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WTM · White Mountains Insurance Group Ltd · Holdings

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$2,056.85 -4.45 (-0.22%) At close · Sep 21
Market Cap
$4.92B
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.

Holders: 355
Total Value: $4,563,520,537
Total Shares: 2,200,995
Showing 1–100 of 355 holdings by value · page 1 of 4

Institutional Ownership Trend

26 quarters

Holder Concentration

Across 355 13F filers · Δ vs Mar 31, 2026
Top Holder
7.2%
Sep 2023 → Jun 2026 · range 7.1% – 11.2%
+0.1 pts
Top 5
28.3%
Sep 2023 → Jun 2026 · range 28.3% – 38.7%
−0.2 pts
Top 10
48.4%
Sep 2023 → Jun 2026 · range 48.4% – 58.2%
−2.0 pts
HHI
309
Sep 2023 → Jun 2026 · range 309 – 441
Broadly held−11

Quarterly Activity

vs Mar 31, 2026
New
41
Increased
95
Decreased
144
Sold Out
52
Unchanged
75
Holder count: -11
Institutional value: -6.0%
Shares held: -0.4%

Top Buyers

vs Mar 31, 2026
Institution Added Now Holds Open

Top Sellers

vs Mar 31, 2026
Institution Sold Now Holds Open

Top New Positions

vs Mar 31, 2026
Institution Acquired Value (USD) Open

Top Sold-Out Positions

vs Mar 31, 2026
Institution Previously Held Last Value (USD) Open
Showing 100 of 355
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Holder Value (USD) % of 13F Shares Open
Key facts CIK 776867 CUSIP G9618E107 13F (30d) 6 filings 6 filers Visit website Investor relations