Stock Ownership/WHITE MTNS INS GROUP LTD

WHITE MTNS INS GROUP LTD: Ownership & Insider Activity

Hedge funds and institutional managers reporting a position in WHITE MTNS INS GROUP LTD. Based on the most recent 13F filing from each holder, sourced from SEC EDGAR.

Reported Holders
14
13F filers
Aggregate Value
$160.1M
Across holders
Last Price
—
EOD close
Sector
—
GICS
Quarterly fund activity9 increased4 reduced5 exited
Full exits: Select Equity Group, L.P., RENAISSANCE TECHNOLOGIES LLC, Bridgewater Associates, LP, Ancora Advisors, LLC, MARSHALL WACE, LLP
Institutional Holders of WHITE MTNS INS GROUP LTD
↗
14 holders
Manager⇅Type⇅Shares⇅Market Value▼% of Total⇅% of Portfolio⇅Action⇅QoQ Change⇅Quarter⇅
Gotham Asset Management, LLC
CIK 0001510387
Hedge Fund18K$37.2M23.2%0.1%Added+$18.4MQ2 2026
SOUTHEASTERN ASSET MANAGEMENT INC/TN/
CIK 0000807985
Hedge Fund17K$35.5M22.1%1.8%Reduced$-27.7MQ2 2026
Qube Research & Technologies Ltd
CIK 0001729829
Hedge Fund10K$20.1M12.5%0.0%Added+$17.9MQ2 2026
ARROWSTREET CAPITAL, LIMITED PARTNERSHIP
CIK 0001164508
Hedge Fund7K$15.1M9.4%0.0%Added+$11.1MQ2 2026
CITADEL ADVISORS LLC
CIK 0001423053
Hedge Fund7K$14.8M9.2%0.0%Added+$9.3MQ2 2026
SHAW D E & CO INC
CIK 0001009207
Hedge Fund7K$13.7M8.6%0.0%Reduced$-21.6MQ2 2026
AQR CAPITAL MANAGEMENT LLC
CIK 0001167557
Hedge Fund5K$11.3M7.1%0.0%Reduced+$11.3MQ2 2026
Lighthouse Investment Partners, LLC
CIK 0001600344
Hedge Fund2K$3.9M2.4%0.1%Added—Q2 2026
ExodusPoint Capital Management, LP
CIK 0001736225
Hedge Fund1K$3.0M1.9%0.0%Added—Q2 2026
Walleye Capital LLC
CIK 0001758720
Hedge Fund1K$2.3M1.5%0.0%Added—Q2 2026
Gotham Asset Management, LLCAdded
Hedge Fund
$37.2M· 23.2% of total· 0.1% port· 18K sh· +$18.4M QoQ· Q2 2026
SOUTHEASTERN ASSET MANAGEMENT INC/TN/Reduced
Hedge Fund
$35.5M· 22.1% of total· 1.8% port· 17K sh· $-27.7M QoQ· Q2 2026
Qube Research & Technologies LtdAdded
Hedge Fund
$20.1M· 12.5% of total· 0.0% port· 10K sh· +$17.9M QoQ· Q2 2026
ARROWSTREET CAPITAL, LIMITED PARTNERSHIPAdded
Hedge Fund
$15.1M· 9.4% of total· 0.0% port· 7K sh· +$11.1M QoQ· Q2 2026
CITADEL ADVISORS LLCAdded
Hedge Fund
$14.8M· 9.2% of total· 0.0% port· 7K sh· +$9.3M QoQ· Q2 2026
SHAW D E & CO INCReduced
Hedge Fund
$13.7M· 8.6% of total· 0.0% port· 7K sh· $-21.6M QoQ· Q2 2026
AQR CAPITAL MANAGEMENT LLCReduced
Hedge Fund
$11.3M· 7.1% of total· 0.0% port· 5K sh· +$11.3M QoQ· Q2 2026
Lighthouse Investment Partners, LLCAdded
Hedge Fund
$3.9M· 2.4% of total· 0.1% port· 2K sh· — QoQ· Q2 2026
ExodusPoint Capital Management, LPAdded
Hedge Fund
$3.0M· 1.9% of total· 0.0% port· 1K sh· — QoQ· Q2 2026
Walleye Capital LLCAdded
Hedge Fund
$2.3M· 1.5% of total· 0.0% port· 1K sh· — QoQ· Q2 2026
Squarepoint Ops LLCAdded
Hedge Fund
$1.9M· 1.2% of total· 0.0% port· 905 sh· — QoQ· Q2 2026
Rockefeller Capital Management L.P.Added
Hedge Fund
$898K· 0.6% of total· 0.0% port· 433 sh· $-296K QoQ· Q2 2026
MILLENNIUM MANAGEMENT LLCReduced
Hedge Fund
$296K· 0.2% of total· 0.0% port· 143 sh· $-506K QoQ· Q2 2026
Clearbridge Investments, LLCUnchanged
Hedge Fund
$207K· 0.1% of total· 0.0% port· 100 sh· +$0 QoQ· Q2 2026
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