associates LP | 0.14% | Add +8.6% | 6,460 | $14.2M |
| California Public Employees Retirement System | 0.01% | Reduce -4.5% | 6,414 | $14.1M |
| Hotchkis & Wiley Capital Management LLC | 0.04% | Reduce -10.4% | 6,048 | $13.3M |
| WCM Investment Management, LLC | 0.03% | Reduce -43.9% | 5,995 | $13.2M |
| Williams Jones Wealth Management, LLC. | 0.14% | Add +0.0% | 5,194 | $11.4M |
| Swiss National Bank | 0.01% | Reduce -1.0% | 5,036 | $11.1M |
| Franklin Resources Inc. | 0.00% | Add +1099.5% | 4,798 | $10.5M |
| Nuveen, LLC | 0.00% | Add +24.0% | 4,309 | $9.5M |
| Phocas Financial Corp. | 1.48% | Reduce -21.8% | 4,292 | $9.4M |
| Rhumbline Advisers | 0.01% | Reduce -0.8% | 4,132 | $9.1M |
| Creative Planning | 0.01% | Add +18.6% | 4,049 | $8.9M |
| Marshall Wace, LLP | 0.01% | Add +253.2% | 3,878 | $8.5M |
| Lee Danner & Bass Inc. | 0.44% | Add +3.2% | 3,203 | $7.0M |
| Edgestream Partners, L.P. | 0.23% | Add +491.7% | 3,130 | $6.9M |
| First Trust Advisors LP | 0.00% | Reduce -32.9% | 3,058 | $6.7M |
| Invesco Ltd. | 0.00% | Reduce -0.9% | 2,967 | $6.5M |
| California State Teachers Retirement System | 0.01% | Add +17.5% | 2,887 | $6.3M |
| Ameriprise Financial Inc. | 0.00% | Reduce -6.1% | 2,866 | $6.3M |
| Renaissance Technologies | 0.01% | Add +74.0% | 2,611 | $5.7M |
| Citadel Advisors | 0.00% | Add +118.2% | 2,603 | $5.7M |
| JPMorgan Chase & Co. | 0.00% | Add +42.1% | 2,567 | $5.6M |
| New York State Common Retirement Fund | 0.01% | No change | 2,513 | $5.5M |
| Triad Investment Management | 6.52% | Reduce -1.4% | 2,513 | $5.5M |
| MML Investors Services, LLC | 0.01% | Reduce -16.2% | 2,459 | $5.4M |
| Legal & General Group Plc | 0.00% | Reduce -20.7% | 2,408 | $5.3M |
| HRT Financial LP | 0.01% | Add +1685.7% | 2,375 | $5.2M |
| VANGUARD ASSET MANAGEMENT, Ltd | 0.00% | — | 2,325 | $5.1M |
| State Board of Administration of Florida Retirement System | 0.01% | Reduce -19.0% | 2,261 | $5.0M |
| Dark Forest Capital Management LP | 0.44% | Reduce -37.6% | 2,255 | $5.0M |
| T. Rowe Price Associates Inc. | 0.00% | Add +11.1% | 2,211 | $4.9M |
| Robeco Institutional Asset Management B.V. | 0.01% | Add +249.8% | 2,179 | $4.8M |
| DAVENPORT & Co LLC | 0.03% | No change | 2,123 | $4.7M |
| Bradley Foster & Sargent Inc. | 0.07% | Reduce -63.3% | 2,002 | $4.4M |
| Arrowstreet Capital, Limited Partnership | 0.00% | Add +135.9% | 1,913 | $4.2M |
| Parsons Capital Management Inc. | 0.19% | Add +0.8% | 1,888 | $4.1M |
| Cerity Partners LLC | 0.01% | Reduce -47.3% | 1,867 | $4.1M |
| Atlantic Union Bankshares Corp | 0.07% | No change | 1,765 | $3.9M |
| Focus Partners Wealth | 0.00% | Reduce -29.9% | 1,129 | $3.8M |
| Agf Management Ltd. | 0.02% | Add +20.9% | 1,703 | $3.7M |
| Regency Capital Management Inc.\DE | 1.51% | Reduce -6.1% | 1,535 | $3.4M |
| Oppenheimer Asset Management Inc. | 0.04% | Reduce -1.5% | 1,480 | $3.3M |
| HighTower Advisors, LLC | 0.00% | No change | 1,447 | $3.2M |
| Citigroup Inc. | 0.00% | Reduce -24.3% | 1,400 | $3.1M |
| LPL Financial LLC | 0.00% | Reduce -29.0% | 1,395 | $3.1M |
| Corient Private Wealth LP | 0.00% | Add +54.3% | 1,398 | $3.0M |
| Tidal Investments LLC | 0.01% | Add +560.8% | 1,348 | $3.0M |
| Stifel Financial Corp. | 0.00% | Reduce -1.4% | 1,294 | $2.8M |
"% of holder's portfolio" is WTM's weight in each manager's 13F, not the share of White Mountains Insurance GP the manager owns.