Ranked by reported Q2 2026 13F market value
Share of total reported institutional value in WTM held by the largest 10 / 25 filers.
| # | Institution | Shares Held | Market Value | QoQ Change | Ownership % | % of Fund |
|---|---|---|---|---|---|---|
| 1 | DIMENSIONAL FUND ADVISORS LP | 159K | $329.6M | +1.5% | 6.418% | 0.06% |
| 2 | Neuberger Berman Group LLC | 119K | $247.0M | -4.5% | 4.811% | 0.08% |
| 3 | BlackRock, Inc. | 118K | $244.4M | +4.0% | 4.759% | 0.00% |
| 4 | River Road Asset Management, LLC | 116K | $240.3M | -3.9% | 4.679% | 2.67% |
| 5 | VANGUARD PORTFOLIO MANAGEMENT LLC | 112K | $232.2M | -3.1% | 4.521% | 0.01% |
| 6 | VANGUARD CAPITAL MANAGEMENT LLC | 107K | $222.8M | -1.5% | 4.340% | 0.00% |
| 7 | FULLER & THALER ASSET MANAGEMENT, INC. | 102K | $211.3M | -2.5% | 4.114% | 0.58% |
| 8 | COOKE & BIELER LP | 85K | $176.5M | -18.8% | 3.437% | 2.04% |
| 9 | Wallace Capital Management Inc. | 80K | $166.0M | +1.6% | 3.233% | 18.20% |
| 10 | FIDUCIARY MANAGEMENT INC /WI/ | 67K | $138.0M | -21.8% | 2.687% | 1.96% |
| 11 | GENDELL JEFFREY L | 59K | $122.8M | +56.7% | 2.392% | 1.08% |
| 12 | Boston Partners | 56K | $115.3M | -3.3% | 2.244% | 0.10% |
| 13 | LONDON CO OF VIRGINIA | 54K | $112.1M | -5.4% | 2.181% | 0.64% |
| 14 | STATE STREET CORP | 50K | $104.2M | +2.2% | 2.029% | 0.00% |
| 15 | GEODE CAPITAL MANAGEMENT, LLC | 49K | $102.5M | +17.3% | 1.995% | 0.01% |
| 16 | MORGAN STANLEY | 47K | $97.2M | -21.0% | 1.892% | 0.01% |
| 17 | REINHART PARTNERS, LLC. | 44K | $92.3M | +19.0% | 1.796% | 2.11% |
| 18 | AMERICAN CENTURY COMPANIES INC | 31K | $64.5M | +274.4% | 1.256% | 0.03% |
| 19 | NORGES BANK | 28K | $58.0M | — | 1.129% | 0.01% |
| 20 | Cannell & Spears LLC | 28K | $57.2M | -1.6% | 1.114% | 1.02% |
| 21 | BANK OF AMERICA CORP /DE/ | 25K | $51.9M | -11.7% | 1.011% | 0.00% |
| 22 | CHARLES SCHWAB INVESTMENT MANAGEMENT INC | 24K | $48.7M | -3.0% | 0.949% | 0.01% |
| 23 | Mraz, Amerine & Associates, Inc. | 22K | $46.1M | +0.2% | 0.897% | 6.61% |
| 24 | Allspring Global Investments Holdings, LLC | 18K | $37.4M | -2.7% | 0.732% | 0.06% |
| 25 | Gotham Asset Management, LLC | 18K | $37.2M | +98.3% | 0.724% | 0.09% |
denotes a marquee investor (Buffett, Burry, ARK, Tiger Global, Pershing Square, Baupost and other widely-followed managers). “% of Fund” shows how much of that investor’s total 13F portfolio is invested in WTM — a direct measure of their conviction.
Filings activity in WTM during Q2 2026, grouped by how each filer changed its position.
8 quarters of 13F filings · Δ columns show change vs prior quarter
| Quarter | Inst. Holders | Δ Holders | Ownership % | Δ Ownership | Total 13F Value | Δ Value |
|---|---|---|---|---|---|---|
| Q2 2026 | 358 | 1.4% | 88.83% | +3.13 pp | $4.36B | 5.2% |
| Q1 2026 | 363 | +4.0% | 85.70% | 0.76 pp | $4.60B | +3.9% |
| Q4 2025 | 349 | +5.8% | 86.46% | 0.43 pp | $4.43B | +20% |
| Q3 2025 | 330 | +2.2% | 86.89% | +0.19 pp | $3.67B | 5.7% |
| Q2 2025 | 323 | +1.9% | 86.70% | 4.84 pp | $3.89B | 4.4% |
| Q1 2025 | 317 | 1.2% | 91.54% | +5.47 pp | $4.07B | 0.9% |
| Q4 2024 | 321 | +7.4% | 86.07% | +2.99 pp | $4.11B | +19% |
| Q3 2024 | 299 | — | 83.08% | — | $3.46B | — |
Source: SEC 13F institutional filings. Ownership % requires market cap data and will show once linked. Δ columns compare to the immediately prior filed quarter.
Quick answers to the most common questions about buying WTM stock.
Based on Q2 2026 13F filings, institutional ownership of White Mountains Insurance Group, Ltd. stands at 88.8%, held across 358 reporting institutions.
DIMENSIONAL FUND ADVISORS LP is the largest reported institutional holder of WTM, with approximately 158,954 shares worth $0.33B as of Q2 2026.
No marquee "smart money" managers (Berkshire, Burry, ARK, Tiger Global, Pershing Square, Baupost, etc.) currently appear among the top 25 institutional holders of WTM.
Our composite Smart Money Score for WTM is 41 out of 100 (Neutral). It combines net institutional buying activity, ownership shift, marquee investor presence, and holder-count growth.
33 institutions opened new positions in WTM during Q2 2026, while 41 fully exited. 66 added to existing positions and 245 trimmed.
WTM institutional ownership rose by 3.13 percentage points quarter-over-quarter, with a net change of -5 holders.
The top 10 institutions account for 50.7% of all reported 13F value in WTM, and the top 25 account for 77.0%.
All data is sourced from SEC Form 13F filings, which institutional investment managers with at least $100M in assets are required to file each quarter. We process every 13F filing from EDGAR and recompute the aggregates after each cycle. Insider transactions are sourced from Form 4 filings.
White Mountains Insurance Group, Ltd. (WTM) Institutional Ownership