WTM - CIK 0000776867
WHITE MOUNTAINS INSURANCE GROUP LTD has filed 1,719 documents with the SEC between 1994 and 2026. The most frequent type is insider trade (634 filings), alongside the regular cadence of annual reports, quarterly reports, and event disclosures every public company must make. Use the filters to focus on one filing type, or flip the sort to trace the company's history from its earliest paperwork.
Data parsed from SEC EDGAR XBRL filings. See the full market cap rankings.
| Filing | Type | Filed | Period covered |
|---|---|---|---|
| Insider trade | 4 | 2026-05-22 | 2026-05-21 |
| Insider trade | 4 | 2026-05-22 | 2026-05-21 |
| Insider trade | 4 | 2026-05-22 | 2026-05-21 |
| Insider trade | 4 | 2026-05-22 | 2026-05-21 |
| Insider trade | 4 | 2026-05-22 | 2026-05-21 |
| Insider trade | 4 | 2026-05-22 | 2026-05-21 |
| New insider ownership | 3 | 2026-05-22 | 2026-05-21 |
| Insider trade | 4 | 2026-05-22 | 2026-05-21 |
| Insider trade | 4 | 2026-05-22 | 2026-05-21 |
| Insider trade | 4 | 2026-05-22 | 2026-05-21 |
| Major company event | 8-K | 2026-05-21 | 2026-05-21 |
| Major company event | 8-K | 2026-05-15 | 2026-05-14 |
| Institutional holdings | 13F-HR | 2026-05-12 | 2026-03-31 |
| SCHEDULE 13G/A | - | 2026-05-07 | - |
| Quarterly report | 10-Q | 2026-05-06 | 2026-03-31 |
| Major company event | 8-K | 2026-05-06 | 2026-05-06 |
| SCHEDULE 13G | - | 2026-04-30 | - |
| Major company event | 8-K | 2026-04-01 | 2026-04-01 |
| Annual report to shareholders | ARS | 2026-04-01 | 2025-12-31 |
| Proxy statement | DEF 14A | 2026-04-01 | 2026-05-21 |
| SCHEDULE 13G/A | - | 2026-03-27 | - |
| Insider trade | 4 | 2026-03-20 | 2026-03-19 |
| Insider trade | 4 | 2026-03-05 | 2026-03-04 |
| Annual report | 10-K | 2026-02-27 | 2025-12-31 |
| Insider trade | 4 | 2026-02-27 | 2026-02-25 |
| Insider trade | 4 | 2026-02-27 | 2026-02-25 |
| Insider trade | 4 | 2026-02-27 | 2026-02-25 |
| Insider trade | 4 | 2026-02-27 | 2026-02-25 |
| Insider trade | 4 | 2026-02-27 | 2026-02-25 |
| Major company event | 8-K | 2026-02-26 | 2026-02-26 |
| Institutional holdings | 13F-HR | 2026-02-12 | 2025-12-31 |
| SCHEDULE 13G/A | - | 2026-02-12 | - |
| Major company event | 8-K | 2026-02-06 | 2026-02-06 |
| SCHEDULE 13G | - | 2026-02-05 | - |
| Major company event | 8-K | 2026-01-07 | 2026-01-07 |
| Insider trade | 4 | 2026-01-05 | 2026-01-01 |
| Insider trade | 4 | 2026-01-02 | 2026-01-01 |
| New insider ownership | 3 | 2026-01-02 | 2026-01-01 |
| Insider trade | 4 | 2026-01-02 | 2026-01-01 |
| Insider trade | 4 | 2026-01-02 | 2026-01-01 |
| SC TO-I/A | - | 2025-12-29 | - |
| Insider trade | 4 | 2025-12-23 | 2025-12-23 |
| SC TO-I/A | - | 2025-12-22 | - |
| Insider trade (amended) | 4/A | 2025-12-22 | 2025-12-19 |
| Insider trade | 4 | 2025-12-22 | 2025-12-19 |
| Insider trade | 4 | 2025-12-22 | 2025-12-19 |
| Insider trade | 4 | 2025-12-16 | 2025-12-16 |
| Major company event | 8-K | 2025-12-08 | 2025-12-05 |
| Insider trade | 4 | 2025-11-26 | 2025-11-25 |
| SC TO-I | - | 2025-11-21 | - |