Latest Period
Q1 2026
Security Snapshot
WHITE MOUNTAINS INSURANCE GROUP LTD - COMMON (WTM) Institutional Ownership
CUSIP: G9618E107
13F Institutional Holders and Ownership History from Q1 2014 to Q1 2026
Institutions Reporting
365
Shares (Excl. Options)
2,208,101
Price
$2196.96
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- Security type / class
- Equity / COMMON
- Symbol
- WTM on NYSE
- All holders as of 31 Mar 2026
- Q1 2026
- Total 13F shares
- 2,208,101
- Total 13F value
- $4,850,928,905
- Portfolio coverage rank
- 0.01%
- Share change
- -45,534
- Value change
- -$95,031,505
- Number of holders
- 365
- Shares outstanding
- 2,481,286
- SEC-reported price per share
- $2146.85
- Insider filing price
- $2146.85
Latest holder snapshot
5 signals
Issuer context
Names, identifiers, and filing context for this profile.
3 identity fields
13F Shares, Excluding Options vs Price
13F Value, Excluding Options
Total Investors
Key facts
- WTM - WHITE MOUNTAINS INSURANCE GROUP LTD - COMMON is tracked under CUSIP G9618E107.
- 365 institutions reported positions in Q1 2026.
- 3 significant owners is listed from Schedule 13D/13G reporting.
Change
- Holder count moved from 352 to 365 between Q4 2025 and Q1 2026.
- SEC-reported value moved from $4,672,654,306 to $4,850,928,905.
Research use
- You can quickly see who holds this security, then open quarter and manager detail pages for full evidence.
- 13F and Schedule 13D/13G sections are kept together so you can cross-check institutional and beneficial ownership context.
Evidence
Source: SEC Form 13F
Open SEC evidence
Latest holder context comes from 365 institutions filings for Q1 2026.
Security key
G9618E107
Latest holder period
Q1 2026
13F holders
365
13D/G owners
3
CIK / CUSIP context first
Open Q1 2026 holders
WTM full holder history
WHITE MOUNTAINS INSURANCE GROUP LTD SEC filings
WHITE MOUNTAINS INSURANCE GROUP LTD company facts
WHITE MOUNTAINS INSURANCE GROUP LTD insider transactions
WHITE MOUNTAINS INSURANCE GROUP LTD 13D/G history
Broader feeds
Recent Quarterly Holder Reports
Open recent reporting periods for CUSIP G9618E107:
13D/G owners
Significant owners
Large-stake holder rows connected to Schedule 13D/G evidence.
Rows
3
Security
WTM
| Filer | Ownership | Change % | Holdings Value | Net Change | Nb Shares | Change % | Reporting Name | Report Period |
|---|---|---|---|---|---|---|---|---|
| VANGUARD CAPITAL MANAGEMENT LLC | 5.2% | $281,195,565 | 127,993 | Vanguard Capital Management | 31 Mar 2026 | |||
| Neuberger Berman Group LLC | 4.9% | -4% | $267,113,024 | -$17,731,667 | 121,583 | -6.2% | Neuberger Berman Group LLC | 30 Apr 2026 |
| MORGAN STANLEY | 3% | -44% | $158,207,684 | -$114,965,582 | 76,817 | -42% | Morgan Stanley | 31 Dec 2025 |
As of 31 Mar 2026, 365 institutional investors reported holding 2,208,101 shares of WHITE MOUNTAINS INSURANCE GROUP LTD - COMMON (WTM). This represents 89% of the company’s total 2,481,286 outstanding shares.
13F concentration
Top 25 institutional shareholders
Largest 13F positions for this security by reported shares and value.
Top holder share
67%
| Institution | Ownership % | Shares Held | Share Change % | Portfolio % | Holdings Value |
|---|---|---|---|---|---|
| DIMENSIONAL FUND ADVISORS LP | 6.3% | 156,618 | +0.01% | 0.07% | $344,084,166 |
| NEUBERGER BERMAN GROUP LLC | 5% | 124,715 | -3.8% | 0.21% | $273,993,893 |
| River Road Asset Management, LLC | 4.9% | 120,519 | -0.3% | 3% | $264,775,422 |
| VANGUARD PORTFOLIO MANAGEMENT LLC | 4.7% | 115,553 | 0% | 0.01% | $253,865,319 |
| BlackRock, Inc. | 4.6% | 113,328 | +0.93% | 0% | $248,976,061 |
| VANGUARD CAPITAL MANAGEMENT LLC | 4.4% | 109,157 | 0% | 0.01% | $239,813,563 |
| COOKE & BIELER LP | 4.2% | 104,857 | -1.6% | 2.6% | $230,366,635 |
| FULLER & THALER ASSET MANAGEMENT, INC. | 4.2% | 104,561 | -3.3% | 0.77% | $229,715,563 |
| FIDUCIARY MANAGEMENT INC /WI/ | 3.4% | 85,066 | -5.8% | 2.3% | $186,886,599 |
| Wallace Capital Management Inc. | 3.2% | 78,795 | -1.9% | 20% | $173,109,162 |
| MORGAN STANLEY | 2.4% | 59,295 | -28% | 0.01% | $130,273,576 |
| Boston Partners | 2.3% | 57,459 | -25% | 0.13% | $126,222,446 |
| LONDON CO OF VIRGINIA | 2.3% | 57,131 | -2.7% | 0.77% | $125,537,405 |
| STATE STREET CORP | 2% | 49,158 | -3% | 0% | $107,998,160 |
| GEODE CAPITAL MANAGEMENT, LLC | 1.7% | 42,119 | +1.4% | 0.01% | $92,559,204 |
| T. Rowe Price Investment Management, Inc. | 1.7% | 41,513 | -6.8% | 0.06% | $91,203,000 |
| GENDELL JEFFREY L | 1.5% | 37,814 | +16% | 1.1% | $83,075,845 |
| REINHART PARTNERS, LLC. | 1.5% | 37,374 | -15% | 2.4% | $82,148,044 |
| LORD, ABBETT & CO. LLC | 1.3% | 33,110 | -2% | 0.24% | $72,741,000 |
| BANK OF AMERICA CORP /DE/ | 1.1% | 28,358 | -1.6% | 0% | $62,301,392 |
| Cannell & Spears LLC | 1.1% | 28,027 | -0.31% | 1.2% | $61,573,306 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC | 0.98% | 24,241 | +4.3% | 0.01% | $53,256,507 |
| RAYMOND JAMES FINANCIAL INC | 0.97% | 23,951 | -0.08% | 0.02% | $52,619,460 |
| Mraz, Amerine & Associates, Inc. | 0.89% | 22,179 | -2% | 7.2% | $48,726,795 |
| SOUTHEASTERN ASSET MANAGEMENT INC/TN/ | 0.76% | 18,864 | -40% | 2% | $41,443,454 |
Quarter history
Institutional holders across reporting periods
Holder count, reported shares/value, and median price by quarter.
Periods
49
Latest
Q1 2026
Rows shown
1-25 of 49
| Period | 13F Shares, Excl. Options | Value, Excl. Options | Value Change | Price (Median) | Investors |
|---|---|---|---|---|---|
| 2026 Q1 | 2,208,101 | $4,850,928,905 | -$95,031,505 | $2196.96 | 365 |
| 2025 Q4 | 2,249,077 | $4,672,654,306 | -$163,522,387 | $2078.03 | 352 |
| 2025 Q3 | 2,328,196 | $3,892,926,495 | +$6,813,958 | $1671.52 | 337 |
| 2025 Q2 | 2,319,591 | $4,164,032,974 | +$75,999,210 | $1795.72 | 323 |
| 2025 Q1 | 2,276,772 | $4,380,930,355 | -$297,813 | $1925.81 | 318 |
| 2024 Q4 | 2,275,935 | $4,425,642,568 | +$63,434,905 | $1945.06 | 322 |
| 2024 Q3 | 2,225,354 | $3,778,177,309 | -$51,170,618 | $1696.20 | 303 |
| 2024 Q2 | 2,278,803 | $4,139,897,835 | +$36,191,894 | $1817.45 | 306 |
| 2024 Q1 | 2,257,876 | $4,050,627,891 | +$44,925,950 | $1794.30 | 300 |
| 2023 Q4 | 2,272,473 | $3,420,895,166 | +$448,401 | $1505.01 | 295 |
| 2023 Q3 | 2,270,617 | $3,396,009,565 | +$34,549,405 | $1495.69 | 272 |
| 2023 Q2 | 2,245,483 | $3,125,347,144 | -$4,780,701 | $1388.91 | 258 |
| 2023 Q1 | 2,244,965 | $3,093,422,937 | -$11,530,148 | $1377.49 | 261 |
| 2022 Q4 | 2,264,311 | $3,203,221,874 | +$152,825,819 | $1414.33 | 263 |
| 2022 Q3 | 2,283,636 | $2,976,640,572 | -$484,484,653 | $1303.02 | 246 |
| 2022 Q2 | 2,659,641 | $3,314,994,939 | -$39,000,392 | $1246.12 | 258 |
| 2022 Q1 | 2,663,943 | $3,019,127,305 | +$49,978,796 | $1136.23 | 242 |
| 2021 Q4 | 2,675,937 | $2,714,257,113 | -$5,261,729 | $1013.88 | 243 |
| 2021 Q3 | 2,671,067 | $2,857,370,130 | -$38,324,659 | $1069.62 | 230 |
| 2021 Q2 | 2,711,945 | $3,113,296,748 | +$8,100,205 | $1148.03 | 232 |
| 2021 Q1 | 2,708,626 | $3,023,933,244 | +$25,864,750 | $1114.90 | 245 |
| 2020 Q4 | 2,696,102 | $2,697,911,953 | -$1,365,215 | $1000.00 | 234 |
| 2020 Q3 | 2,698,359 | $2,102,120,394 | -$18,772,862 | $779.00 | 216 |
| 2020 Q2 | 2,720,045 | $2,415,355,341 | -$2,045,819 | $887.97 | 204 |
| 2020 Q1 | 2,720,561 | $2,475,614,880 | -$33,457,363 | $910.00 | 226 |