WTM · Insider Trading
White Mountains Insurance Group Ltd.
Every open-market purchase and sale reported by WTM officers, directors and 10%+ beneficial owners on SEC Form 4, which must be filed within two business days of the transaction. Sales often reflect scheduled 10b5-1 plans or tax withholding rather than a directional view, so read counts alongside the size and the filer.
| Filed | Insider | Role | Type | Shares | Value |
|---|---|---|---|---|---|
| 2026-08-31 | David Allen Tanner | Director | G | −2 | — |
| 2026-08-27 | Stephen Klar | Director | A | +113 | — |
| 2026-05-22 | Reid Tarlton Campbell | Director | A | +135 | — |
| 2026-05-22 | Peter M Carlson | Director | A | +135 | — |
| 2026-05-22 | Mary C Choksi | Director | A | +135 | — |
| 2026-05-22 | John Chu | Director | A | +135 | — |
| 2026-05-22 | Margaret Dillon | Director | A | +135 | — |
| 2026-05-22 | Philip A Gelston | Director | A | +135 | — |
| 2026-05-22 | Weston M Hicks | Director | A | +190 | — |
| 2026-05-22 | Suzanne F. Shank | Director | A | +135 | — |
| 2026-05-22 | David Allen Tanner | Director | A | +135 | — |
| 2026-03-20 | Robert Lawrence Seelig | EVP & General Counsel | G | −50 | — |
| 2026-03-05 | David Allen Tanner | Director | G | −225 | — |
| 2026-02-27 | Robert Lawrence Seelig | EVP & General Counsel | A | +775 | — |
| 2026-02-27 | Michael A Papamichael | Chief Financial Officer | A | +500 | — |
| 2026-02-27 | Michaela Hildreth | MD & Chief Accounting Officer | A | +600 | — |
| 2026-02-27 | Giles E Harrison | President | A | +775 | — |
| 2026-02-27 | Liam P Caffrey | Chief Executive Officer | A | +1,500 | — |
| 2026-01-05 | Michaela Hildreth | MD & Chief Accounting Officer | F | −274 | −$569.38K |
| 2026-01-02 | Liam P Caffrey | Chief Executive Officer | F | −425 | −$883.16K |
| 2026-01-02 | Robert Lawrence Seelig | EVP & General Counsel | F | −398 | −$827.06K |
| 2026-01-02 | Michael A Papamichael | Chief Financial Officer | F | −131 | −$272.22K |
| 2025-12-23 | Michaela Hildreth | MD & Chief Accounting Officer | G | −60 | — |
| 2025-12-22 | Reid Tarlton Campbell | Director | Sell | −5,000 | −$10.25M |
| 2025-12-22 | George Manning Rountree | Chief Executive Officer | Sell | −5,000 | −$10.25M |
| 2025-12-22 | Reid Tarlton Campbell | Director | Sell | −5,000 | — |
| 2025-12-16 | Philip A Gelston | Director | Sell | −165 | −$338.00K |
| 2025-11-26 | Reid Tarlton Campbell | Director | G | −50 | — |
| 2025-11-10 | David Allen Tanner | Director | G | −4 | — |
| 2025-05-27 | Suzanne F. Shank | Director | A | +150 | — |
| 2025-05-23 | Reid Tarlton Campbell | Director | A | +150 | — |
| 2025-05-23 | Peter M Carlson | Director | A | +150 | — |
| 2025-05-23 | Mary C Choksi | Director | A | +150 | — |
| 2025-05-23 | Margaret Dillon | Director | A | +150 | — |
| 2025-05-23 | Philip A Gelston | Director | A | +150 | — |
| 2025-05-23 | Weston M Hicks | Director | A | +210 | — |
| 2025-05-23 | David Allen Tanner | Director | A | +150 | — |
| 2025-05-23 | Steven Yi | Director | A | +150 | — |
| 2025-02-28 | Michaela Hildreth | MD & Chief Accounting Officer | A | +625 | — |
| 2025-02-28 | Robert Lawrence Seelig | EVP & General Counsel | A | +825 | — |
| 2025-02-28 | Giles E Harrison | EVP & Chief Strategy Officer | A | +900 | — |
| 2025-02-28 | Liam P Caffrey | EVP& Chief Financial Officer | A | +1,025 | — |
| 2025-02-28 | George Manning Rountree | Chief Executive Officer | A | +1,625 | — |
| 2025-01-03 | Michaela Hildreth | MD & Chief Accounting Officer | F | −323 | −$628.25K |
| 2025-01-03 | Robert Lawrence Seelig | EVP & General Counsel | F | −496 | −$964.75K |
| 2025-01-03 | Liam P Caffrey | President & CFO | F | −420 | −$816.93K |
| 2025-01-03 | George Manning Rountree | Chief Executive Officer | F | −1,067 | −$2.08M |
| 2024-12-02 | Michaela Hildreth | MD & Chief Accounting Officer | G | −75 | — |
| 2024-06-10 | Giles E Harrison | EVP & Chief Strategy Officer | A | +1,000 | — |
| 2024-05-24 | Weston M Hicks | Director | A | +230 | — |
| Insider | Role | Shares Held | Value |
|---|---|---|---|
| Robert Lawrence Seelig | EVP & General Counsel | 17,861 | $38.71M |
| George Manning Rountree | Chief Executive Officer | 13,931 | $30.19M |
| Reid Tarlton Campbell | Director | 10,694 | $23.18M |
| Liam P Caffrey | Chief Executive Officer | 3,658 | $7.93M |
| Weston M Hicks | Director | 2,936 | $6.36M |
| Giles E Harrison | President | 2,677 | $5.80M |
| David Allen Tanner | Director | 2,012 | $4.36M |
| Mary C Choksi | Director | 1,993 | $4.32M |
| Michaela Hildreth | MD & Chief Accounting Officer | 1,845 | $4.00M |
| Philip A Gelston | Director | 1,703 | $3.69M |
| Michael A Papamichael | Chief Financial Officer | 1,212 | $2.63M |
| Margaret Dillon | Director | 1,080 | $2.34M |
| Suzanne F. Shank | Director | 1,006 | $2.18M |
| Peter M Carlson | Director | 852 | $1.85M |
| Steven Yi | Director | 525 | $1.14M |
| John Chu | Director | 335 | $725.99K |
| Stephen Klar | Director | 113 | $244.88K |
Form 4 reports a change in beneficial ownership by an officer, director or 10%+ holder, and must be filed within two business days of the transaction — so this is close to real time, unlike the 45-day-lagged 13F institutional data.
Transaction codes matter more than the raw buy/sell count. Code P is an open-market purchase — an insider choosing to buy with their own money, which is the signal most research treats as informative. Code S is a sale, but sales are frequently pre-scheduled under a 10b5-1 plan or cover tax withholding on vesting equity, so a run of sales often says nothing directional. Codes A and M are grants and option exercises rather than open-market decisions.
Full filing history and per-insider positions are on the WTM quote page; the site-wide leaderboard is on the insider transactions hub.
Market data may be delayed, incomplete, or inaccurate. Not a recommendation to buy, sell, or hold any security. Verify quotes with your broker before trading. See Terms §17.