White Mountains Insurance Group Ltd
WTM- Exchange
- NYSE
- Industry
- Fire, Marine & Casualty Insurance
- SEC CIK
- 0000776867
No open-market purchases or sales by White Mountains Insurance Group Ltd insiders were filed in the last 90 days; 356 institutions reported holding it in 13F filings for Q2 2026, worth $4.57B in total; Southeastern Asset Management (Longleaf) is the only superinvestor holding it.
Key figures
- Insider buysOpen market, last 90 days
- 0
- Insider sellsOpen market, last 90 days
- 0
- 13F holdersQ2 2026, −7 vs. previous quarter
- 356
- 13F valueReported value at the end of Q2 2026
- $4.57B
- Superinvestors holdingAt the end of Q2 2026
- 1
Price chart
Superinvestors holding WTM, Q2 2026
1 superinvestor reports holding White Mountains Insurance Group Ltd on Form 13F. Percentages are the stock's share of each portfolio.
Southeastern Asset Management (Longleaf)
Mason Hawkins
1.8%
White Mountains Insurance Group Ltd's share of the portfolio
- Shares
- 17,104
- Value
- $35.5M
Latest insider trades
Open-market purchases and sales by White Mountains Insurance Group Ltd insiders from Form 4, newest first.
| Filed (ET) | Trade date | Filing delay | Insider | Transaction | Shares | Avg price | Value | Holding change | Flags |
|---|---|---|---|---|---|---|---|---|---|
| Dec 22, 2025 (view filing) | Dec 19 | 3 days | Campbell Reid TarltonDirector | SSale | −5.00K | $2,050.00 | −$10.3M | −32.4%10.4K after | Amended |
| Dec 22, 2025 (view filing) | Dec 19 | 3 days | Rountree George ManningChief Executive Officer | SSale | −5.00K | $2,050.00 | −$10.3M | −26.6%13.8K after | |
| Dec 16, 2025 (view filing) | Dec 16 | Same day | Gelston Philip ADirector | SSale | −165 | $2,048.51 | −$338.0K | −9.5%1.57K after | |
| Nov 20, 2023 (view filing) | Nov 17 | 3 days | Hicks Weston MDirector | PPurchase | +1.00K | $1,480.56 | +$1.48M | +76.6%2.31K after | Amended5 lots |
| Dec 27, 2022 (view filing) | Dec 22 | 5 days | Hildreth MichaelaMD & Chief Accounting Officer | SSale | −100 | $1,371.84 | −$137.2K | −6.4%1.46K after | |
| Sep 22, 2022 (view filing) | Sep 20 | 2 days | Carlson Peter MDirector | SSale | −200 | $1,400.00 | −$280.0K | −20.2%788 after | |
| Sep 22, 2022 (view filing) | Sep 20 | 2 days | Davis Morgan WDirector | SSale | −945 | $1,400.00 | −$1.32M | −12.0%6.91K after | |
| Jun 1, 2022 (view filing) | May 31 | 1 day | Hildreth MichaelaMD & Chief Accounting Officer | SSale | −100 | $1,270.94 | −$127.1K | −6.0%1.56K after |
Top 10 13F holders, Q2 2026
The largest institutional positions in White Mountains Insurance Group Ltd at the end of Q2 2026; share changes are against Q1 2026.
| Institution | Shares | Value | % of portfolio | Change in shares | Action |
|---|---|---|---|---|---|
| Dimensional Fund Advisors LP | 158,954 | $329.6M | 0.06% | +2,336+1.5% | Added |
| Neuberger Berman Group LLC | 119,141 | $247.0M | 0.16% | −5,574−4.5% | Reduced |
| BlackRock, Inc. | 117,871 | $244.4M | 0.00% | +4,543+4.0% | Added |
| River Road Asset Management, LLC | 115,880 | $240.3M | 2.67% | −4,639−3.8% | Reduced |
| Vanguard Portfolio Management LLC | 111,969 | $232.2M | 0.01% | −3,584−3.1% | Reduced |
| Vanguard Capital Management LLC | 107,479 | $222.8M | 0.00% | −1,678−1.5% | Reduced |
| Fuller & Thaler Asset Management, Inc. | 101,892 | $211.3M | 0.58% | −2,669−2.6% | Reduced |
| Cooke & Bieler LP | 85,120 | $176.5M | 2.04% | −19,737−18.8% | Reduced |
| Wallace Capital Management Inc. | 80,067 | $166.0M | 18.20% | +1,272+1.6% | Added |
| Fiduciary Management Inc | 66,550 | $138.0M | 1.96% | −18,516−21.8% | Reduced |