Security Snapshot

WHITE MOUNTAINS INSURANCE GROUP LTD - Common Stock (WTM) Institutional Ownership

CUSIP: G9618E107

13F Institutional Holders and Ownership History from Q1 2014 to Q1 2026

Latest Period

Q4 2025

Institutions Reporting

352

Shares (Excl. Options)

2,249,077

Price

$2078.03

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Type / Class
Equity / Common Stock
Symbol
WTM on NYSE
Shares outstanding
2,560,567
Price per share
$2196.96
All holders as of 31 Dec 2025
Q4 2025
Total 13F shares
2,249,077
Total reported value
$4,672,654,306
% of total 13F portfolios
0.01%
Share change
-82,194
Value change
-$163,321,805
Number of holders
352
Price from insider filings
$2196.96
Reported Shares, Excluding Options vs Price
Reported Value, Excluding Options
Total Investors

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Quick Takeaways

  • WTM - WHITE MOUNTAINS INSURANCE GROUP LTD - Common Stock is tracked under CUSIP G9618E107.
  • 352 institutions reported positions in Q4 2025.
  • 2 significant owners is listed from Schedule 13D/13G reporting.

What Changed

  • Holder count moved from 352 to 26 between Q4 2025 and Q1 2026.
  • Reported value moved from $4,672,654,306 to $101,722,652.

Why This Matters

  • 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.

Source Evidence

Source: SEC Form 13F

Latest holder context comes from 352 institutions filings for Q4 2025.

Open SEC Evidence

Investment Quick Answers

What is CUSIP G9618E107?
CUSIP G9618E107 identifies WTM - WHITE MOUNTAINS INSURANCE GROUP LTD - Common Stock in SEC 13F datasets.

Where can I see the latest institutional holders?
Review the Q4 2025 holders report and the ownership history table below.

Significant Owners of WHITE MOUNTAINS INSURANCE GROUP LTD - Common Stock (WTM) based on Schedule 13D/G filings

Filer Ownership Change % Holdings Value Net Change Nb Shares Change % Reporting Name Report Period
Neuberger Berman Group LLC 5.1% $269,424,928 129,654 Neuberger Berman Group LLC 31 Dec 2025
MORGAN STANLEY 3% -44% $158,207,684 -$114,965,582 76,817 -42% Morgan Stanley 31 Dec 2025

As of 31 Dec 2025, 352 institutional investors reported holding 2,249,077 shares of WHITE MOUNTAINS INSURANCE GROUP LTD - Common Stock (WTM). This represents 88% of the company’s total 2,560,567 outstanding shares.

Top 25 Institutional Shareholders

The largest institutional shareholders of WHITE MOUNTAINS INSURANCE GROUP LTD - Common Stock (WTM) together control 70% of the company’s outstanding shares — a level of ownership often associated with strong institutional conviction and long‑term capital commitment.

Institution Ownership % Shares Held Share Change % Portfolio % Holdings Value
VANGUARD GROUP INC 9.2% 235,698 -4.6% 0.01% $489,787,515
DIMENSIONAL FUND ADVISORS LP 6.1% 156,604 -0.39% 0.07% $325,427,647
NEUBERGER BERMAN GROUP LLC 5.1% 129,654 +13% 0.2% $269,424,901
River Road Asset Management, LLC 4.7% 120,880 +10% 2.8% $251,192,266
BlackRock, Inc. 4.4% 112,289 -0.26% 0% $233,341,023
FULLER & THALER ASSET MANAGEMENT, INC. 4.2% 108,172 +0.07% 0.76% $224,785,147
COOKE & BIELER LP 4.2% 106,579 -1.2% 2.3% $221,474,359
FIDUCIARY MANAGEMENT INC /WI/ 3.5% 90,333 -4.3% 2.1% $187,714,684
MORGAN STANLEY 3.2% 82,151 -41% 0.01% $170,715,859
Wallace Capital Management Inc. 3.1% 80,347 -1.4% 20% $166,963,084
Boston Partners 3% 76,911 -8.9% 0.17% $159,727,916
LONDON CO OF VIRGINIA 2.3% 58,697 -12% 0.7% $121,996,162
STATE STREET CORP 2% 50,663 -6.9% 0% $105,279,234
T. Rowe Price Investment Management, Inc. 1.7% 44,560 -6.7% 0.06% $92,598,000
REINHART PARTNERS, LLC. 1.7% 43,973 +5.7% 2.7% $91,413,050
GEODE CAPITAL MANAGEMENT, LLC 1.6% 41,518 -1.4% 0.01% $86,296,476
LORD, ABBETT & CO. LLC 1.3% 33,796 -8.5% 0.22% $70,229,000
GENDELL JEFFREY L 1.3% 32,520 1.2% $67,577,536
NORGES BANK 1.3% 32,184 0.01% $66,879,318
SOUTHEASTERN ASSET MANAGEMENT INC/TN/ 1.2% 31,652 0% 2.9% $65,773,805
BANK OF AMERICA CORP /DE/ 1.1% 28,809 -26% 0% $59,866,018
Cannell & Spears LLC 1.1% 28,115 -0.61% 1.1% $58,422,970
RAYMOND JAMES FINANCIAL INC 0.94% 23,969 -18% 0.02% $49,808,327
CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.91% 23,238 -4.1% 0.01% $48,289,261
Mraz, Amerine & Associates, Inc. 0.88% 22,629 +0.1% 7% $47,024,139

Institutional Holders of WHITE MOUNTAINS INSURANCE GROUP LTD - Common Stock (WTM) across Reporting Periods

Period Reported Shares, Excl. Options Value, Excl. Options Value Change Price (Median) Investors
2026 Q1 46,292 $101,722,652 -$13,430,567 $2196.96 26
2025 Q4 2,249,077 $4,672,654,306 -$163,321,805 $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
2019 Q4 2,742,766 $3,059,658,174 -$32,860,239 $1115.51 252
2019 Q3 2,774,124 $2,995,831,040 -$26,027,851 $1080.00 248
2019 Q2 2,801,619 $2,861,785,183 +$20,334,731 $1021.44 249
2019 Q1 2,806,019 $2,596,957,316 +$39,478,200 $925.48 242
2018 Q4 2,767,043 $2,373,366,225 -$10,445,538 $857.69 242
2018 Q3 2,774,074 $2,596,081,055 -$16,819,815 $935.86 238
2018 Q2 2,821,255 $2,557,740,601 -$326,875,489 $906.61 227
2018 Q1 3,186,982 $2,621,416,419 +$51,033,745 $822.52 229
2017 Q4 3,117,597 $2,653,931,973 +$4,187,400 $851.28 213
2017 Q3 3,103,410 $2,659,778,464 -$624,624,357 $857.00 193
2017 Q2 3,833,182 $3,329,607,785 +$10,674,059 $868.63 205
2017 Q1 3,828,423 $3,367,813,853 +$214,197,149 $879.88 199
2016 Q4 3,763,782 $3,146,741,237 -$19,888,770 $836.05 202
2016 Q3 3,764,024 $3,123,923,790 -$325,244,808 $830.00 187
2016 Q2 4,155,506 $3,498,928,866 -$387,838,025 $842.00 196
2016 Q1 4,618,624 $3,706,750,980 -$156,294,392 $802.60 192
2015 Q4 4,830,375 $3,510,774,031 -$61,612,545 $726.81 193
2015 Q3 4,914,148 $3,672,335,331 -$65,889,466 $747.30 180
2015 Q2 5,053,603 $3,309,742,925 +$11,425,292 $654.94 170
2015 Q1 5,035,592 $3,446,379,757 +$9,562,577 $684.52 173
2014 Q4 5,026,289 $3,167,551,783 -$33,724,059 $630.11 179
2014 Q3 5,073,465 $3,196,689,910 -$68,364,237 $630.07 165
2014 Q2 5,186,143 $3,155,470,676 +$20,361,781 $608.44 178
2014 Q1 5,149,788 $3,089,286,263 -$7,682,092 $599.90 182

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