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.
Q4 2025 vs. Q3 2025
How the institutions holding White Mountains Insurance Group Ltd changed between Q3 2025 and Q4 2025.
All holders in Q4 2025All holders in Q3 2025
| Measure | Q3 2025 | Of which not filed for Q4 2025 | Q4 2025 | Change |
|---|---|---|---|---|
| Holders | 338 | 5 | 353 | +20 |
| Shares | 2.33M | 1.81K | 2.25M | −77.3K (−3.3%) |
| Value | $3.89B | $3.10M | $4.67B | +$782.8M (+20.1%) |
5 institutions that held it in Q3 2025 haven't filed for Q4 2025 yet. Not filing isn't selling, so the changes leave them out.
New holders (55)
Institutions that held White Mountains Insurance Group Ltd at the end of Q4 2025 but not at the end of Q3 2025.
Sold out (35)
Institutions that held White Mountains Insurance Group Ltd at the end of Q3 2025 and filed for Q4 2025 without it.
Not filed for Q4 2025 yet (5)
Institutions that held White Mountains Insurance Group Ltd at the end of Q3 2025 and haven't filed a 13F for Q4 2025. Not filing isn't selling, so they aren't counted as sold out.
| Institution | Shares, Q3 2025 | Value, Q3 2025 |
|---|---|---|
| Cove Street Capital, LLC | 1,083 | $1.81M |
| Kathleen S. Wright Associates Inc. | 340 | $646.8K |
| Glenmede Investment Management, LP | 362 | $605.1K |
| Hemington Wealth Management | 14 | $23.0K |
| Binnacle Investments Inc | 7 | $11.7K |