White Mountains Insurance Group Ltd. (WTM)

NYSE: WTM · Fire, Marine & Casualty Insurance · Hanover, NH · filing with the SEC since 1994

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Grade6.3

◀ Past 6.6● Present 6.4▶ Future 5.9

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Who owns White Mountains Insurance Group Ltd.

As filed with the SEC

Holders of 5% or more

Vanguard Capital Management holds 5.18% of Common Stock, as its SCHEDULE 13G filed Apr 30, 2026 says.

Directors and officers

report now, of 29 people on the record since 2006. Their holdings as a group are not read here.

Institutions as a whole

n/a

The record does not read the share held by managers that file Form 13F, so none is printed and no split of the rest is estimated. What it holds is the 1 named at left.

Holders of 5% or moreshare of the class, as filed

Vanguard Capital Management

SCHEDULE 13G · filed Apr 30, 2026 · Common Stock

5.18%

Neuberger Berman Group LLC

SCHEDULE 13G/A · filed May 7, 2026 · COMMON · reported falling below 5%, from 5.1% in Feb 5, 2026

under 5%

Morgan Stanley

SCHEDULE 13G/A · filed Feb 12, 2026 · Common Stock · reported falling below 5%, from 5.2% in Nov 7, 2025

under 5%

The Vanguard Group

SCHEDULE 13G/A · filed Mar 27, 2026 · Common Stock · reported falling below 5%

under 5%

What WTM reports owning in othersstakes of 5% or more, and other ties

MediaAlpha, Inc. MAX

SCHEDULE 13D/A · filed May 1, 2026 · Class A Common Stock, par value $0.01 per share

33%

Other ties the annual report names

Outrigger Re Ltd

An entity · legal entity · owns, named in the 10-K filed Feb 27, 2026

Subsidiary - Ark Insurance Holdings Limited