13F Insight
DOSSIER · 13F Holders · Q2 2026

WHITE MTNS INS GROUP LTD

372 institutions still hold WHITE MTNS INS GROUP LTD as of Q2 2026. Tracked across SEC 13F-HR filings, with insider and 13D/G activity surfaced alongside.

CUSIP G9618E107·372 13F holders·last filed Jun 30, 2026
Market cap
—
13F value held
$3.2B
visible holders
Holders
372
filers reporting
Concentration
10.36%
DIMENSIONAL FUND ADVISORS LP #1
top holder share
AI Holders Summary · Q2 2026

372 institutions reported WHITE MTNS INS GROUP LTD in Q2 2026. DIMENSIONAL FUND ADVISORS LP leads at 10.4% of the visible book.

Top holders

Sorted by position value. Source: SEC EDGAR 13F-HR filings.

#HolderValueShares% port.Quarter
01
DIMENSIONAL FUND ADVISORS LP
CIK 0000354204· Quasi-passive
$330M159K0.06%Q2 202602
Neuberger Berman Group LLC
CIK 0001465109
$247M119K0.16%Q2 202603
BlackRock, Inc.
CIK 0002012383
$244M118K0.00%Q2 202604
River Road Asset Management, LLC
CIK 0001341401
$240M116K2.67%Q2 202605
Vanguard Portfolio Management
CIK 0002100121· Index
$232M112K0.01%Q2 202606
VANGUARD CAPITAL MANAGEMENT LLC
CIK 0002100119· Index
$223M107K0.00%Q2 202607
FULLER & THALER ASSET MANAGEMENT, INC.
CIK 0001082327
$211M102K0.58%Q2 202608
COOKE & BIELER LP
CIK 0000024386
$176M85K2.04%Q2 202609
Wallace Capital Management Inc.
CIK 0001459754
$166M80K18.20%Q2 202610
FIDUCIARY MANAGEMENT INC /WI/
CIK 0000764532
$138M67K1.96%Q2 202611
GENDELL JEFFREY L
CIK 0001056581
$123M59K1.08%Q2 202612
Boston Partners
CIK 0001386060
$115M56K0.10%Q2 202613
LONDON CO OF VIRGINIA
CIK 0001259887
$112M54K0.64%Q2 202614
STATE STREET CORP
CIK 0000093751
$104M50K0.00%Q2 202615
GEODE CAPITAL MANAGEMENT, LLC
CIK 0001214717· Index
$102M49K0.01%Q2 202616
MORGAN STANLEY
CIK 0000895421
$97M47K0.01%Q2 202617
REINHART PARTNERS, LLC.
CIK 0001080298
$92M44K2.11%Q2 202618
T. Rowe Price Investment Management, Inc.
CIK 0001897612
$91M42K0.06%Q1 202619
LORD, ABBETT & CO. LLC
CIK 0000728100
$73M33K0.24%Q1 202620
AMERICAN CENTURY COMPANIES INC
CIK 0000748054
$64M31K0.03%Q2 2026
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