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WTM · White Mountains Insurance Group Ltd

$2,136.78 +24.87 (+1.18%) At close · Aug 6
Market Cap
$5.23B
Shares
2.39M

Institutional ownership from SEC Form 13F filings. Investment managers with more than $100 million in U.S. equities must disclose their positions every quarter, within 45 days of quarter-end, so the holdings shown can lag the market by up to a quarter.

The Jun 30, 2026 filing window is still open — showing the latest known positions. Funds that have not filed yet carry their prior-quarter positions; a fund that filed without this stock counts as sold out. Pick a completed quarter in the Quarter selector below to see a single quarter with position changes.
Holders: 358
Total Value: $4,000,753,303
Total Shares: 1,942,297
Showing 1–100 of 358 holdings by value · page 1 of 4

Institutional Ownership Trend

26 quarters

Holder Concentration

Across 359 13F filers
Top Holder
8.4%
Jun 2023 → Mar 2026 · range 8.4% – 12.1%
of institutional value
Top 5
33.4%
Jun 2023 → Mar 2026 · range 33.4% – 41.6%
of institutional value
Top 10
54.2%
Jun 2023 → Mar 2026 · range 54.2% – 63.0%
of institutional value
HHI
371
Jun 2023 → Mar 2026 · range 371 – 505
Broadly held
Showing 100 of 358
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Holder Value (USD) % of 13F Shares Open
Key facts CIK 776867 CUSIP G9618E107 13F (30d) 129 filings 129 filers Visit website Investor relations