17 insiders reported 38 Form 4 transactions for WHITE MOUNTAINS INSURANCE GROUP LTD (WTM) over the past 18 months (most recent 2026-08-31). Recent activity: Tanner David Allen (Director) Sell 2 shares, Klar Stephen (Director) Buy 113 shares, Chu John (Director) Buy 135 shares, SHANK SUZANNE F. (Director) Buy 135 shares, CAMPBELL REID TARLTON (Director) Buy 135 shares. Source: SEC Form 4.
| Date | Insider | Title | Type | Shares | Value |
|---|---|---|---|---|---|
| 2026-08-31 | Tanner David Allen | Director | Sell | 2 | $0 |
| 2026-08-27 | Klar Stephen | Director | Buy | 113 | $0 |
| 2026-05-22 | Chu John | Director | Buy | 135 | $0 |
| 2026-05-22 | SHANK SUZANNE F. | Director | Buy | 135 | $0 |
| 2026-05-22 | CAMPBELL REID TARLTON | Director | Buy | 135 | $0 |
| 2026-05-22 | Gelston Philip A | Director | Buy | 135 | $0 |
| 2026-05-22 | Hicks Weston M | Director | Buy | 190 | $0 |
| 2026-05-22 | CHOKSI MARY C | Director | Buy | 135 | $0 |
| 2026-05-22 | Dillon Margaret | Director | Buy | 135 | $0 |
| 2026-05-22 | Carlson Peter M | Director | Buy | 135 | $0 |
| 2026-05-22 | Tanner David Allen | Director | Buy | 135 | $0 |
| 2026-03-20 | SEELIG ROBERT LAWRENCE | EVP & General Counsel | Sell | 50 | $0 |
| 2026-03-05 | Tanner David Allen | Director | Sell | 225 | $0 |
| 2026-02-27 | Hildreth Michaela | MD & Chief Accounting Officer | Buy | 600 | $0 |
| 2026-02-27 | SEELIG ROBERT LAWRENCE | EVP & General Counsel | Buy | 775 | $0 |
| 2026-02-27 | Harrison Giles E | President | Buy | 775 | $0 |
| 2026-02-27 | Papamichael Michael A | Chief Financial Officer | Buy | 500 | $0 |
| 2026-02-27 | Caffrey Liam P | Chief Executive Officer | Buy | 1,500 | $0 |
| 2026-01-05 | Hildreth Michaela | MD & Chief Accounting Officer | Sell | 274 | $569,380 |
| 2026-01-02 | Papamichael Michael A | Chief Financial Officer | Sell | 131 | $272,222 |
| 2026-01-02 | Caffrey Liam P | Chief Executive Officer | Sell | 425 | $883,163 |
| 2026-01-02 | SEELIG ROBERT LAWRENCE | EVP & General Counsel | Sell | 398 | $827,056 |
| 2025-12-23 | Hildreth Michaela | MD & Chief Accounting Officer | Sell | 60 | $0 |
| 2025-12-22 | Rountree George Manning | Chief Executive Officer | Sell | 5,000 | $10.2M |
| 2025-12-22 | CAMPBELL REID TARLTON | Director | Sell | 5,000 | $0 |
Source: SEC Form 4 filings · as of 2026-08-31