WHITE MTNS INS GROUP LTD (WTM) Institutional Shareholders
WHITE MTNS INS GROUP LTD (WTM) is currently reported in institutional portfolios tracked by InsiderSet based on the latest available SEC Form 13F filings for the quarter ended June 30, 2026. The institutional investors covered on this page collectively reported approximately $4.57B in WTM holdings during the latest filing period.
Dimensional Fund Advisors Lp is currently the largest disclosed institutional shareholder of WTM tracked by InsiderSet, reporting ownership valued at approximately $329.58M in its June 30, 2026 SEC Form 13F filing. Based on current market prices and the latest disclosed share count, the position is now estimated to be worth approximately $327.18M, representing an estimated loss of -0.73% since the filing period.
The top 10 institutional shareholders tracked on this page collectively account for approximately 48% of the total disclosed WTM value among the investors covered in this analysis. Major shareholders include Dimensional Fund Advisors Lp, Neuberger Berman Group Llc, Blackrock, Inc., and several other long-term asset managers with concentrated positions in WHITE MTNS INS GROUP LTD (WTM).
This page ranks the largest institutional WTM shareholders using publicly disclosed SEC Form 13F data, including reported values, estimated current holding values, portfolio allocation percentages, ownership concentration metrics, and historical holding changes across major hedge funds and investment firms.
Institutional Holders
344
Total Reported Value
$4.57B
Largest Holder
Dimensional Fund Advisors Lp
Largest Position
$329.58M
Insider Transactions (90d)
1
Latest Filing Quarter
Q2 2026
New Institutional Positions
35
Funds Exiting Positions
0
| Name | Investor/Manager | Portfolio % | Quantity | Reported Balance | Current Estimated Value | Gain/loss Since Filing | Estimated Portfolio Performance |
|---|---|---|---|---|---|---|---|
| Dimensional Fund Advisors Lp | 0.06% | 158,954 | $329,577,765 | $327,178,197 | -$2,399,568 | -0.73% | |
| Neuberger Berman Group Llc | 0.16% | 119,141 | $247,025,783 | $245,230,303 | -$1,795,480 | -0.73% | |
| Blackrock, Inc. | 0.00% | 117,849 | $244,347,011 | $242,570,954 | -$1,776,057 | -0.73% | |
| River Road Asset Management, Llc | 2.67% | 115,880 | $240,264,433 | $238,518,122 | -$1,746,311 | -0.73% | |
| Vanguard Portfolio Management Llc | 0.01% | 111,969 | $232,155,405 | $230,468,032 | -$1,687,373 | -0.73% | |
| Vanguard Capital Management Llc | 0.00% | 107,479 | $222,845,884 | $221,226,175 | -$1,619,709 | -0.73% | |
| Fuller & Thaler Asset Management, Inc. | 0.58% | 101,892 | $211,260,919 | $209,726,341 | -$1,534,578 | -0.73% | |
| Cooke & Bieler Lp | 2.04% | 85,120 | $176,486,957 | $175,204,198 | -$1,282,759 | -0.73% | |
| Wallace Capital Management Inc. | 18.20% | 80,067 | $166,009,833 | $164,803,507 | -$1,206,326 | -0.73% | |
| Fiduciary Management Inc | 1.96% | 66,550 | $137,984,104 | $136,981,196 | -$1,002,908 | -0.73% | |
| Gendell Jeffrey L | 1.11% | 59,243 | $122,833,844 | $121,941,052 | -$892,792 | -0.73% | |
| Boston Partners | 0.10% | 55,569 | $115,277,291 | $114,378,784 | -$898,507 | -0.78% | |
| London Co Of Virginia | 0.64% | 54,025 | $112,075,761 | $111,200,738 | -$875,023 | -0.78% | |
| State Street Corp | 0.00% | 50,257 | $104,202,361 | $103,444,988 | -$757,373 | -0.73% | |
| Geode Capital Management, Llc | 0.01% | 49,412 | $102,474,687 | $101,705,708 | -$768,979 | -0.75% | |
| Morgan Stanley | 0.01% | 46,866 | $97,175,344 | $96,465,225 | -$710,119 | -0.73% | |
| Reinhart Partners, Llc. | 2.11% | 44,480 | $92,265,213 | $91,554,074 | -$711,139 | -0.77% | |
| T. Rowe Price Investment Management, Inc. | 0.05% | 34,237 | $70,987,000 | $70,470,702 | -$516,298 | -0.73% | |
| Lord, Abbett & Co. Llc | 0.19% | 32,829 | $68,067,000 | $67,572,587 | -$494,413 | -0.73% | |
| American Century Companies Inc | 0.03% | 31,108 | $64,499,016 | $64,030,219 | -$468,797 | -0.73% | |
| Norges Bank | 0.01% | 27,956 | $57,963,691 | $57,542,394 | -$421,297 | -0.73% | |
| Cannell & Spears Llc | 1.02% | 27,577 | $57,177,034 | $56,762,291 | -$414,743 | -0.73% | |
| Bank Of America Corp | 0.00% | 25,028 | $51,892,804 | $51,515,633 | -$377,171 | -0.73% | |
| Charles Schwab Investment Management Inc | 0.01% | 23,505 | $48,735,032 | $48,380,812 | -$354,220 | -0.73% | |
| Mraz, Amerine & Associates, Inc. | 6.61% | 22,218 | $46,066,975 | $45,731,754 | -$335,221 | -0.73% | |
| Allspring Global Investments Holdings, Llc | 0.06% | 18,116 | $37,392,149 | $37,288,525 | -$103,624 | -0.28% | |
| Gotham Asset Management, Llc | 0.09% | 17,940 | $37,196,617 | $36,926,261 | -$270,356 | -0.73% | |
| Brown Advisory Inc | 0.06% | 17,722 | $36,745,806 | $36,477,547 | -$268,259 | -0.73% | |
| Jane Street Group, Llc | 0.02% | 17,226 | $35,716,216 | $35,456,620 | -$259,596 | -0.73% | |
| Longleaf Partners | Mason Hawkins | 1.85% | 17,104 | $35,463,263 | $35,205,505 | -$257,758 | -0.73% |
| Ubs Group Ag | 0.01% | 16,198 | $33,584,772 | $33,340,667 | -$244,105 | -0.73% | |
| Vanguard Fiduciary Trust Co | 0.01% | 15,319 | $31,762,261 | $31,531,404 | -$230,857 | -0.73% | |
| Boussard & Gavaudan Investment Management Llp | 2.97% | 13,975 | $30,968,600 | $28,765,022 | -$2,203,578 | -7.12% | |
| Raymond James Financial Inc | 0.01% | 14,833 | $30,754,659 | $30,531,061 | -$223,598 | -0.73% | |
| Northern Trust Corp | 0.00% | 14,571 | $30,211,365 | $29,991,781 | -$219,584 | -0.73% | |
| Wellington Management Group Llp | 0.01% | 14,532 | $30,130,503 | $29,911,506 | -$218,997 | -0.73% | |
| Envestnet Asset Management Inc | 0.01% | 13,838 | $28,691,176 | $28,483,032 | -$208,144 | -0.73% | |
| Quantinno Capital Management Lp | 0.03% | 12,624 | $26,174,512 | $25,984,232 | -$190,280 | -0.73% | |
| Elkhorn Partners Limited Partnership | 21.89% | 12,320 | $25,544,165 | $25,358,502 | -$185,663 | -0.73% | |
| Horizon Kinetics Asset Management Llc | 0.29% | 12,206 | $25,307,802 | $25,123,854 | -$183,948 | -0.73% | |
| Goldman Sachs Group Inc | 0.00% | 12,151 | $25,193,682 | $25,010,646 | -$183,036 | -0.73% | |
| Victory Capital Management Inc | 0.01% | 10,684 | $22,152,098 | $21,991,091 | -$161,007 | -0.73% | |
| First Trust Advisors Lp | 0.01% | 10,604 | $21,986,231 | $21,826,425 | -$159,806 | -0.73% | |
| Qube Research & Technologies Ltd | 0.02% | 9,673 | $20,055,901 | $19,910,129 | -$145,772 | -0.73% | |
| Speece Thorson Capital Group Inc | 4.08% | 9,215 | $19,106,000 | $18,967,419 | -$138,581 | -0.73% | |
| Wells Fargo & Company/Mn | 0.00% | 8,710 | $18,058,335 | $17,927,967 | -$130,368 | -0.72% | |
| Bank Of New York Mellon Corp | 0.00% | 8,412 | $17,440,426 | $17,314,588 | -$125,838 | -0.72% | |
| Ubs Am, A Distinct Business Unit Of Ubs Asset Management Americas Llc | 0.00% | 7,826 | $17,193,410 | $16,108,412 | -$1,084,998 | -6.31% | |
| Sei Investments Co | 0.01% | 8,108 | $16,810,842 | $16,688,859 | -$121,983 | -0.73% | |
| Gw&K Investment Management, Llc | 0.13% | 7,839 | $16,253,000 | $16,135,170 | -$117,830 | -0.72% |
Frequently asked questions about WTM
Who owns the most WTM stock?
The largest holders of WTM are typically major institutional investors such as asset managers and hedge funds reporting on Form 13F. The table above ranks tracked superinvestors by reported position size using the latest available filings for WHITE MTNS INS GROUP LTD (WTM).
Is WTM widely held by superinvestors?
Many widely followed stocks like WTM appear across numerous superinvestor portfolios because of liquidity, index inclusion, and fundamentals. The holder count and table above show how broadly WTM is represented among the institutional managers we track.
What do “Current Estimated Value”, “Gain/loss Since Filing”, and “Estimated Portfolio Performance” mean?
Current Estimated Value is reported share quantity from the latest 13F times our most recent split-adjusted U.S. session close. Gain/loss Since Filing is that estimate minus the reported 13F dollar value; Estimated Portfolio Performance is that difference as a percent of the reported value. Green means the estimate is above the filing value; red means below (not purchase cost). If many filers share the same implied filing price per share, the performance % may match across rows. These are not official fund marks or live quotes.