White Mountains Insurance Group Ltd

WTM

Exchange: NYSE
Industry: Fire, Marine & Casualty Insurance
SEC CIK: 0000776867

SEC filings (opens in a new tab)

No open-market purchases or sales by White Mountains Insurance Group Ltd insiders were filed in the last 90 days; 356 institutions reported holding it in 13F filings for Q2 2026, worth $4.57B in total; Southeastern Asset Management (Longleaf) is the only superinvestor holding it.

13F holders, Q3 2026

Institutional positions in White Mountains Insurance Group Ltd as of Sep 30, 2026. Investment managers with $100 million or more in US stocks report their long positions on Form 13F within 45 days after each quarter ends. How 13F works

Q3 2026 data is still coming in (13F filing deadline: Nov 16, 2026), so these numbers are incomplete.

Institutional holders: 5; −1 vs. Q2 2026
Shares held: 196; 0 (0.0%) vs. Q2 2026
Total value: $393.3K; −$13.1K (−3.2%) vs. Q2 2026
New holders: 1; 2 more added
Sold out: 2; 1 more reduced

350 institutions that held it in Q2 2026 haven't filed for Q3 2026 yet. Not filing isn't selling, so they aren't counted as sold out or in the changes above.

Compare with Q2 2026: new holders, sold out and not filed yet

Holders and value by quarter

Institutions reporting WTM on Form 13F each quarter since Q1 2021, and the total value they reported. Values are as of each quarter end, so they also move with the share price.

Institutional holders

Value held

Institutions holding WTM and their total value by quarter
Quarter	Holders	Value
Q2 2026	356	$4.57B
Q1 2026	368	$4.86B
Q4 2025	353	$4.67B
Q3 2025	338	$3.89B
Q2 2025	325	$4.17B
Q1 2025	322	$4.44B
Q4 2024	325	$4.43B
Q3 2024	304	$3.78B
Q2 2024	306	$4.14B
Q1 2024	303	$4.06B
Q4 2023	295	$3.42B
Q3 2023	272	$3.40B
Q2 2023	258	$3.13B
Q1 2023	262	$3.09B
Q4 2022	265	$3.20B
Q3 2022	251	$2.98B
Q2 2022	259	$3.32B
Q1 2022	244	$3.09B
Q4 2021	243	$2.71B
Q3 2021	232	$2.86B
Q2 2021	233	$3.11B
Q1 2021	245	$3.02B

Institutions, Q3 2026

Shares, value and share of portfolio for each institution holding White Mountains Insurance Group Ltd; share changes are against Q2 2026.

Institutions holding WTM in Q3 2026
Institution	Shares	Value	% of portfolio	Change in shares	Action
Eastern Bank	100	$200.6K	0.00%	00.0%	Unchanged
Stephenson National Bank & Trust	56	$112.4K	0.03%	−2−3.4%	Reduced
Versant Capital Management, Inc	35	$70.2K	0.01%	+11+45.8%	Added
ZRC Wealth Management, LLC	4	$8.03K	0.00%	+3+300.0%	Added
GoalVest Advisory LLC	1	$2.01K	0.00%	+1	New
Miller Global Investments, LLC	0	$0	0.00%	−12−100.0%	Sold out
Massmutual Trust Co FSB	0	$0	0.00%	−1−100.0%	Sold out
Dimensional Fund Advisors LP	–	–	–	–	Not filed
Neuberger Berman Group LLC	–	–	–	–	Not filed
BlackRock, Inc.	–	–	–	–	Not filed
River Road Asset Management, LLC	–	–	–	–	Not filed
Vanguard Portfolio Management LLC	–	–	–	–	Not filed
Vanguard Capital Management LLC	–	–	–	–	Not filed
Fuller & Thaler Asset Management, Inc.	–	–	–	–	Not filed
Cooke & Bieler LP	–	–	–	–	Not filed
Wallace Capital Management Inc.	–	–	–	–	Not filed
Fiduciary Management Inc	–	–	–	–	Not filed
Gendell Jeffrey L	–	–	–	–	Not filed
Boston Partners	–	–	–	–	Not filed
London Co of Virginia	–	–	–	–	Not filed
State Street Corp	–	–	–	–	Not filed
Geode Capital Management, LLC	–	–	–	–	Not filed
Morgan Stanley	–	–	–	–	Not filed
Reinhart Partners, Inc.	–	–	–	–	Not filed
T. Rowe Price Investment Management, Inc.	–	–	–	–	Not filed
Lord, Abbett & Co. LLC	–	–	–	–	Not filed
American Century Companies Inc	–	–	–	–	Not filed
Norges Bank	–	–	–	–	Not filed
Spears Abacus Advisors LLC	–	–	–	–	Not filed
Bank of America Corp	–	–	–	–	Not filed
Charles Schwab Investment Management Inc	–	–	–	–	Not filed
Mraz, Amerine & Associates, Inc.	–	–	–	–	Not filed
Allspring Global Investments Holdings, LLC	–	–	–	–	Not filed
Gotham Asset Management, LLC	–	–	–	–	Not filed
Brown Advisory Inc	–	–	–	–	Not filed
Jane Street Group, LLC	–	–	–	–	Not filed
Southeastern Asset Management IncSuperinvestorSoutheastern Asset Management (Longleaf)	–	–	–	–	Not filed
UBS Group AG	–	–	–	–	Not filed
Vanguard Fiduciary Trust Co	–	–	–	–	Not filed
Raymond James Financial Inc	–	–	–	–	Not filed
Northern Trust Corp	–	–	–	–	Not filed
Wellington Management Group LLP	–	–	–	–	Not filed
Envestnet Asset Management Inc	–	–	–	–	Not filed
Quantinno Capital Management LP	–	–	–	–	Not filed
Elkhorn Partners Limited Partnership	–	–	–	–	Not filed
Horizon Kinetics Asset Management LLC	–	–	–	–	Not filed
Goldman Sachs Group Inc	–	–	–	–	Not filed
Boussard & Gavaudan Gestion SAS	–	–	–	–	Not filed
Victory Capital Management Inc	–	–	–	–	Not filed
First Trust Advisors LP	–	–	–	–	Not filed
Qube Research & Technologies Ltd	–	–	–	–	Not filed
Speece Thorson Capital Group Inc	–	–	–	–	Not filed
Wells Fargo & Company	–	–	–	–	Not filed
Bank of New York Mellon Corp	–	–	–	–	Not filed
SEI Investments Co	–	–	–	–	Not filed
GW&K Investment Management, LLC	–	–	–	–	Not filed
Thompson Siegel & Walmsley LLC	–	–	–	–	Not filed
Arrowstreet Capital, Limited Partnership	–	–	–	–	Not filed
Citadel Advisors LLC	–	–	–	–	Not filed
Hotchkis & Wiley Capital Management LLC	–	–	–	–	Not filed
Royce & Associates LP	–	–	–	–	Not filed
HRT Financial LP	–	–	–	–	Not filed
D. E. Shaw & Co., Inc.	–	–	–	–	Not filed
Edgestream Partners, L.P.	–	–	–	–	Not filed
JPMorgan Chase & Co	–	–	–	–	Not filed
AQR Capital Management LLC	–	–	–	–	Not filed
California Public Employees Retirement System	–	–	–	–	Not filed
Williams Jones Wealth Management, LLC.	–	–	–	–	Not filed
Swiss National Bank	–	–	–	–	Not filed
Winmill & Co. Inc	–	–	–	–	Not filed
Franklin Resources Inc	–	–	–	–	Not filed
Phocas Financial Corp.	–	–	–	–	Not filed
Rhumbline Advisers	–	–	–	–	Not filed
Creative Planning	–	–	–	–	Not filed
Nuveen, LLC	–	–	–	–	Not filed
Invesco Ltd.	–	–	–	–	Not filed
Lee Danner & Bass Inc	–	–	–	–	Not filed
Ameriprise Financial Inc	–	–	–	–	Not filed
California State Teachers Retirement System	–	–	–	–	Not filed
New York State Common Retirement Fund	–	–	–	–	Not filed
Triad Investment Management	–	–	–	–	Not filed
Vanguard Asset Management, Ltd	–	–	–	–	Not filed
Russell Investments Group, Ltd.	–	–	–	–	Not filed
State Board of Administration of Florida Retirement System	–	–	–	–	Not filed
Price T Rowe Associates Inc	–	–	–	–	Not filed
Legal & General Group Plc	–	–	–	–	Not filed
Robeco Institutional Asset Management B.V.	–	–	–	–	Not filed
Regency Capital Management Inc.	–	–	–	–	Not filed
Davenport & Co LLC	–	–	–	–	Not filed
Bradley Foster & Sargent Inc	–	–	–	–	Not filed
Parsons Capital Management Inc	–	–	–	–	Not filed
Lighthouse Investment Partners, LLC	–	–	–	–	Not filed
Cerity Partners LLC	–	–	–	–	Not filed
Atlantic Union Bankshares Corp	–	–	–	–	Not filed
MML Investors Services, LLC	–	–	–	–	Not filed
Agf Management Ltd	–	–	–	–	Not filed
XTX Topco Ltd	–	–	–	–	Not filed
Toroso Investments, LLC	–	–	–	–	Not filed
Colony Group, LLC	–	–	–	–	Not filed
ExodusPoint Capital Management, LP	–	–	–	–	Not filed