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.
Open-market trades, last 90 days
Open-market purchases (P) and sales (S) by White Mountains Insurance Group Ltd insiders, counted by Form 4 filing. Trades with a flagged price and duplicate filings are left out.
- Open-market buys
- 0 filings
- Open-market sells
- 0 filings
- Insiders trading
- 0
- Net value
- $0
- Purchases minus sales
Insider roster
Directors, officers and 10% owners who have filed a Form 4 for White Mountains Insurance Group Ltd, current and former, most recent filer first. Last reported holding is the position after the last non-derivative trade in their latest filing.
| Name | Title | Last reported holding | Last filing | Filings, past year |
|---|---|---|---|---|
| Tanner David Allen | Director | 2,012 | Aug 31, 2026 | 4 |
| Klar Stephen | Director | 113 | Aug 27, 2026 | 1 |
| Hicks Weston M | Director | 2,936 | May 22, 2026 | 1 |
| Choksi Mary C | Director | 1,993 | May 22, 2026 | 1 |
| Campbell Reid Tarlton | Director | 10,575 | May 22, 2026 | 3 |
| Carlson Peter M | Director | 852 | May 22, 2026 | 1 |
| Shank Suzanne F. | Director | 1,006 | May 22, 2026 | 1 |
| Gelston Philip A | Director | 1,703 | May 22, 2026 | 2 |
| Dillon Margaret | Director | 1,080 | May 22, 2026 | 1 |
| Chu John | Director | 335 | May 22, 2026 | 1 |
| Seelig Robert Lawrence | EVP & General Counsel | 17,857 | Mar 20, 2026 | 3 |
| Hildreth Michaela | MD & Chief Accounting Officer | 1,825 | Feb 27, 2026 | 3 |
| Caffrey Liam P | Chief Executive Officer | 3,650 | Feb 27, 2026 | 2 |
| Harrison Giles E | President | 2,675 | Feb 27, 2026 | 1 |
| Papamichael Michael A | Chief Financial Officer | 1,200 | Feb 27, 2026 | 2 |
| Rountree George Manning | Chief Executive Officer | 13,809 | Dec 22, 2025 | 1 |
| Yi Steven | Director | 525 | May 23, 2025 | 0 |
| Davis Morgan W | Director | 6,709 | Dec 29, 2022 | 0 |
Insider trades
Each row adds up one type of transaction in one Form 4 filing. Only open-market purchases (P) and sales (S) are shown by default; use the filters to see grants, option exercises and other codes.
| 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 |