Over the past 12 months, White Mountains Insurance insiders made no open-market purchases, and sold at least $10.59 million of stock on the open market (10.16K shares).
| # | Insider | Position | Direct | Indirect | Total | Share of Insiders | Last Filed |
|---|---|---|---|---|---|---|---|
| 1 | Robert Lawrence Seelig | Evp General Counsel | 20,357 | 0 | 20,357 | 23.4% | 20 Mar, 2026 |
| 2 | George Manning Rountree | Chief Executive Officer | 19,234 | 0 | 19,234 | 22.1% | 22 Dec, 2025 |
| 3 | Reid Tarlton Campbell | President | 10,575 | 0 | 10,575 | 12.1% | 21 May, 2026 |
| 4 | Liam P Caffrey | Chief Executive Officer | 8,705 | 0 | 8,705 | 10.0% | 25 Feb, 2026 |
| 5 | Morgan W Davis | President, American Centennial | 6,709 | 0 | 6,709 | 7.7% | 29 Dec, 2022 |
| 6 | Michaela Hildreth | Md Chief Accounting Officer | 4,316 | 0 | 4,316 | 5.0% | 25 Feb, 2026 |
| 7 | Weston M Hicks | Director | 2,936 | 0 | 2,936 | 3.4% | 21 May, 2026 |
| 8 | Giles E Harrison | President | 2,675 | 0 | 2,675 | 3.1% | 25 Feb, 2026 |
| 9 | David Allen Tanner | Director | 2,012 | 0 | 2,012 | 2.3% | 31 Aug, 2026 |
| 10 | Mary C Choksi | Director | 1,993 | 0 | 1,993 | 2.3% | 21 May, 2026 |
| 11 | Michael A Papamichael | Chief Financial Officer | 1,972 | 0 | 1,972 | 2.3% | 25 Feb, 2026 |
| 12 | Philip A Gelston | Director | 1,703 | 0 | 1,703 | 2.0% | 21 May, 2026 |
| 13 | Margaret Dillon | Director | 1,080 | 0 | 1,080 | 1.2% | 21 May, 2026 |
| 14 | Suzanne F. Shank | Director | 1,006 | 0 | 1,006 | 1.2% | 21 May, 2026 |
| 15 | Peter M Carlson | Director | 852 | 0 | 852 | 1.0% | 21 May, 2026 |
| 16 | Steven Yi | Director | 525 | 0 | 525 | 0.6% | 23 May, 2025 |
| 17 | John Chu | Director | 335 | 0 | 335 | 0.4% | 21 May, 2026 |
| 18 | Stephen Klar | Director | 113 | 0 | 113 | 0.1% | 27 Aug, 2026 |
Each row is that insider’s most recently reported position, from Form 4 filings over the last 60 months — which is why this total does not tie to the quarterly series above, where a quarter counts only the insiders who filed in it. Shares held through a fund or institutional portfolio are counted on the institutional ownership page instead.
| Date | Insider | Position | Transaction | Shares | Price | Value | Shares Held After | Ownership |
|---|---|---|---|---|---|---|---|---|
| 31 Aug, 2026 | David Allen Tanner | Director | Disposed G | 2 | $0.00 | $0 | 2,012 | Direct |
| 26 Aug, 2026 | Stephen Klar | Director | Acquired A | 113 | $0.00 | $0 | 113 | Direct |
| 21 May, 2026 | David Allen Tanner | Director | Acquired A | 135 | $0.00 | $0 | 2,014 | Direct |
| 21 May, 2026 | Reid Tarlton Campbell | Director | Acquired A | 135 | $0.00 | $0 | 10,575 | Direct |
| 21 May, 2026 | Weston M Hicks | Director | Acquired A | 190 | $0.00 | $0 | 2,936 | Direct |
| 21 May, 2026 | Margaret Dillon | Director | Acquired A | 135 | $0.00 | $0 | 1,080 | Direct |
| 21 May, 2026 | Suzanne F. Shank | Director | Acquired A | 135 | $0.00 | $0 | 1,006 | Direct |
| 21 May, 2026 | Philip A Gelston | Director | Acquired A | 135 | $0.00 | $0 | 1,703 | Direct |
| 21 May, 2026 | Mary C Choksi | Director | Acquired A | 135 | $0.00 | $0 | 1,993 | Direct |
| 21 May, 2026 | John Chu | Director | Acquired A | 135 | $0.00 | $0 | 335 | Direct |
| 21 May, 2026 | Peter M Carlson | Director | Acquired A | 135 | $0.00 | $0 | 852 | Direct |
| 19 Mar, 2026 | Robert Lawrence Seelig | Evp General Counsel | Disposed G | 50 | $0.00 | $0 | 17,857 | Direct |
| 04 Mar, 2026 | David Allen Tanner | Director | Disposed G | 225 | $0.00 | $0 | 1,879 | Direct |
| 25 Feb, 2026 | Michaela Hildreth | Md Chief Accounting Officer | Acquired A | 600 | $0.00 | $0 | 1,825 | Direct |
| 25 Feb, 2026 | Robert Lawrence Seelig | Evp General Counsel | Acquired A | 775 | $0.00 | $0 | 2,500 | Direct |
| 25 Feb, 2026 | Michael A Papamichael | Chief Financial Officer | Acquired A | 500 | $0.00 | $0 | 1,200 | Direct |
| 25 Feb, 2026 | Giles E Harrison | President | Acquired A | 775 | $0.00 | $0 | 2,675 | Direct |
| 25 Feb, 2026 | Liam P Caffrey | Chief Executive Officer | Acquired A | 1,500 | $0.00 | $0 | 3,650 | Direct |
| 01 Jan, 2026 | Michaela Hildreth | Md Chief Accounting Officer | Disposed F | 274 | $2,078.03 | $569.38K | 2,491 | Direct |
| 01 Jan, 2026 | Robert Lawrence Seelig | Evp General Counsel | Disposed F | 398 | $2,078.03 | $827.06K | 17,907 | Direct |