wtm-20230930
000077686712/312023Q3false00007768672023-01-012023-09-3000007768672023-11-02xbrli:shares0000776867wtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMember2023-09-30iso4217:USD0000776867wtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMember2022-12-310000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMember2023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMember2022-12-310000776867us-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2023-09-300000776867us-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2022-12-310000776867us-gaap:CorporateNonSegmentMember2023-09-300000776867us-gaap:CorporateNonSegmentMember2022-12-3100007768672023-09-3000007768672022-12-31iso4217:USDxbrli:shares0000776867wtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMember2023-07-012023-09-300000776867wtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMember2022-07-012022-09-300000776867wtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMember2023-01-012023-09-300000776867wtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMember2022-01-012022-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMember2023-07-012023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMember2022-07-012022-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMember2023-01-012023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMember2022-01-012022-09-300000776867us-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2023-07-012023-09-300000776867us-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2022-07-012022-09-300000776867us-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2023-01-012023-09-300000776867us-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2022-01-012022-09-300000776867us-gaap:CorporateNonSegmentMember2023-07-012023-09-300000776867us-gaap:CorporateNonSegmentMember2022-07-012022-09-300000776867us-gaap:CorporateNonSegmentMember2023-01-012023-09-300000776867us-gaap:CorporateNonSegmentMember2022-01-012022-09-300000776867us-gaap:CorporateNonSegmentMemberwtm:InvestmentsExcludingMediaAlphaMember2023-07-012023-09-300000776867us-gaap:CorporateNonSegmentMemberwtm:InvestmentsExcludingMediaAlphaMember2022-07-012022-09-300000776867us-gaap:CorporateNonSegmentMemberwtm:InvestmentsExcludingMediaAlphaMember2023-01-012023-09-300000776867us-gaap:CorporateNonSegmentMemberwtm:InvestmentsExcludingMediaAlphaMember2022-01-012022-09-300000776867us-gaap:CorporateNonSegmentMemberwtm:MediaAlphaMember2023-07-012023-09-300000776867us-gaap:CorporateNonSegmentMemberwtm:MediaAlphaMember2022-07-012022-09-300000776867us-gaap:CorporateNonSegmentMemberwtm:MediaAlphaMember2023-01-012023-09-300000776867us-gaap:CorporateNonSegmentMemberwtm:MediaAlphaMember2022-01-012022-09-3000007768672023-07-012023-09-3000007768672022-07-012022-09-3000007768672022-01-012022-09-300000776867us-gaap:CommonStockIncludingAdditionalPaidInCapitalMember2023-06-300000776867us-gaap:RetainedEarningsMember2023-06-300000776867us-gaap:AccumulatedOtherComprehensiveIncomeMember2023-06-300000776867us-gaap:ParentMember2023-06-300000776867us-gaap:NoncontrollingInterestMember2023-06-300000776867wtm:TotalEquityIncludingNoncontrollingInterestMember2023-06-300000776867us-gaap:RetainedEarningsMember2023-07-012023-09-300000776867us-gaap:ParentMember2023-07-012023-09-300000776867us-gaap:NoncontrollingInterestMember2023-07-012023-09-300000776867wtm:TotalEquityIncludingNoncontrollingInterestMember2023-07-012023-09-300000776867us-gaap:AccumulatedOtherComprehensiveIncomeMember2023-07-012023-09-300000776867us-gaap:CommonStockIncludingAdditionalPaidInCapitalMember2023-07-012023-09-300000776867us-gaap:CommonStockIncludingAdditionalPaidInCapitalMember2023-09-300000776867us-gaap:RetainedEarningsMember2023-09-300000776867us-gaap:AccumulatedOtherComprehensiveIncomeMember2023-09-300000776867us-gaap:ParentMember2023-09-300000776867us-gaap:NoncontrollingInterestMember2023-09-300000776867wtm:TotalEquityIncludingNoncontrollingInterestMember2023-09-300000776867us-gaap:CommonStockIncludingAdditionalPaidInCapitalMember2022-06-300000776867us-gaap:RetainedEarningsMember2022-06-300000776867us-gaap:AccumulatedOtherComprehensiveIncomeMember2022-06-300000776867us-gaap:ParentMember2022-06-300000776867us-gaap:NoncontrollingInterestMember2022-06-300000776867wtm:TotalEquityIncludingNoncontrollingInterestMember2022-06-300000776867us-gaap:RetainedEarningsMember2022-07-012022-09-300000776867us-gaap:ParentMember2022-07-012022-09-300000776867us-gaap:NoncontrollingInterestMember2022-07-012022-09-300000776867wtm:TotalEquityIncludingNoncontrollingInterestMember2022-07-012022-09-300000776867us-gaap:AccumulatedOtherComprehensiveIncomeMember2022-07-012022-09-300000776867us-gaap:CommonStockIncludingAdditionalPaidInCapitalMember2022-07-012022-09-300000776867us-gaap:CommonStockIncludingAdditionalPaidInCapitalMember2022-09-300000776867us-gaap:RetainedEarningsMember2022-09-300000776867us-gaap:AccumulatedOtherComprehensiveIncomeMember2022-09-300000776867us-gaap:ParentMember2022-09-300000776867us-gaap:NoncontrollingInterestMember2022-09-300000776867wtm:TotalEquityIncludingNoncontrollingInterestMember2022-09-300000776867us-gaap:CommonStockIncludingAdditionalPaidInCapitalMember2022-12-310000776867us-gaap:RetainedEarningsMember2022-12-310000776867us-gaap:AccumulatedOtherComprehensiveIncomeMember2022-12-310000776867us-gaap:ParentMember2022-12-310000776867us-gaap:NoncontrollingInterestMember2022-12-310000776867wtm:TotalEquityIncludingNoncontrollingInterestMember2022-12-310000776867us-gaap:RetainedEarningsMember2023-01-012023-09-300000776867us-gaap:ParentMember2023-01-012023-09-300000776867us-gaap:NoncontrollingInterestMember2023-01-012023-09-300000776867wtm:TotalEquityIncludingNoncontrollingInterestMember2023-01-012023-09-300000776867us-gaap:AccumulatedOtherComprehensiveIncomeMember2023-01-012023-09-300000776867us-gaap:CommonStockIncludingAdditionalPaidInCapitalMember2023-01-012023-09-300000776867us-gaap:CommonStockIncludingAdditionalPaidInCapitalMember2021-12-310000776867us-gaap:RetainedEarningsMember2021-12-310000776867us-gaap:AccumulatedOtherComprehensiveIncomeMember2021-12-310000776867us-gaap:ParentMember2021-12-310000776867us-gaap:NoncontrollingInterestMember2021-12-310000776867wtm:TotalEquityIncludingNoncontrollingInterestMember2021-12-310000776867us-gaap:RetainedEarningsMember2022-01-012022-09-300000776867us-gaap:ParentMember2022-01-012022-09-300000776867us-gaap:NoncontrollingInterestMember2022-01-012022-09-300000776867wtm:TotalEquityIncludingNoncontrollingInterestMember2022-01-012022-09-300000776867us-gaap:AccumulatedOtherComprehensiveIncomeMember2022-01-012022-09-300000776867us-gaap:CommonStockIncludingAdditionalPaidInCapitalMember2022-01-012022-09-300000776867wtm:InvestmentsExcludingMediaAlphaMember2023-01-012023-09-300000776867wtm:InvestmentsExcludingMediaAlphaMember2022-01-012022-09-300000776867wtm:MediaAlphaMember2023-01-012023-09-300000776867wtm:MediaAlphaMember2022-01-012022-09-3000007768672021-12-310000776867wtm:NSMInsuranceGroupMemberus-gaap:DiscontinuedOperationsDisposedOfBySaleMember2022-12-310000776867wtm:NSMInsuranceGroupMemberus-gaap:DiscontinuedOperationsDisposedOfBySaleMember2021-12-3100007768672022-09-300000776867wtm:NSMInsuranceGroupMemberus-gaap:DiscontinuedOperationsDisposedOfBySaleMember2023-09-300000776867wtm:NSMInsuranceGroupMemberus-gaap:DiscontinuedOperationsDisposedOfBySaleMember2022-09-30wtm:segment0000776867wtm:SubsidiaryHGGlobalMembersrt:MaximumMember2023-09-30xbrli:pure0000776867wtm:SubsidiaryHGGlobalMember2023-01-012023-09-300000776867wtm:SubsidiaryHGGlobalMemberus-gaap:PreferredStockMember2022-12-310000776867wtm:SubsidiaryHGGlobalMemberus-gaap:PreferredStockMember2023-09-300000776867wtm:SubsidiaryHGGlobalMemberus-gaap:CommonStockMember2022-12-310000776867wtm:SubsidiaryArkInsuranceHoldingsLimitedMember2022-12-310000776867wtm:SubsidiaryArkInsuranceHoldingsLimitedMember2023-09-300000776867us-gaap:RedeemablePreferredStockMemberwtm:OutriggerReLtdMember2022-12-20wtm:account0000776867us-gaap:PreferredStockMemberwtm:SubsidiaryWMOutriggerReMember2022-12-310000776867us-gaap:PreferredStockMemberwtm:SubsidiaryWMOutriggerReMember2023-09-300000776867wtm:SubsidiaryKuduInvestmentManagementLLCMember2022-12-310000776867wtm:SubsidiaryKuduInvestmentManagementLLCMember2023-09-300000776867wtm:NSMInsuranceGroupMemberus-gaap:DiscontinuedOperationsDisposedOfBySaleMember2022-08-010000776867wtm:NSMInsuranceGroupMemberus-gaap:DiscontinuedOperationsDisposedOfBySaleMember2022-08-012022-08-010000776867us-gaap:RedeemablePreferredStockMemberwtm:OutriggerReLtdMember2022-12-202022-12-200000776867wtm:OutriggerReMember2022-10-012022-12-310000776867wtm:SubsidiaryKuduInvestmentManagementLLCMember2022-05-262022-05-260000776867wtm:MassachusettsMutualLifeInsuranceCompanyMemberwtm:SubsidiaryKuduInvestmentManagementLLCMember2022-05-262022-05-260000776867wtm:SubsidiaryKuduInvestmentManagementLLCMemberwtm:WhiteMountainsMember2022-05-262022-05-260000776867wtm:KuduInvestmentManagementLLCMemberwtm:SubsidiaryKuduInvestmentManagementLLCMember2022-05-262022-05-260000776867wtm:SubsidiaryKuduInvestmentManagementLLCMemberwtm:KuduParticipationContractsMember2021-12-31wtm:portfolioCompany0000776867wtm:SubsidiaryKuduInvestmentManagementLLCMember2022-05-250000776867wtm:SubsidiaryKuduInvestmentManagementLLCMember2022-05-260000776867us-gaap:FixedMaturitiesMember2023-07-012023-09-300000776867us-gaap:FixedMaturitiesMember2022-07-012022-09-300000776867us-gaap:FixedMaturitiesMember2023-01-012023-09-300000776867us-gaap:FixedMaturitiesMember2022-01-012022-09-300000776867us-gaap:ShortTermInvestmentsMember2023-07-012023-09-300000776867us-gaap:ShortTermInvestmentsMember2022-07-012022-09-300000776867us-gaap:ShortTermInvestmentsMember2023-01-012023-09-300000776867us-gaap:ShortTermInvestmentsMember2022-01-012022-09-300000776867us-gaap:CommonStockMember2023-07-012023-09-300000776867us-gaap:CommonStockMember2022-07-012022-09-300000776867us-gaap:CommonStockMember2023-01-012023-09-300000776867us-gaap:CommonStockMember2022-01-012022-09-300000776867us-gaap:OtherLongTermInvestmentsMember2023-07-012023-09-300000776867us-gaap:OtherLongTermInvestmentsMember2022-07-012022-09-300000776867us-gaap:OtherLongTermInvestmentsMember2023-01-012023-09-300000776867us-gaap:OtherLongTermInvestmentsMember2022-01-012022-09-300000776867wtm:TPCProvidersInvestmentsMember2023-07-012023-09-300000776867wtm:TPCProvidersInvestmentsMember2022-07-012022-09-300000776867wtm:TPCProvidersInvestmentsMember2023-01-012023-09-300000776867wtm:TPCProvidersInvestmentsMember2022-01-012022-09-300000776867us-gaap:FixedMaturitiesMember2023-07-012023-09-300000776867us-gaap:FixedMaturitiesMember2022-07-012022-09-300000776867us-gaap:FixedMaturitiesMember2023-01-012023-09-300000776867us-gaap:FixedMaturitiesMember2022-01-012022-09-300000776867wtm:OtherShortTermInvestmentsMember2023-07-012023-09-300000776867wtm:OtherShortTermInvestmentsMember2022-07-012022-09-300000776867wtm:OtherShortTermInvestmentsMember2023-01-012023-09-300000776867wtm:OtherShortTermInvestmentsMember2022-01-012022-09-300000776867us-gaap:CommonStockMember2023-07-012023-09-300000776867us-gaap:CommonStockMember2022-07-012022-09-300000776867us-gaap:CommonStockMember2023-01-012023-09-300000776867us-gaap:CommonStockMember2022-01-012022-09-300000776867us-gaap:OtherLongTermInvestmentsMember2023-07-012023-09-300000776867us-gaap:OtherLongTermInvestmentsMember2022-07-012022-09-300000776867us-gaap:OtherLongTermInvestmentsMember2023-01-012023-09-300000776867us-gaap:OtherLongTermInvestmentsMember2022-01-012022-09-300000776867wtm:TotalInvestmentsBeforeTPCProvidersInvestmentsMember2023-07-012023-09-300000776867wtm:TotalInvestmentsBeforeTPCProvidersInvestmentsMember2022-07-012022-09-300000776867wtm:TotalInvestmentsBeforeTPCProvidersInvestmentsMember2023-01-012023-09-300000776867wtm:TotalInvestmentsBeforeTPCProvidersInvestmentsMember2022-01-012022-09-300000776867us-gaap:EquityMethodInvestmentsMemberwtm:MediaAlphaMember2023-07-012023-09-300000776867us-gaap:EquityMethodInvestmentsMemberwtm:MediaAlphaMember2022-07-012022-09-300000776867us-gaap:EquityMethodInvestmentsMemberwtm:MediaAlphaMember2023-01-012023-09-300000776867us-gaap:EquityMethodInvestmentsMemberwtm:MediaAlphaMember2022-01-012022-09-300000776867wtm:FixedMaturitiesAndOtherShortTermInvestmentsMember2023-07-012023-09-300000776867wtm:FixedMaturitiesAndOtherShortTermInvestmentsMember2022-07-012022-09-300000776867wtm:FixedMaturitiesAndOtherShortTermInvestmentsMember2023-01-012023-09-300000776867wtm:FixedMaturitiesAndOtherShortTermInvestmentsMember2022-01-012022-09-300000776867wtm:CommonStockAndEquityMethodInvestmentsMember2023-07-012023-09-300000776867wtm:CommonStockAndEquityMethodInvestmentsMember2022-07-012022-09-300000776867wtm:CommonStockAndEquityMethodInvestmentsMember2023-01-012023-09-300000776867wtm:CommonStockAndEquityMethodInvestmentsMember2022-01-012022-09-300000776867wtm:TotalInvestmentsAfterTPCProvidersInvestmentsMember2023-07-012023-09-300000776867wtm:TotalInvestmentsAfterTPCProvidersInvestmentsMember2022-07-012022-09-300000776867wtm:TotalInvestmentsAfterTPCProvidersInvestmentsMember2023-01-012023-09-300000776867wtm:TotalInvestmentsAfterTPCProvidersInvestmentsMember2022-01-012022-09-300000776867us-gaap:OtherLongTermInvestmentsMemberus-gaap:FairValueInputsLevel3Member2023-07-012023-09-300000776867us-gaap:OtherLongTermInvestmentsMemberus-gaap:FairValueInputsLevel3Member2022-07-012022-09-300000776867us-gaap:OtherLongTermInvestmentsMemberus-gaap:FairValueInputsLevel3Member2023-01-012023-09-300000776867us-gaap:OtherLongTermInvestmentsMemberus-gaap:FairValueInputsLevel3Member2022-01-012022-09-300000776867us-gaap:USTreasuryAndGovernmentMember2023-09-300000776867us-gaap:USTreasuryAndGovernmentMember2023-01-012023-09-300000776867us-gaap:CorporateDebtSecuritiesMember2023-09-300000776867us-gaap:CorporateDebtSecuritiesMember2023-01-012023-09-300000776867us-gaap:MunicipalBondsMember2023-09-300000776867us-gaap:MunicipalBondsMember2023-01-012023-09-300000776867us-gaap:AssetBackedSecuritiesMember2023-09-300000776867us-gaap:AssetBackedSecuritiesMember2023-01-012023-09-300000776867us-gaap:CollateralizedLoanObligationsMember2023-09-300000776867us-gaap:CollateralizedLoanObligationsMember2023-01-012023-09-300000776867us-gaap:FixedMaturitiesMember2023-09-300000776867us-gaap:USTreasuryAndGovernmentMember2022-12-310000776867us-gaap:USTreasuryAndGovernmentMember2022-01-012022-12-310000776867us-gaap:CorporateDebtSecuritiesMember2022-12-310000776867us-gaap:CorporateDebtSecuritiesMember2022-01-012022-12-310000776867us-gaap:MunicipalBondsMember2022-12-310000776867us-gaap:MunicipalBondsMember2022-01-012022-12-310000776867us-gaap:AssetBackedSecuritiesMember2022-12-310000776867us-gaap:AssetBackedSecuritiesMember2022-01-012022-12-310000776867us-gaap:CollateralizedLoanObligationsMember2022-12-310000776867us-gaap:CollateralizedLoanObligationsMember2022-01-012022-12-310000776867us-gaap:FixedMaturitiesMember2022-12-310000776867us-gaap:FixedMaturitiesMember2022-01-012022-12-310000776867wtm:FixedMaturitiesExcludingAssetBackedSecuritiesAndCollateralizedLoanObligationsMember2023-09-300000776867wtm:AssetBackedSecuritiesAndCollateralizedLoanObligationsMember2023-09-300000776867wtm:MediaAlphaMember2023-09-3000007768672022-01-012022-12-310000776867wtm:MediaAlphaMember2022-12-310000776867wtm:MediaAlphaMember2022-01-012022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:USTreasuryAndGovernmentMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:USTreasuryAndGovernmentMemberus-gaap:FairValueInputsLevel1Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:USTreasuryAndGovernmentMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:USTreasuryAndGovernmentMemberus-gaap:FairValueInputsLevel3Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FinancialServicesSectorMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel1Memberus-gaap:FinancialServicesSectorMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Memberus-gaap:FinancialServicesSectorMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FinancialServicesSectorMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:ConsumerSectorMemberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:ConsumerSectorMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel1Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:ConsumerSectorMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberus-gaap:ConsumerSectorMemberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:HealthcareSectorMemberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:HealthcareSectorMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel1Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:HealthcareSectorMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:HealthcareSectorMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867us-gaap:CommercialAndIndustrialSectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867us-gaap:CommercialAndIndustrialSectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel1Member2023-09-300000776867us-gaap:CommercialAndIndustrialSectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:CommercialAndIndustrialSectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867us-gaap:TechnologySectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867us-gaap:TechnologySectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel1Member2023-09-300000776867us-gaap:TechnologySectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:TechnologySectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:UtilitiesSectorMemberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:UtilitiesSectorMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel1Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:UtilitiesSectorMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberwtm:UtilitiesSectorMemberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:CommunicationsSectorMemberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:CommunicationsSectorMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel1Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:CommunicationsSectorMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:CommunicationsSectorMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:EnergySectorMemberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:EnergySectorMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel1Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:EnergySectorMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:EnergySectorMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867wtm:MaterialsSectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867wtm:MaterialsSectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel1Member2023-09-300000776867wtm:MaterialsSectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867wtm:MaterialsSectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel1Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867us-gaap:MunicipalBondsMemberus-gaap:FairValueMeasurementsRecurringMember2023-09-300000776867us-gaap:MunicipalBondsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel1Member2023-09-300000776867us-gaap:MunicipalBondsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:MunicipalBondsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:AssetBackedSecuritiesMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:AssetBackedSecuritiesMemberus-gaap:FairValueInputsLevel1Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:AssetBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberus-gaap:AssetBackedSecuritiesMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CollateralizedLoanObligationsMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CollateralizedLoanObligationsMemberus-gaap:FairValueInputsLevel1Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CollateralizedLoanObligationsMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CollateralizedLoanObligationsMemberus-gaap:FairValueInputsLevel3Member2023-09-300000776867us-gaap:FixedMaturitiesMemberus-gaap:FairValueMeasurementsRecurringMember2023-09-300000776867us-gaap:FixedMaturitiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel1Member2023-09-300000776867us-gaap:FixedMaturitiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FixedMaturitiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:OtherShortTermInvestmentsMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:OtherShortTermInvestmentsMemberus-gaap:FairValueInputsLevel1Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:OtherShortTermInvestmentsMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberwtm:OtherShortTermInvestmentsMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:CommonStockExchangeTradedFundsMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel1Memberwtm:CommonStockExchangeTradedFundsMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:CommonStockExchangeTradedFundsMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberwtm:CommonStockExchangeTradedFundsMember2023-09-300000776867wtm:CommonStockOtherMemberus-gaap:FairValueMeasurementsRecurringMember2023-09-300000776867wtm:CommonStockOtherMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel1Member2023-09-300000776867wtm:CommonStockOtherMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867wtm:CommonStockOtherMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Member2023-09-300000776867us-gaap:CommonStockMemberus-gaap:FairValueMeasurementsRecurringMember2023-09-300000776867us-gaap:CommonStockMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel1Member2023-09-300000776867us-gaap:CommonStockMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:CommonStockMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:MediaAlphaMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:MediaAlphaMemberus-gaap:FairValueInputsLevel1Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:MediaAlphaMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberwtm:MediaAlphaMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:OtherLongTermInvestmentsMemberus-gaap:FairValueInputsLevel12And3Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:OtherLongTermInvestmentsMemberus-gaap:FairValueInputsLevel1Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:OtherLongTermInvestmentsMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:OtherLongTermInvestmentsMemberus-gaap:FairValueInputsLevel3Member2023-09-300000776867us-gaap:FairValueMeasuredAtNetAssetValuePerShareMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:OtherLongTermInvestmentsMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:TotalOtherLongTermInvestmentsMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel1Memberwtm:TotalOtherLongTermInvestmentsMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel2Memberwtm:TotalOtherLongTermInvestmentsMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberwtm:TotalOtherLongTermInvestmentsMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMember2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel1Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Member2023-09-300000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:USTreasuryAndGovernmentMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:USTreasuryAndGovernmentMemberus-gaap:FairValueInputsLevel1Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:USTreasuryAndGovernmentMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:USTreasuryAndGovernmentMemberus-gaap:FairValueInputsLevel3Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FinancialServicesSectorMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel1Memberus-gaap:FinancialServicesSectorMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Memberus-gaap:FinancialServicesSectorMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FinancialServicesSectorMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:ConsumerSectorMemberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:ConsumerSectorMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel1Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:ConsumerSectorMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberus-gaap:ConsumerSectorMemberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:HealthcareSectorMemberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:HealthcareSectorMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel1Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:HealthcareSectorMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:HealthcareSectorMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867us-gaap:CommercialAndIndustrialSectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867us-gaap:CommercialAndIndustrialSectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel1Member2022-12-310000776867us-gaap:CommercialAndIndustrialSectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:CommercialAndIndustrialSectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867us-gaap:TechnologySectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867us-gaap:TechnologySectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel1Member2022-12-310000776867us-gaap:TechnologySectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:TechnologySectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:UtilitiesSectorMemberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:UtilitiesSectorMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel1Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:UtilitiesSectorMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberwtm:UtilitiesSectorMemberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:CommunicationsSectorMemberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:CommunicationsSectorMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel1Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:CommunicationsSectorMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:CommunicationsSectorMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:EnergySectorMemberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:EnergySectorMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel1Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:EnergySectorMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:EnergySectorMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867wtm:MaterialsSectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867wtm:MaterialsSectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel1Member2022-12-310000776867wtm:MaterialsSectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867wtm:MaterialsSectorMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel1Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867us-gaap:MunicipalBondsMemberus-gaap:FairValueMeasurementsRecurringMember2022-12-310000776867us-gaap:MunicipalBondsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel1Member2022-12-310000776867us-gaap:MunicipalBondsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:MunicipalBondsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:AssetBackedSecuritiesMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:AssetBackedSecuritiesMemberus-gaap:FairValueInputsLevel1Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:AssetBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberus-gaap:AssetBackedSecuritiesMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CollateralizedLoanObligationsMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CollateralizedLoanObligationsMemberus-gaap:FairValueInputsLevel1Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CollateralizedLoanObligationsMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CollateralizedLoanObligationsMemberus-gaap:FairValueInputsLevel3Member2022-12-310000776867us-gaap:FixedMaturitiesMemberus-gaap:FairValueMeasurementsRecurringMember2022-12-310000776867us-gaap:FixedMaturitiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel1Member2022-12-310000776867us-gaap:FixedMaturitiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FixedMaturitiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:OtherShortTermInvestmentsMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:OtherShortTermInvestmentsMemberus-gaap:FairValueInputsLevel1Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:OtherShortTermInvestmentsMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberwtm:OtherShortTermInvestmentsMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:CommonStockExchangeTradedFundsMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel1Memberwtm:CommonStockExchangeTradedFundsMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:CommonStockExchangeTradedFundsMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberwtm:CommonStockExchangeTradedFundsMember2022-12-310000776867wtm:CommonStockOtherMemberus-gaap:FairValueMeasurementsRecurringMember2022-12-310000776867wtm:CommonStockOtherMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel1Member2022-12-310000776867wtm:CommonStockOtherMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867wtm:CommonStockOtherMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Member2022-12-310000776867us-gaap:CommonStockMemberus-gaap:FairValueMeasurementsRecurringMember2022-12-310000776867us-gaap:CommonStockMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel1Member2022-12-310000776867us-gaap:CommonStockMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:CommonStockMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:MediaAlphaMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:MediaAlphaMemberus-gaap:FairValueInputsLevel1Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:MediaAlphaMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberwtm:MediaAlphaMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:OtherLongTermInvestmentsMemberus-gaap:FairValueInputsLevel12And3Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:OtherLongTermInvestmentsMemberus-gaap:FairValueInputsLevel1Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:OtherLongTermInvestmentsMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:OtherLongTermInvestmentsMemberus-gaap:FairValueInputsLevel3Member2022-12-310000776867us-gaap:FairValueMeasuredAtNetAssetValuePerShareMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:OtherLongTermInvestmentsMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberwtm:TotalOtherLongTermInvestmentsMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel1Memberwtm:TotalOtherLongTermInvestmentsMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel2Memberwtm:TotalOtherLongTermInvestmentsMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Memberwtm:TotalOtherLongTermInvestmentsMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMember2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel1Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FairValueMeasurementsRecurringMemberus-gaap:FairValueInputsLevel3Member2022-12-310000776867wtm:HGGlobalSeniorNotesMemberus-gaap:SeniorNotesMember2023-09-300000776867wtm:HGGlobalSeniorNotesMemberus-gaap:SeniorNotesMember2022-12-310000776867wtm:TrustDepositsMember2023-09-300000776867wtm:TrustDepositsMember2022-12-310000776867wtm:LloydsBankMember2023-09-300000776867wtm:LloydsBankMember2022-12-310000776867wtm:AdditionalInvestmentsInsuranceRegulatorsAndReinsuranceCounterpartiesMemberus-gaap:AssetPledgedAsCollateralMember2023-09-300000776867wtm:AdditionalInvestmentsInsuranceRegulatorsAndReinsuranceCounterpartiesMemberus-gaap:AssetPledgedAsCollateralMember2022-12-310000776867us-gaap:AssetPledgedAsCollateralMember2023-09-300000776867us-gaap:AssetPledgedAsCollateralMember2022-12-310000776867wtm:OutriggerReMember2023-09-300000776867wtm:OutriggerReMember2022-12-310000776867wtm:KuduCreditFacilityMemberus-gaap:SecuredDebtMember2023-09-300000776867wtm:KuduCreditFacilityMemberus-gaap:SecuredDebtMember2022-12-310000776867us-gaap:CorporateDebtSecuritiesMembersrt:StandardPoorsAAARatingMember2023-09-300000776867us-gaap:CorporateDebtSecuritiesMembersrt:StandardPoorsAAARatingMember2022-12-310000776867srt:StandardPoorsAARatingMemberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867srt:StandardPoorsAARatingMemberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867srt:StandardPoorsARatingMemberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867srt:StandardPoorsARatingMemberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867srt:StandardPoorsBBBRatingMemberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867srt:StandardPoorsBBBRatingMemberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867wtm:StandardPoorsOtherMemberus-gaap:CorporateDebtSecuritiesMember2023-09-300000776867wtm:StandardPoorsOtherMemberus-gaap:CorporateDebtSecuritiesMember2022-12-310000776867us-gaap:FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMemberus-gaap:MortgageBackedSecuritiesMember2023-09-300000776867us-gaap:FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMemberus-gaap:MortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMemberus-gaap:FairValueInputsLevel3Memberus-gaap:MortgageBackedSecuritiesMember2023-09-300000776867us-gaap:FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMemberus-gaap:MortgageBackedSecuritiesMember2022-12-310000776867us-gaap:FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMemberus-gaap:MortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMemberus-gaap:FairValueInputsLevel3Memberus-gaap:MortgageBackedSecuritiesMember2022-12-310000776867us-gaap:FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMemberus-gaap:MortgageBackedSecuritiesMember2023-09-300000776867us-gaap:FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMemberus-gaap:MortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMemberus-gaap:FairValueInputsLevel3Memberus-gaap:MortgageBackedSecuritiesMember2023-09-300000776867us-gaap:FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMemberus-gaap:MortgageBackedSecuritiesMember2022-12-310000776867us-gaap:FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMemberus-gaap:MortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMemberus-gaap:FairValueInputsLevel3Memberus-gaap:MortgageBackedSecuritiesMember2022-12-310000776867us-gaap:GovernmentNationalMortgageAssociationCertificatesAndObligationsGNMAMemberus-gaap:MortgageBackedSecuritiesMember2023-09-300000776867us-gaap:GovernmentNationalMortgageAssociationCertificatesAndObligationsGNMAMemberus-gaap:MortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:GovernmentNationalMortgageAssociationCertificatesAndObligationsGNMAMemberus-gaap:FairValueInputsLevel3Memberus-gaap:MortgageBackedSecuritiesMember2023-09-300000776867us-gaap:GovernmentNationalMortgageAssociationCertificatesAndObligationsGNMAMemberus-gaap:MortgageBackedSecuritiesMember2022-12-310000776867us-gaap:GovernmentNationalMortgageAssociationCertificatesAndObligationsGNMAMemberus-gaap:MortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:GovernmentNationalMortgageAssociationCertificatesAndObligationsGNMAMemberus-gaap:FairValueInputsLevel3Memberus-gaap:MortgageBackedSecuritiesMember2022-12-310000776867us-gaap:MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMemberus-gaap:MortgageBackedSecuritiesMember2023-09-300000776867us-gaap:MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMemberus-gaap:MortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:MortgageBackedSecuritiesMember2023-09-300000776867us-gaap:MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMemberus-gaap:MortgageBackedSecuritiesMember2022-12-310000776867us-gaap:MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMemberus-gaap:MortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:MortgageBackedSecuritiesMember2022-12-310000776867us-gaap:MortgageBackedSecuritiesMemberus-gaap:ResidentialMortgageBackedSecuritiesMember2023-09-300000776867us-gaap:MortgageBackedSecuritiesMemberus-gaap:ResidentialMortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FairValueInputsLevel3Memberus-gaap:MortgageBackedSecuritiesMemberus-gaap:ResidentialMortgageBackedSecuritiesMember2023-09-300000776867us-gaap:MortgageBackedSecuritiesMemberus-gaap:ResidentialMortgageBackedSecuritiesMember2022-12-310000776867us-gaap:MortgageBackedSecuritiesMemberus-gaap:ResidentialMortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FairValueInputsLevel3Memberus-gaap:MortgageBackedSecuritiesMemberus-gaap:ResidentialMortgageBackedSecuritiesMember2022-12-310000776867us-gaap:MortgageBackedSecuritiesIssuedByPrivateEnterprisesMemberus-gaap:MortgageBackedSecuritiesMember2023-09-300000776867us-gaap:MortgageBackedSecuritiesIssuedByPrivateEnterprisesMemberus-gaap:MortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FairValueInputsLevel3Memberus-gaap:MortgageBackedSecuritiesIssuedByPrivateEnterprisesMemberus-gaap:MortgageBackedSecuritiesMember2023-09-300000776867us-gaap:MortgageBackedSecuritiesIssuedByPrivateEnterprisesMemberus-gaap:MortgageBackedSecuritiesMember2022-12-310000776867us-gaap:MortgageBackedSecuritiesIssuedByPrivateEnterprisesMemberus-gaap:MortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FairValueInputsLevel3Memberus-gaap:MortgageBackedSecuritiesIssuedByPrivateEnterprisesMemberus-gaap:MortgageBackedSecuritiesMember2022-12-310000776867us-gaap:MortgageBackedSecuritiesMember2023-09-300000776867us-gaap:MortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FairValueInputsLevel3Memberus-gaap:MortgageBackedSecuritiesMember2023-09-300000776867us-gaap:MortgageBackedSecuritiesMember2022-12-310000776867us-gaap:MortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FairValueInputsLevel3Memberus-gaap:MortgageBackedSecuritiesMember2022-12-310000776867us-gaap:CollateralizedCreditCardSecuritiesMemberus-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMember2023-09-300000776867us-gaap:CollateralizedCreditCardSecuritiesMemberus-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:CollateralizedCreditCardSecuritiesMemberus-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMemberus-gaap:FairValueInputsLevel3Member2023-09-300000776867us-gaap:CollateralizedCreditCardSecuritiesMemberus-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMember2022-12-310000776867us-gaap:CollateralizedCreditCardSecuritiesMemberus-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:CollateralizedCreditCardSecuritiesMemberus-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMemberus-gaap:FairValueInputsLevel3Member2022-12-310000776867us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMemberus-gaap:CollateralizedAutoLoansMember2023-09-300000776867us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMemberus-gaap:CollateralizedAutoLoansMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMemberus-gaap:CollateralizedAutoLoansMemberus-gaap:FairValueInputsLevel3Member2023-09-300000776867us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMemberus-gaap:CollateralizedAutoLoansMember2022-12-310000776867us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMemberus-gaap:CollateralizedAutoLoansMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMemberus-gaap:CollateralizedAutoLoansMemberus-gaap:FairValueInputsLevel3Member2022-12-310000776867us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMemberwtm:OtherAssetBackedSecuritiesMember2023-09-300000776867us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMemberwtm:OtherAssetBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMemberwtm:OtherAssetBackedSecuritiesMemberus-gaap:FairValueInputsLevel3Member2023-09-300000776867us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMemberwtm:OtherAssetBackedSecuritiesMember2022-12-310000776867us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMemberwtm:OtherAssetBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMemberwtm:OtherAssetBackedSecuritiesMemberus-gaap:FairValueInputsLevel3Member2022-12-310000776867us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMember2023-09-300000776867us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMemberus-gaap:FairValueInputsLevel3Member2023-09-300000776867us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMember2022-12-310000776867us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivablesMemberus-gaap:FairValueInputsLevel3Member2022-12-310000776867us-gaap:AssetBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FairValueInputsLevel3Memberus-gaap:AssetBackedSecuritiesMember2023-09-300000776867us-gaap:AssetBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FairValueInputsLevel3Memberus-gaap:AssetBackedSecuritiesMember2022-12-310000776867us-gaap:CollateralizedLoanObligationsMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:CollateralizedLoanObligationsMemberus-gaap:FairValueInputsLevel3Member2023-09-300000776867us-gaap:CollateralizedLoanObligationsMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:CollateralizedLoanObligationsMemberus-gaap:FairValueInputsLevel3Member2022-12-310000776867wtm:MortgageAndAssetBackedSecuritiesAndCollateralizedLoanObligationsMember2023-09-300000776867wtm:MortgageAndAssetBackedSecuritiesAndCollateralizedLoanObligationsMemberus-gaap:FairValueInputsLevel2Member2023-09-300000776867us-gaap:FairValueInputsLevel3Memberwtm:MortgageAndAssetBackedSecuritiesAndCollateralizedLoanObligationsMember2023-09-300000776867wtm:MortgageAndAssetBackedSecuritiesAndCollateralizedLoanObligationsMember2022-12-310000776867wtm:MortgageAndAssetBackedSecuritiesAndCollateralizedLoanObligationsMemberus-gaap:FairValueInputsLevel2Member2022-12-310000776867us-gaap:FairValueInputsLevel3Memberwtm:MortgageAndAssetBackedSecuritiesAndCollateralizedLoanObligationsMember2022-12-310000776867wtm:MediaAlphaMember2023-04-012023-06-300000776867wtm:MediaAlphaMemberus-gaap:IPOMember2023-01-012023-09-300000776867wtm:KuduInvestmentManagementLLCMemberwtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMemberwtm:KuduParticipationContractsMember2023-09-300000776867wtm:KuduInvestmentManagementLLCMemberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMemberwtm:KuduParticipationContractsMember2023-09-300000776867wtm:KuduInvestmentManagementLLCMemberus-gaap:CorporateNonSegmentMemberwtm:KuduParticipationContractsMember2023-09-300000776867wtm:KuduInvestmentManagementLLCMemberwtm:KuduParticipationContractsMember2023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMemberwtm:DavidShieldPassportCardMember2023-09-300000776867us-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMemberwtm:DavidShieldPassportCardMember2023-09-300000776867us-gaap:CorporateNonSegmentMemberwtm:DavidShieldPassportCardMember2023-09-300000776867wtm:DavidShieldPassportCardMember2023-09-300000776867wtm:ElementumHoldingsL.P.Memberwtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMember2023-09-300000776867wtm:ElementumHoldingsL.P.Memberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2023-09-300000776867wtm:ElementumHoldingsL.P.Memberus-gaap:CorporateNonSegmentMember2023-09-300000776867wtm:ElementumHoldingsL.P.Member2023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMemberwtm:MandatorilyRedeemablePreferredSecuritiesMember2023-09-300000776867us-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMemberwtm:MandatorilyRedeemablePreferredSecuritiesMember2023-09-300000776867us-gaap:CorporateNonSegmentMemberwtm:MandatorilyRedeemablePreferredSecuritiesMember2023-09-300000776867wtm:MandatorilyRedeemablePreferredSecuritiesMember2023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:OtherUnconsolidatedPrivateEquityInvestmentsMemberus-gaap:OperatingSegmentsMember2023-09-300000776867wtm:OtherUnconsolidatedPrivateEquityInvestmentsMemberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2023-09-300000776867us-gaap:CorporateNonSegmentMemberwtm:OtherUnconsolidatedPrivateEquityInvestmentsMember2023-09-300000776867wtm:OtherUnconsolidatedPrivateEquityInvestmentsMember2023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:InvestmentsExcludingMediaAlphaMemberwtm:TotalUnconsolidatedEntitiesMemberus-gaap:OperatingSegmentsMember2023-09-300000776867wtm:InvestmentsExcludingMediaAlphaMemberwtm:TotalUnconsolidatedEntitiesMemberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2023-09-300000776867us-gaap:CorporateNonSegmentMemberwtm:InvestmentsExcludingMediaAlphaMemberwtm:TotalUnconsolidatedEntitiesMember2023-09-300000776867wtm:InvestmentsExcludingMediaAlphaMemberwtm:TotalUnconsolidatedEntitiesMember2023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:PrivateEquityFundsAndHedgeFundsMemberus-gaap:OperatingSegmentsMember2023-09-300000776867wtm:PrivateEquityFundsAndHedgeFundsMemberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2023-09-300000776867us-gaap:CorporateNonSegmentMemberwtm:PrivateEquityFundsAndHedgeFundsMember2023-09-300000776867wtm:PrivateEquityFundsAndHedgeFundsMember2023-09-300000776867wtm:BankLoanFundMemberwtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMember2023-09-300000776867wtm:BankLoanFundMemberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2023-09-300000776867wtm:BankLoanFundMemberus-gaap:CorporateNonSegmentMember2023-09-300000776867wtm:BankLoanFundMember2023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMemberwtm:InsuranceLinkedSecuritiesFundsMember2023-09-300000776867us-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMemberwtm:InsuranceLinkedSecuritiesFundsMember2023-09-300000776867us-gaap:CorporateNonSegmentMemberwtm:InsuranceLinkedSecuritiesFundsMember2023-09-300000776867wtm:InsuranceLinkedSecuritiesFundsMember2023-09-300000776867wtm:TrustDepositsMemberwtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMember2023-09-300000776867wtm:TrustDepositsMemberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2023-09-300000776867wtm:TrustDepositsMemberus-gaap:CorporateNonSegmentMember2023-09-300000776867wtm:TrustDepositsMember2023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:PrivateDebtInstrumentMemberus-gaap:OperatingSegmentsMember2023-09-300000776867wtm:PrivateDebtInstrumentMemberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2023-09-300000776867us-gaap:CorporateNonSegmentMemberwtm:PrivateDebtInstrumentMember2023-09-300000776867wtm:PrivateDebtInstrumentMember2023-09-300000776867wtm:OtherFundsMemberwtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMember2023-09-300000776867wtm:OtherFundsMemberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2023-09-300000776867wtm:OtherFundsMemberus-gaap:CorporateNonSegmentMember2023-09-300000776867wtm:OtherFundsMember2023-09-300000776867wtm:KuduInvestmentManagementLLCMemberwtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMemberwtm:KuduParticipationContractsMember2022-12-310000776867wtm:KuduInvestmentManagementLLCMemberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMemberwtm:KuduParticipationContractsMember2022-12-310000776867wtm:KuduInvestmentManagementLLCMemberus-gaap:CorporateNonSegmentMemberwtm:KuduParticipationContractsMember2022-12-310000776867wtm:KuduInvestmentManagementLLCMemberwtm:KuduParticipationContractsMember2022-12-310000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMemberwtm:DavidShieldPassportCardMember2022-12-310000776867us-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMemberwtm:DavidShieldPassportCardMember2022-12-310000776867us-gaap:CorporateNonSegmentMemberwtm:DavidShieldPassportCardMember2022-12-310000776867wtm:DavidShieldPassportCardMember2022-12-310000776867wtm:ElementumHoldingsL.P.Memberwtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMember2022-12-310000776867wtm:ElementumHoldingsL.P.Memberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2022-12-310000776867wtm:ElementumHoldingsL.P.Memberus-gaap:CorporateNonSegmentMember2022-12-310000776867wtm:ElementumHoldingsL.P.Member2022-12-310000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:OtherUnconsolidatedPrivateEquityInvestmentsMemberus-gaap:OperatingSegmentsMember2022-12-310000776867wtm:OtherUnconsolidatedPrivateEquityInvestmentsMemberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2022-12-310000776867us-gaap:CorporateNonSegmentMemberwtm:OtherUnconsolidatedPrivateEquityInvestmentsMember2022-12-310000776867wtm:OtherUnconsolidatedPrivateEquityInvestmentsMember2022-12-310000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:InvestmentsExcludingMediaAlphaMemberwtm:TotalUnconsolidatedEntitiesMemberus-gaap:OperatingSegmentsMember2022-12-310000776867wtm:InvestmentsExcludingMediaAlphaMemberwtm:TotalUnconsolidatedEntitiesMemberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2022-12-310000776867us-gaap:CorporateNonSegmentMemberwtm:InvestmentsExcludingMediaAlphaMemberwtm:TotalUnconsolidatedEntitiesMember2022-12-310000776867wtm:InvestmentsExcludingMediaAlphaMemberwtm:TotalUnconsolidatedEntitiesMember2022-12-310000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:PrivateEquityFundsAndHedgeFundsMemberus-gaap:OperatingSegmentsMember2022-12-310000776867wtm:PrivateEquityFundsAndHedgeFundsMemberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2022-12-310000776867us-gaap:CorporateNonSegmentMemberwtm:PrivateEquityFundsAndHedgeFundsMember2022-12-310000776867wtm:PrivateEquityFundsAndHedgeFundsMember2022-12-310000776867wtm:BankLoanFundMemberwtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMember2022-12-310000776867wtm:BankLoanFundMemberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2022-12-310000776867wtm:BankLoanFundMemberus-gaap:CorporateNonSegmentMember2022-12-310000776867wtm:BankLoanFundMember2022-12-310000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMemberwtm:InsuranceLinkedSecuritiesFundsMember2022-12-310000776867us-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMemberwtm:InsuranceLinkedSecuritiesFundsMember2022-12-310000776867us-gaap:CorporateNonSegmentMemberwtm:InsuranceLinkedSecuritiesFundsMember2022-12-310000776867wtm:InsuranceLinkedSecuritiesFundsMember2022-12-310000776867wtm:TrustDepositsMemberwtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMember2022-12-310000776867wtm:TrustDepositsMemberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2022-12-310000776867wtm:TrustDepositsMemberus-gaap:CorporateNonSegmentMember2022-12-310000776867wtm:TrustDepositsMember2022-12-310000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:PrivateDebtInstrumentMemberus-gaap:OperatingSegmentsMember2022-12-310000776867wtm:PrivateDebtInstrumentMemberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2022-12-310000776867us-gaap:CorporateNonSegmentMemberwtm:PrivateDebtInstrumentMember2022-12-310000776867wtm:PrivateDebtInstrumentMember2022-12-310000776867wtm:OtherFundsMemberwtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMember2022-12-310000776867wtm:OtherFundsMemberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2022-12-310000776867wtm:OtherFundsMemberus-gaap:CorporateNonSegmentMember2022-12-310000776867wtm:OtherFundsMember2022-12-310000776867us-gaap:PrivateEquityFundsMember2023-09-30wtm:fund0000776867us-gaap:HedgeFundsMember2023-09-300000776867wtm:LargestInvestmentMemberwtm:PrivateEquityAndHedgeFundConcentrationRiskMemberus-gaap:InvestmentsMember2023-09-300000776867wtm:LargestInvestmentMemberwtm:PrivateEquityAndHedgeFundConcentrationRiskMemberus-gaap:InvestmentsMember2022-12-310000776867us-gaap:PrivateEquityFundsMemberwtm:AerospaceDefenseGovernmentSectorMember2023-09-300000776867us-gaap:PrivateEquityFundsMemberwtm:AerospaceDefenseGovernmentSectorMember2022-12-310000776867us-gaap:PrivateEquityFundsMemberus-gaap:FinancialServicesSectorMember2023-09-300000776867us-gaap:PrivateEquityFundsMemberus-gaap:FinancialServicesSectorMember2022-12-310000776867us-gaap:RealEstateSectorMemberus-gaap:PrivateEquityFundsMember2023-09-300000776867us-gaap:RealEstateSectorMemberus-gaap:PrivateEquityFundsMember2022-12-310000776867us-gaap:PrivateEquityFundsMember2022-12-310000776867us-gaap:HedgeFundsMemberwtm:HedgeFundLongShortEquityBanksAndFinancialMember2023-09-300000776867us-gaap:HedgeFundsMemberwtm:HedgeFundLongShortEquityBanksAndFinancialMember2022-12-310000776867us-gaap:HedgeFundsMemberwtm:HedgeFundEuropeanSmallMidCapMember2023-09-300000776867us-gaap:HedgeFundsMemberwtm:HedgeFundEuropeanSmallMidCapMember2022-12-310000776867us-gaap:HedgeFundsMember2022-12-310000776867wtm:PrivateEquityFundsAndHedgeFundsMember2023-09-300000776867wtm:PrivateEquityFundsAndHedgeFundsMember2022-12-310000776867us-gaap:HedgeFundsMembersrt:MinimumMember2023-01-012023-09-300000776867us-gaap:HedgeFundsMembersrt:MaximumMember2023-01-012023-09-300000776867wtm:ForeignRegulatoryDepositsMember2023-09-300000776867wtm:ForeignRegulatoryDepositsMember2022-12-310000776867srt:MinimumMemberwtm:InsuranceLinkedSecuritiesFundsMember2023-01-012023-09-300000776867srt:MaximumMemberwtm:InsuranceLinkedSecuritiesFundsMember2023-01-012023-09-300000776867us-gaap:OtherLongTermInvestmentsMember2022-12-310000776867us-gaap:OtherLongTermInvestmentsMember2021-12-310000776867us-gaap:OtherLongTermInvestmentsMember2023-09-300000776867us-gaap:OtherLongTermInvestmentsMember2022-09-300000776867wtm:ValuationTechniqueRecentOrExpectedTransactionPricesMemberus-gaap:FairValueInputsLevel3Member2023-09-300000776867wtm:ValuationTechniqueRecentOrExpectedTransactionPricesMemberus-gaap:FairValueInputsLevel3Member2022-12-310000776867us-gaap:FairValueInputsLevel3Memberwtm:KuduParticipationContractsMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2023-09-300000776867srt:MinimumMemberus-gaap:FairValueInputsLevel3Memberwtm:KuduParticipationContractsMemberus-gaap:ValuationTechniqueDiscountedCashFlowMemberus-gaap:MeasurementInputDiscountRateMember2023-01-012023-09-300000776867srt:MaximumMemberus-gaap:FairValueInputsLevel3Memberwtm:KuduParticipationContractsMemberus-gaap:ValuationTechniqueDiscountedCashFlowMemberus-gaap:MeasurementInputDiscountRateMember2023-01-012023-09-300000776867wtm:MeasurementInputTerminalCashFlowExitMultipleMembersrt:MinimumMemberus-gaap:FairValueInputsLevel3Memberwtm:KuduParticipationContractsMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2023-01-012023-09-300000776867wtm:MeasurementInputTerminalCashFlowExitMultipleMembersrt:MaximumMemberus-gaap:FairValueInputsLevel3Memberwtm:KuduParticipationContractsMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2023-01-012023-09-300000776867us-gaap:FairValueInputsLevel3Memberus-gaap:ValuationTechniqueDiscountedCashFlowMemberwtm:DavidShieldPassportCardMember2023-09-300000776867us-gaap:FairValueInputsLevel3Memberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMemberwtm:DavidShieldPassportCardMember2023-01-012023-09-300000776867us-gaap:FairValueInputsLevel3Memberus-gaap:ValuationTechniqueDiscountedCashFlowMemberwtm:DavidShieldPassportCardMemberus-gaap:MeasurementInputLongTermRevenueGrowthRateMember2023-01-012023-09-300000776867wtm:ElementumHoldingsL.P.Memberus-gaap:FairValueInputsLevel3Memberus-gaap:ValuationTechniqueDiscountedCashFlowMember2023-09-300000776867wtm:ElementumHoldingsL.P.Memberus-gaap:FairValueInputsLevel3Memberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2023-01-012023-09-300000776867wtm:ElementumHoldingsL.P.Memberus-gaap:FairValueInputsLevel3Memberus-gaap:ValuationTechniqueDiscountedCashFlowMemberus-gaap:MeasurementInputLongTermRevenueGrowthRateMember2023-01-012023-09-300000776867wtm:MandatorilyRedeemablePreferredSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:ValuationTechniqueDiscountedCashFlowMember2023-09-300000776867wtm:MandatorilyRedeemablePreferredSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2023-01-012023-09-300000776867wtm:PrivateDebtInstrumentMemberus-gaap:FairValueInputsLevel3Memberus-gaap:ValuationTechniqueDiscountedCashFlowMember2023-09-300000776867srt:MinimumMemberwtm:PrivateDebtInstrumentMemberus-gaap:FairValueInputsLevel3Memberus-gaap:ValuationTechniqueDiscountedCashFlowMemberus-gaap:MeasurementInputDiscountRateMember2023-01-012023-09-300000776867wtm:PrivateDebtInstrumentMembersrt:MaximumMemberus-gaap:FairValueInputsLevel3Memberus-gaap:ValuationTechniqueDiscountedCashFlowMemberus-gaap:MeasurementInputDiscountRateMember2023-01-012023-09-300000776867wtm:MeasurementInputPreTaxDiscountRateMemberus-gaap:FairValueInputsLevel3Memberwtm:KuduParticipationContractsMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2023-01-012023-09-300000776867us-gaap:FairValueInputsLevel3Memberwtm:MeasurementInputPreTaxTerminalCashFlowExitMultipleMemberwtm:KuduParticipationContractsMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2023-01-012023-09-300000776867wtm:KuduParticipationContractsMember2023-01-012023-09-300000776867us-gaap:FairValueInputsLevel3Memberwtm:KuduParticipationContractsMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2022-12-310000776867srt:MinimumMemberus-gaap:FairValueInputsLevel3Memberwtm:KuduParticipationContractsMemberus-gaap:ValuationTechniqueDiscountedCashFlowMemberus-gaap:MeasurementInputDiscountRateMember2022-01-012022-12-310000776867srt:MaximumMemberus-gaap:FairValueInputsLevel3Memberwtm:KuduParticipationContractsMemberus-gaap:ValuationTechniqueDiscountedCashFlowMemberus-gaap:MeasurementInputDiscountRateMember2022-01-012022-12-310000776867wtm:MeasurementInputTerminalCashFlowExitMultipleMembersrt:MinimumMemberus-gaap:FairValueInputsLevel3Memberwtm:KuduParticipationContractsMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2022-01-012022-12-310000776867wtm:MeasurementInputTerminalCashFlowExitMultipleMembersrt:MaximumMemberus-gaap:FairValueInputsLevel3Memberwtm:KuduParticipationContractsMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2022-01-012022-12-310000776867us-gaap:FairValueInputsLevel3Memberus-gaap:ValuationTechniqueDiscountedCashFlowMemberwtm:DavidShieldPassportCardMember2022-12-310000776867us-gaap:FairValueInputsLevel3Memberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMemberwtm:DavidShieldPassportCardMember2022-01-012022-12-310000776867us-gaap:FairValueInputsLevel3Memberus-gaap:ValuationTechniqueDiscountedCashFlowMemberwtm:DavidShieldPassportCardMemberus-gaap:MeasurementInputLongTermRevenueGrowthRateMember2022-01-012022-12-310000776867wtm:ElementumHoldingsL.P.Memberus-gaap:FairValueInputsLevel3Memberus-gaap:ValuationTechniqueDiscountedCashFlowMember2022-12-310000776867wtm:ElementumHoldingsL.P.Memberus-gaap:FairValueInputsLevel3Memberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2022-01-012022-12-310000776867wtm:ElementumHoldingsL.P.Memberus-gaap:FairValueInputsLevel3Memberus-gaap:ValuationTechniqueDiscountedCashFlowMemberus-gaap:MeasurementInputLongTermRevenueGrowthRateMember2022-01-012022-12-310000776867wtm:PrivateDebtInstrumentMemberus-gaap:FairValueInputsLevel3Memberus-gaap:ValuationTechniqueDiscountedCashFlowMember2022-12-310000776867wtm:PrivateDebtInstrumentMemberus-gaap:FairValueInputsLevel3Memberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2022-01-012022-12-310000776867wtm:MeasurementInputPreTaxDiscountRateMemberus-gaap:FairValueInputsLevel3Memberwtm:KuduParticipationContractsMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2022-01-012022-12-310000776867us-gaap:FairValueInputsLevel3Memberwtm:MeasurementInputPreTaxTerminalCashFlowExitMultipleMemberwtm:KuduParticipationContractsMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2022-01-012022-12-310000776867wtm:KuduParticipationContractsMember2022-01-012022-12-310000776867wtm:ValuationTechniqueProbabilityWeightedExpectedReturnMemberus-gaap:FairValueInputsLevel3Memberwtm:KuduParticipationContractsMember2022-12-310000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMemberwtm:ArkInsuranceHoldingsLimitedSegmentMember2023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMemberwtm:ArkInsuranceHoldingsLimitedSegmentMember2022-12-310000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:UnderwritingCapacityMemberus-gaap:OperatingSegmentsMemberwtm:ArkInsuranceHoldingsLimitedSegmentMember2023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:UnderwritingCapacityMemberus-gaap:OperatingSegmentsMemberwtm:ArkInsuranceHoldingsLimitedSegmentMember2022-12-310000776867us-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMemberus-gaap:TradeNamesMember2023-01-012023-09-300000776867us-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMemberus-gaap:TradeNamesMember2023-09-300000776867us-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMemberus-gaap:TradeNamesMember2022-12-310000776867us-gaap:CorporateNonSegmentMemberus-gaap:TradeNamesMember2023-01-012023-09-300000776867us-gaap:CorporateNonSegmentMemberus-gaap:TradeNamesMember2023-09-300000776867us-gaap:CorporateNonSegmentMemberus-gaap:TradeNamesMember2022-12-310000776867us-gaap:CorporateNonSegmentMemberus-gaap:CustomerRelationshipsMember2023-01-012023-09-300000776867us-gaap:CorporateNonSegmentMemberus-gaap:CustomerRelationshipsMember2023-09-300000776867us-gaap:CorporateNonSegmentMemberus-gaap:CustomerRelationshipsMember2022-12-310000776867us-gaap:CorporateNonSegmentMemberus-gaap:OtherIntangibleAssetsMember2023-01-012023-09-300000776867us-gaap:CorporateNonSegmentMemberus-gaap:OtherIntangibleAssetsMember2023-09-300000776867us-gaap:CorporateNonSegmentMemberus-gaap:OtherIntangibleAssetsMember2022-12-310000776867us-gaap:OtherIntangibleAssetsMember2023-09-300000776867us-gaap:OtherIntangibleAssetsMember2022-12-3100007768672023-06-3000007768672022-06-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMember2023-06-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMember2022-06-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMember2022-12-310000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMember2021-12-310000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMember2023-07-012023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMember2022-07-012022-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMember2023-01-012023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMember2022-01-012022-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMember2023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMember2022-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:TPCProvidersMember2023-06-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:TPCProvidersMember2022-06-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:TPCProvidersMember2022-12-310000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:TPCProvidersMember2021-12-310000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:TPCProvidersMember2023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:TPCProvidersMember2022-09-300000776867wtm:SyndicateArkInsuranceHoldingsLimitedMember2020-12-310000776867wtm:SyndicateArkInsuranceHoldingsLimitedMember2021-12-310000776867wtm:SyndicateArkInsuranceHoldingsLimitedMember2019-12-310000776867wtm:ArkInsuranceHoldingsLimitedOutriggerMember2023-07-012023-09-300000776867wtm:ArkInsuranceHoldingsLimitedOutriggerMember2022-07-012022-09-300000776867wtm:ArkInsuranceHoldingsLimitedOutriggerMember2023-01-012023-09-300000776867wtm:ArkInsuranceHoldingsLimitedOutriggerMember2022-01-012022-09-300000776867wtm:ArkInsuranceHoldingsLimitedSegmentMemberwtm:ArkInsuranceHoldingsLimitedOutriggerMember2023-07-012023-09-300000776867wtm:ArkInsuranceHoldingsLimitedSegmentMemberwtm:ArkInsuranceHoldingsLimitedOutriggerMember2023-01-012023-09-300000776867wtm:ArkInsuranceHoldingsLimitedOutriggerMember2023-09-300000776867wtm:ArkInsuranceHoldingsLimitedOutriggerMember2022-12-310000776867wtm:ArkInsuranceHoldingsLimitedSegmentMemberwtm:ArkInsuranceHoldingsLimitedOutriggerMember2023-09-300000776867wtm:TPCProvidersMember2022-12-310000776867srt:AMBestAPlusRatingMemberwtm:ArkInsuranceHoldingsLimitedOutriggerMember2023-09-300000776867srt:AMBestAPlusRatingMemberus-gaap:CededCreditRiskSecuredMemberwtm:ArkInsuranceHoldingsLimitedOutriggerMember2023-09-300000776867srt:AMBestAPlusRatingMemberwtm:ArkInsuranceHoldingsLimitedOutriggerMemberus-gaap:ReinsurerConcentrationRiskMemberus-gaap:ReinsuranceRecoverableMember2023-01-012023-09-300000776867wtm:ArkInsuranceHoldingsLimitedOutriggerMembersrt:AMBestAMinusRatingMember2023-09-300000776867us-gaap:CededCreditRiskSecuredMembersrt:AMBestAMinusRatingMemberwtm:ArkInsuranceHoldingsLimitedOutriggerMember2023-09-300000776867srt:AMBestAMinusRatingMemberwtm:ArkInsuranceHoldingsLimitedOutriggerMemberus-gaap:ReinsurerConcentrationRiskMemberus-gaap:ReinsuranceRecoverableMember2023-01-012023-09-300000776867srt:AMBestBPlusPlusRatingMemberwtm:ArkInsuranceHoldingsLimitedOutriggerMember2023-09-300000776867us-gaap:CededCreditRiskSecuredMembersrt:AMBestBPlusPlusRatingMemberwtm:ArkInsuranceHoldingsLimitedOutriggerMember2023-09-300000776867srt:AMBestBPlusPlusRatingMemberwtm:ArkInsuranceHoldingsLimitedOutriggerMemberus-gaap:ReinsurerConcentrationRiskMemberus-gaap:ReinsuranceRecoverableMember2023-01-012023-09-300000776867us-gaap:CededCreditRiskSecuredMemberwtm:ArkInsuranceHoldingsLimitedOutriggerMember2023-09-300000776867wtm:ArkInsuranceHoldingsLimitedOutriggerMemberus-gaap:ReinsurerConcentrationRiskMemberus-gaap:ReinsuranceRecoverableMember2023-01-012023-09-300000776867wtm:ThirdPointReMemberwtm:ArkInsuranceHoldingsLimitedOutriggerMember2023-09-300000776867wtm:ThirdPointReMemberwtm:ArkInsuranceHoldingsLimitedOutriggerMember2022-12-310000776867wtm:Ark2007SubordinatedNotesMemberus-gaap:SubordinatedDebtMember2023-09-300000776867wtm:Ark2007SubordinatedNotesMemberus-gaap:SubordinatedDebtMember2022-12-310000776867us-gaap:SubordinatedDebtMemberwtm:Ark2021SubordinatedNotesTranche1Member2023-09-300000776867us-gaap:SubordinatedDebtMemberwtm:Ark2021SubordinatedNotesTranche1Member2022-12-310000776867wtm:Ark2021SubordinatedNotesTranche2Memberus-gaap:SubordinatedDebtMember2023-09-300000776867wtm:Ark2021SubordinatedNotesTranche2Memberus-gaap:SubordinatedDebtMember2022-12-310000776867wtm:Ark2021SubordinatedNotesTranche3Memberus-gaap:SubordinatedDebtMember2023-09-300000776867wtm:Ark2021SubordinatedNotesTranche3Memberus-gaap:SubordinatedDebtMember2022-12-310000776867us-gaap:SubordinatedDebtMemberwtm:Ark2021SubordinatedNotesMember2023-09-300000776867us-gaap:SubordinatedDebtMemberwtm:Ark2021SubordinatedNotesMember2022-12-310000776867wtm:ArkInsuranceHoldingsLimitedMemberus-gaap:SubordinatedDebtMember2023-09-300000776867wtm:ArkInsuranceHoldingsLimitedMemberus-gaap:SubordinatedDebtMember2022-12-310000776867wtm:KuduCreditFacilityMember2023-09-300000776867wtm:KuduCreditFacilityMember2022-12-310000776867wtm:OtherOperationsDebtMemberus-gaap:SecuredDebtMember2023-09-300000776867wtm:OtherOperationsDebtMemberus-gaap:SecuredDebtMember2022-12-310000776867wtm:OtherOperationsDebtMember2023-09-300000776867wtm:OtherOperationsDebtMember2022-12-310000776867wtm:HGGlobalSeniorNotesMemberus-gaap:SeniorNotesMember2022-04-290000776867us-gaap:SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMemberwtm:HGGlobalSeniorNotesMemberus-gaap:SeniorNotesMember2022-04-292022-04-290000776867wtm:HGGlobalSeniorNotesMemberus-gaap:SeniorNotesMember2022-04-292022-04-290000776867wtm:HGGlobalSeniorNotesMemberus-gaap:SeniorNotesMember2022-04-300000776867wtm:SubsidiaryHGGlobalMemberus-gaap:InterestRateCapMember2022-06-160000776867wtm:HGGlobalSeniorNotesMemberus-gaap:SeniorNotesMember2022-06-160000776867wtm:HGGlobalSeniorNotesMemberus-gaap:SeniorNotesMember2023-01-012023-09-300000776867us-gaap:JuniorSubordinatedDebtMemberwtm:Ark2007SubordinatedNotesMember2007-03-310000776867wtm:LondonInterbankOfferedRateLIBOR1Memberus-gaap:JuniorSubordinatedDebtMemberwtm:Ark2007SubordinatedNotesMember2007-03-012007-03-310000776867us-gaap:JuniorSubordinatedDebtMemberwtm:Ark2007SubordinatedNotesMember2023-09-300000776867us-gaap:SubordinatedDebtMemberwtm:Ark2021SubordinatedNotesMember2021-09-300000776867us-gaap:SubordinatedDebtMemberwtm:Ark2021SubordinatedNotesMember2021-07-012021-09-300000776867us-gaap:SubordinatedDebtMemberwtm:Ark2021SubordinatedNotesTranche1Member2021-07-13iso4217:EUR0000776867wtm:EuroInterbankOfferedRateEURIBORMemberus-gaap:SubordinatedDebtMemberwtm:Ark2021SubordinatedNotesTranche1Member2021-07-012021-07-310000776867wtm:Ark2021SubordinatedNotesTranche2Memberus-gaap:SubordinatedDebtMember2021-08-110000776867wtm:LondonInterbankOfferedRateLIBOR1Memberwtm:Ark2021SubordinatedNotesTranche2Memberus-gaap:SubordinatedDebtMember2021-08-012021-08-310000776867wtm:Ark2021SubordinatedNotesTranche3Memberus-gaap:SubordinatedDebtMember2021-09-080000776867wtm:Ark2021SubordinatedNotesTranche3Memberwtm:LondonInterbankOfferedRateLIBOR1Memberus-gaap:SubordinatedDebtMember2021-09-082021-09-080000776867wtm:Ark2021SubordinatedNotesTranche3Memberus-gaap:SubordinatedDebtMember2023-01-012023-09-300000776867wtm:Ark2021SubordinatedNotesTranche3Memberus-gaap:SubordinatedDebtMember2021-09-012021-09-300000776867us-gaap:LetterOfCreditMemberus-gaap:LineOfCreditMemberwtm:INGLOCFacilityMember2021-12-31wtm:letterOfCredit0000776867us-gaap:LetterOfCreditMemberus-gaap:LineOfCreditMemberwtm:CitibankLOCFacilityMember2021-12-310000776867us-gaap:LetterOfCreditMemberus-gaap:LineOfCreditMemberwtm:LloydsLOCFacilityMember2022-09-300000776867us-gaap:LetterOfCreditMemberus-gaap:LineOfCreditMemberwtm:CitibankLOCFacilityMember2023-09-300000776867us-gaap:LetterOfCreditMemberus-gaap:LineOfCreditMemberwtm:LloydsLOCFacilityMember2023-09-300000776867wtm:LondonInterbankOfferedRateLIBOR1Memberwtm:KuduCreditFacilityMemberus-gaap:SecuredDebtMember2023-01-012023-06-300000776867wtm:KuduCreditFacilityMemberus-gaap:SecuredDebtMember2023-06-300000776867us-gaap:SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMemberwtm:KuduCreditFacilityMemberus-gaap:SecuredDebtMember2023-07-012023-07-010000776867wtm:KuduCreditFacilityMemberus-gaap:SecuredDebtMember2023-07-010000776867wtm:KuduCreditFacilityMemberwtm:DebtCovenantPeriod1Memberus-gaap:SecuredDebtMember2023-09-300000776867wtm:DebtCovenantPeriod2Memberwtm:KuduCreditFacilityMemberus-gaap:SecuredDebtMember2023-09-300000776867wtm:DebtCovenantPeriod3Memberwtm:KuduCreditFacilityMemberus-gaap:SecuredDebtMember2023-09-300000776867wtm:DebtCovenantPeriod4Memberwtm:KuduCreditFacilityMemberus-gaap:SecuredDebtMember2023-09-300000776867wtm:KuduCreditFacilityMemberwtm:DebtCovenantPeriod5Memberus-gaap:SecuredDebtMember2023-09-300000776867wtm:KuduCreditFacilityMemberus-gaap:SecuredDebtMember2022-06-300000776867wtm:KuduCreditFacilityMemberus-gaap:SecuredDebtMember2021-12-310000776867wtm:KuduCreditFacilityMemberus-gaap:SecuredDebtMember2023-07-012023-09-300000776867wtm:KuduCreditFacilityMemberus-gaap:SecuredDebtMember2022-07-012022-09-300000776867wtm:KuduCreditFacilityMemberus-gaap:SecuredDebtMember2023-01-012023-09-300000776867wtm:KuduCreditFacilityMemberus-gaap:SecuredDebtMember2022-01-012022-09-300000776867wtm:KuduCreditFacilityMemberus-gaap:SecuredDebtMember2022-09-30wtm:credit_facility0000776867wtm:SubsidiaryHGGlobalMemberus-gaap:InterestRateCapMemberus-gaap:SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember2022-06-160000776867wtm:SubsidiaryHGGlobalMemberus-gaap:InterestRateCapMemberus-gaap:InterestExpenseMember2023-07-012023-09-300000776867wtm:SubsidiaryHGGlobalMemberus-gaap:InterestRateCapMemberus-gaap:InterestExpenseMember2023-01-012023-09-300000776867wtm:SubsidiaryHGGlobalMemberus-gaap:InterestRateCapMemberus-gaap:InterestExpenseMember2022-07-012022-09-300000776867wtm:SubsidiaryHGGlobalMemberus-gaap:InterestRateCapMemberus-gaap:InterestExpenseMember2022-01-012022-09-300000776867wtm:SubsidiaryHGGlobalMemberus-gaap:InterestRateCapMember2023-07-012023-09-300000776867wtm:SubsidiaryHGGlobalMemberus-gaap:InterestRateCapMember2023-01-012023-09-300000776867wtm:SubsidiaryHGGlobalMemberus-gaap:InterestRateCapMember2023-09-300000776867wtm:SubsidiaryHGGlobalMemberus-gaap:InterestRateCapMember2022-12-310000776867wtm:SubsidiaryHGGlobalMember2023-09-300000776867wtm:VariableInterestEntityPrimaryBeneficiaryBuildAmericaMutualAssuranceCompanyMemberwtm:FidusReLtd.Member2018-01-012018-12-310000776867srt:MinimumMemberwtm:FidusReLtd.Member2018-01-012018-12-310000776867srt:MaximumMemberwtm:FidusReLtd.Member2018-01-012018-12-310000776867wtm:A2018CoveredPortfolioMemberwtm:VariableInterestEntityPrimaryBeneficiaryBuildAmericaMutualAssuranceCompanyMemberwtm:FidusReLtd.Member2023-01-012023-09-300000776867wtm:VariableInterestEntityPrimaryBeneficiaryBuildAmericaMutualAssuranceCompanyMemberwtm:FidusReLtd.Member2021-01-012021-12-310000776867srt:MinimumMemberwtm:FidusReLtd.Member2021-01-012021-12-310000776867srt:MaximumMemberwtm:FidusReLtd.Member2021-01-012021-12-310000776867wtm:VariableInterestEntityPrimaryBeneficiaryBuildAmericaMutualAssuranceCompanyMemberwtm:A2021CoveredPortfolioMemberwtm:FidusReLtd.Member2023-01-012023-09-300000776867wtm:VariableInterestEntityPrimaryBeneficiaryBuildAmericaMutualAssuranceCompanyMemberwtm:FidusReLtd.Member2022-01-012022-12-310000776867srt:MinimumMemberwtm:FidusReLtd.Member2022-01-012022-12-310000776867srt:MaximumMemberwtm:FidusReLtd.Member2022-01-012022-12-310000776867wtm:A2022CoveredPortfolioMemberwtm:VariableInterestEntityPrimaryBeneficiaryBuildAmericaMutualAssuranceCompanyMemberwtm:FidusReLtd.Member2023-01-012023-09-300000776867wtm:VariableInterestEntityPrimaryBeneficiaryBuildAmericaMutualAssuranceCompanyMemberwtm:FidusReLtd.Member2023-01-012023-09-300000776867wtm:SubsidiaryHGGlobalMemberwtm:Regulation114Member2023-09-300000776867wtm:SubsidiaryHGGlobalMemberwtm:Regulation114Member2022-12-310000776867wtm:SubsidiaryHGGlobalMemberwtm:SupplementalTrustMember2023-09-300000776867wtm:SubsidiaryHGGlobalMemberwtm:SupplementalTrustMember2022-12-310000776867wtm:SurplusNotesMemberwtm:BAMSurplusNotesMemberus-gaap:UsTreasuryUstInterestRateMember2023-01-012023-09-300000776867srt:ScenarioForecastMemberwtm:SurplusNotesMemberwtm:BAMSurplusNotesMemberus-gaap:UsTreasuryUstInterestRateMember2023-12-310000776867srt:ScenarioForecastMemberwtm:SurplusNotesMemberwtm:BAMSurplusNotesMemberus-gaap:UsTreasuryUstInterestRateMember2025-01-010000776867wtm:SurplusNotesMemberwtm:BAMSurplusNotesMember2022-12-012022-12-310000776867wtm:SurplusNotesMemberwtm:BAMSurplusNotesMember2022-12-310000776867wtm:SurplusNotesMemberwtm:BAMSurplusNotesMember2023-07-012023-09-300000776867wtm:SurplusNotesMemberwtm:BAMSurplusNotesMember2023-01-012023-09-300000776867wtm:SurplusNotesMemberwtm:BAMSurplusNotesMember2022-01-012022-09-300000776867wtm:SurplusNotesMemberwtm:BAMSurplusNotesMember2022-07-012022-09-300000776867wtm:SurplusNotesMemberwtm:BAMSurplusNotesMember2023-09-300000776867wtm:BuildAmericaMutualAssuranceCompanyMember2023-09-30wtm:contract0000776867wtm:BuildAmericaMutualAssuranceCompanyMember2022-12-310000776867wtm:BuildAmericaMutualAssuranceCompanyMember2023-01-012023-09-300000776867wtm:BuildAmericaMutualAssuranceCompanyMember2022-01-012022-12-310000776867wtm:VariableInterestEntityPrimaryBeneficiaryBuildAmericaMutualAssuranceCompanyMember2023-09-300000776867wtm:HGGlobalBAMSegmentMember2023-07-012023-09-300000776867wtm:HGGlobalBAMSegmentMember2022-07-012022-09-300000776867wtm:HGGlobalBAMSegmentMember2023-01-012023-09-300000776867wtm:HGGlobalBAMSegmentMember2022-01-012022-09-300000776867wtm:VariableInterestEntityPrimaryBeneficiaryBuildAmericaMutualAssuranceCompanyMember2022-09-300000776867us-gaap:PerformanceSharesMember2023-01-012023-09-300000776867us-gaap:PerformanceSharesMembersrt:MinimumMember2023-01-012023-09-300000776867us-gaap:PerformanceSharesMembersrt:MaximumMember2023-01-012023-09-300000776867us-gaap:PerformanceSharesMember2023-03-012023-03-310000776867us-gaap:PerformanceSharesMember2022-03-012022-03-310000776867us-gaap:PerformanceSharesMember2019-01-012021-12-310000776867us-gaap:PerformanceSharesMember2023-09-300000776867wtm:PerformancePeriodOneMember2023-09-300000776867wtm:PerformancePeriodTwoMember2023-09-300000776867wtm:PerformancePeriodThreeMember2023-09-300000776867us-gaap:RestrictedStockMember2023-01-012023-09-300000776867us-gaap:RestrictedStockMember2023-06-300000776867us-gaap:RestrictedStockMember2022-06-300000776867us-gaap:RestrictedStockMember2022-12-310000776867us-gaap:RestrictedStockMember2021-12-310000776867us-gaap:RestrictedStockMember2023-07-012023-09-300000776867us-gaap:RestrictedStockMember2022-07-012022-09-300000776867us-gaap:RestrictedStockMember2022-01-012022-09-300000776867us-gaap:RestrictedStockMember2023-09-300000776867us-gaap:RestrictedStockMember2022-09-300000776867wtm:SubsidiaryHGGlobalMember2023-09-300000776867wtm:SubsidiaryHGGlobalMember2022-12-310000776867wtm:SubsidiaryHGGlobalMember2022-12-310000776867wtm:SubsidiaryArkInsuranceHoldingsLimitedMember2023-09-300000776867wtm:SubsidiaryArkInsuranceHoldingsLimitedMember2022-12-310000776867wtm:SubsidiaryKuduInvestmentManagementLLCMember2023-09-300000776867wtm:SubsidiaryKuduInvestmentManagementLLCMember2022-12-310000776867wtm:OtherNoncontrollingInterestMember2023-09-300000776867wtm:OtherNoncontrollingInterestMember2022-12-310000776867srt:ConsolidatedEntityExcludingVariableInterestEntitiesVIEMember2023-09-300000776867srt:ConsolidatedEntityExcludingVariableInterestEntitiesVIEMember2022-12-310000776867wtm:BuildAmericaMutualAssuranceCompanyMember2023-09-300000776867us-gaap:VariableInterestEntityPrimaryBeneficiaryMember2023-09-300000776867wtm:BuildAmericaMutualAssuranceCompanyMember2022-12-310000776867us-gaap:VariableInterestEntityPrimaryBeneficiaryMember2022-12-310000776867wtm:HGGlobalSegmentMemberwtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMember2023-07-012023-09-300000776867wtm:BAMSegmentMemberwtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMember2023-07-012023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMemberwtm:ArkInsuranceHoldingsLimitedSegmentMember2023-07-012023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:WMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMember2023-07-012023-09-300000776867wtm:HGGlobalSegmentMemberwtm:HGGlobalBAMSegmentMemberwtm:InvestmentsExcludingMediaAlphaMemberus-gaap:OperatingSegmentsMember2023-07-012023-09-300000776867wtm:BAMSegmentMemberwtm:HGGlobalBAMSegmentMemberwtm:InvestmentsExcludingMediaAlphaMemberus-gaap:OperatingSegmentsMember2023-07-012023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:InvestmentsExcludingMediaAlphaMemberus-gaap:OperatingSegmentsMemberwtm:ArkInsuranceHoldingsLimitedSegmentMember2023-07-012023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:InvestmentsExcludingMediaAlphaMemberwtm:WMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMember2023-07-012023-09-300000776867wtm:InvestmentsExcludingMediaAlphaMemberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2023-07-012023-09-300000776867wtm:InvestmentsExcludingMediaAlphaMember2023-07-012023-09-300000776867wtm:HGGlobalSegmentMemberwtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMemberwtm:MediaAlphaMember2023-07-012023-09-300000776867wtm:BAMSegmentMemberwtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMemberwtm:MediaAlphaMember2023-07-012023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMemberwtm:MediaAlphaMemberwtm:ArkInsuranceHoldingsLimitedSegmentMember2023-07-012023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:WMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMemberwtm:MediaAlphaMember2023-07-012023-09-300000776867us-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMemberwtm:MediaAlphaMember2023-07-012023-09-300000776867wtm:MediaAlphaMember2023-07-012023-09-300000776867wtm:HGGlobalSegmentMemberwtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMember2022-07-012022-09-300000776867wtm:BAMSegmentMemberwtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMember2022-07-012022-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMemberwtm:ArkInsuranceHoldingsLimitedSegmentMember2022-07-012022-09-300000776867wtm:HGGlobalSegmentMemberwtm:HGGlobalBAMSegmentMemberwtm:InvestmentsExcludingMediaAlphaMemberus-gaap:OperatingSegmentsMember2022-07-012022-09-300000776867wtm:BAMSegmentMemberwtm:HGGlobalBAMSegmentMemberwtm:InvestmentsExcludingMediaAlphaMemberus-gaap:OperatingSegmentsMember2022-07-012022-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:InvestmentsExcludingMediaAlphaMemberus-gaap:OperatingSegmentsMemberwtm:ArkInsuranceHoldingsLimitedSegmentMember2022-07-012022-09-300000776867wtm:InvestmentsExcludingMediaAlphaMemberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2022-07-012022-09-300000776867wtm:InvestmentsExcludingMediaAlphaMember2022-07-012022-09-300000776867wtm:HGGlobalSegmentMemberwtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMemberwtm:MediaAlphaMember2022-07-012022-09-300000776867wtm:BAMSegmentMemberwtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMemberwtm:MediaAlphaMember2022-07-012022-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMemberwtm:MediaAlphaMemberwtm:ArkInsuranceHoldingsLimitedSegmentMember2022-07-012022-09-300000776867us-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMemberwtm:MediaAlphaMember2022-07-012022-09-300000776867wtm:MediaAlphaMember2022-07-012022-09-300000776867wtm:HGGlobalSegmentMemberwtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMember2023-01-012023-09-300000776867wtm:BAMSegmentMemberwtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMember2023-01-012023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMemberwtm:ArkInsuranceHoldingsLimitedSegmentMember2023-01-012023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:WMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMember2023-01-012023-09-300000776867wtm:HGGlobalSegmentMemberwtm:HGGlobalBAMSegmentMemberwtm:InvestmentsExcludingMediaAlphaMemberus-gaap:OperatingSegmentsMember2023-01-012023-09-300000776867wtm:BAMSegmentMemberwtm:HGGlobalBAMSegmentMemberwtm:InvestmentsExcludingMediaAlphaMemberus-gaap:OperatingSegmentsMember2023-01-012023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:InvestmentsExcludingMediaAlphaMemberus-gaap:OperatingSegmentsMemberwtm:ArkInsuranceHoldingsLimitedSegmentMember2023-01-012023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:InvestmentsExcludingMediaAlphaMemberwtm:WMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMember2023-01-012023-09-300000776867wtm:InvestmentsExcludingMediaAlphaMemberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2023-01-012023-09-300000776867wtm:HGGlobalSegmentMemberwtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMemberwtm:MediaAlphaMember2023-01-012023-09-300000776867wtm:BAMSegmentMemberwtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMemberwtm:MediaAlphaMember2023-01-012023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMemberwtm:MediaAlphaMemberwtm:ArkInsuranceHoldingsLimitedSegmentMember2023-01-012023-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:WMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMemberwtm:MediaAlphaMember2023-01-012023-09-300000776867us-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMemberwtm:MediaAlphaMember2023-01-012023-09-300000776867wtm:HGGlobalSegmentMemberwtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMember2022-01-012022-09-300000776867wtm:BAMSegmentMemberwtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMember2022-01-012022-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMemberwtm:ArkInsuranceHoldingsLimitedSegmentMember2022-01-012022-09-300000776867wtm:HGGlobalSegmentMemberwtm:HGGlobalBAMSegmentMemberwtm:InvestmentsExcludingMediaAlphaMemberus-gaap:OperatingSegmentsMember2022-01-012022-09-300000776867wtm:BAMSegmentMemberwtm:HGGlobalBAMSegmentMemberwtm:InvestmentsExcludingMediaAlphaMemberus-gaap:OperatingSegmentsMember2022-01-012022-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberwtm:InvestmentsExcludingMediaAlphaMemberus-gaap:OperatingSegmentsMemberwtm:ArkInsuranceHoldingsLimitedSegmentMember2022-01-012022-09-300000776867wtm:InvestmentsExcludingMediaAlphaMemberus-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMember2022-01-012022-09-300000776867wtm:HGGlobalSegmentMemberwtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMemberwtm:MediaAlphaMember2022-01-012022-09-300000776867wtm:BAMSegmentMemberwtm:HGGlobalBAMSegmentMemberus-gaap:OperatingSegmentsMemberwtm:MediaAlphaMember2022-01-012022-09-300000776867wtm:ArkInsuranceHoldingsLimitedWMOutriggerReSegmentMemberus-gaap:OperatingSegmentsMemberwtm:MediaAlphaMemberwtm:ArkInsuranceHoldingsLimitedSegmentMember2022-01-012022-09-300000776867us-gaap:OperatingSegmentsMemberwtm:KuduInvestmentManagementLLCSegmentMemberwtm:MediaAlphaMember2022-01-012022-09-300000776867wtm:PassportCardDavidShieldMemberus-gaap:VariableInterestEntityNotPrimaryBeneficiaryMember2023-01-012023-09-300000776867wtm:PassportCardDavidShieldMemberus-gaap:VariableInterestEntityNotPrimaryBeneficiaryMember2023-09-300000776867wtm:ElementumHoldingsL.P.Memberus-gaap:VariableInterestEntityNotPrimaryBeneficiaryMember2023-01-012023-09-300000776867wtm:ElementumHoldingsL.P.Memberus-gaap:VariableInterestEntityNotPrimaryBeneficiaryMember2023-09-300000776867us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberwtm:LimitedPartnershipsMember2023-09-300000776867srt:MinimumMemberwtm:KuduParticipationContractsMember2023-09-300000776867srt:MaximumMemberwtm:KuduParticipationContractsMember2023-09-300000776867wtm:KuduParticipationContractsMember2023-09-300000776867srt:MinimumMemberwtm:KuduParticipationContractsMember2022-12-310000776867srt:MaximumMemberwtm:KuduParticipationContractsMember2022-12-310000776867wtm:KuduParticipationContractsMember2022-12-310000776867wtm:PassportCardDavidShieldMember2023-09-300000776867wtm:PassportCardDavidShieldMember2022-12-310000776867wtm:ElementumHoldingsL.P.Member2023-09-300000776867wtm:ElementumHoldingsL.P.Member2022-12-310000776867wtm:EquityMethodEligibleInvestmentsLessThanFiftyPercentMember2023-09-300000776867wtm:EquityMethodEligibleInvestmentsLessThanFiftyPercentMember2022-12-310000776867wtm:EquityMethodEligibleInvestmentsGreaterThanFiftyPercentMember2023-09-300000776867wtm:EquityMethodEligibleInvestmentsGreaterThanFiftyPercentMember2022-12-310000776867wtm:HGGlobalSeniorNotesMember2023-09-300000776867wtm:HGGlobalSeniorNotesMember2022-12-310000776867wtm:Ark2007SubordinatedNotesMember2023-09-300000776867wtm:Ark2007SubordinatedNotesMember2022-12-310000776867wtm:Ark2021SubordinatedNotesMember2023-09-300000776867wtm:Ark2021SubordinatedNotesMember2022-12-310000776867wtm:NSMInsuranceGroupMemberus-gaap:DiscontinuedOperationsDisposedOfBySaleMemberwtm:CommissionsRevenueMember2022-07-012022-09-300000776867wtm:NSMInsuranceGroupMemberus-gaap:DiscontinuedOperationsDisposedOfBySaleMemberwtm:CommissionsRevenueMember2022-01-012022-09-300000776867wtm:NSMInsuranceGroupMemberus-gaap:DiscontinuedOperationsDisposedOfBySaleMemberwtm:OtherRevenueMember2022-07-012022-09-300000776867wtm:NSMInsuranceGroupMemberus-gaap:DiscontinuedOperationsDisposedOfBySaleMemberwtm:OtherRevenueMember2022-01-012022-09-300000776867wtm:NSMInsuranceGroupMemberus-gaap:DiscontinuedOperationsDisposedOfBySaleMember2022-07-012022-09-300000776867wtm:NSMInsuranceGroupMemberus-gaap:DiscontinuedOperationsDisposedOfBySaleMember2022-01-012022-09-300000776867us-gaap:SubsequentEventMemberwtm:BambooIDE8InsuranceServicesLLCMember2023-10-190000776867us-gaap:SubsequentEventMemberwtm:BambooIDE8InsuranceServicesLLCMember2023-10-192023-10-19

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
 
FORM 10-Q
    QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
 
For the period ended September 30, 2023
 
OR
 
         TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
 
For the transition period from          to         
Commission file number 1-8993

WHITE MOUNTAINS INSURANCE GROUP, LTD.
(Exact name of Registrant as specified in its charter)
Bermuda 
(State or other jurisdiction of incorporation or organization) 94-2708455
23 South Main Street, Suite 3B (I.R.S. Employer Identification No.)
Hanover, 03755-2053
New Hampshire(Zip Code)
(Address of principal executive offices) 
 
Registrant’s telephone number, including area code: (603640-2200
 Securities registered pursuant to Section 12(b) of the Act:
Title of each classTrading Symbol(s)Name of each exchange on which registered
Common Shares, par value $1.00 per shareWTMNew York Stock Exchange
WTM.BHBermuda Stock Exchange
Indicate by check mark whether the Registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the Registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes   ý   No   
 
Indicate by check mark whether the Registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the Registrant was required to submit such files). Yes   ý    No   
 
Indicate by check mark whether the Registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company.  See the definitions of “large accelerated filer,” “accelerated filer”, “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.
Large accelerated filerýAccelerated filerNon-accelerated filer
Smaller reporting companyEmerging growth company

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  o
 
Indicate by check mark whether the Registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes     No  ý

As of November 2, 2023, 2,560,452 common shares with a par value of $1.00 per share were outstanding (which includes 37,595 restricted common shares that were not vested at such date).




WHITE MOUNTAINS INSURANCE GROUP, LTD.

Table of Contents
 
  Page No.
   
 
   
 
   
 
Consolidated Balance Sheets, September 30, 2023 and December 31, 2022
  
 
 
     Three and Nine Months Ended September 30, 2023 and 2022
 
 
     Three and Nine Months Ended September 30, 2023 and 2022
 
Consolidated Statements of Cash Flows, Nine Months Ended September 30, 2023 and 2022
  
 
  
  
 
Results of Operations for the Three and Nine Months Ended September 30, 2023 and 2022
  
 
  
 
 
  
 
  
  
  
  
  





Part I.FINANCIAL INFORMATION.
Item 1.Financial Statements
WHITE MOUNTAINS INSURANCE GROUP, LTD.
CONSOLIDATED BALANCE SHEETS
(Unaudited)
Millions, except share and per share amountsSeptember 30, 2023December 31, 2022
Assets
Financial Guarantee (HG Global/BAM)
Fixed maturity investments, at fair value$932.2 $909.9 
Short-term investments, at fair value80.1 65.9 
Total investments1,012.3 975.8 
Cash4.9 18.2 
Insurance premiums receivable5.5 6.6 
Deferred acquisition costs38.5 36.0 
Other assets22.2 21.9 
Total Financial Guarantee assets1,083.4 1,058.5 
P&C Insurance and Reinsurance (Ark/WM Outrigger)
Fixed maturity investments, at fair value775.0 772.8 
Common equity securities, at fair value384.9 334.6 
Short-term investments, at fair value850.0 484.6 
Other long-term investments416.6 373.6 
Total investments2,426.5 1,965.6 
Cash129.6 101.5 
Reinsurance recoverables538.4 595.3 
Insurance premiums receivable781.6 544.1 
Deferred acquisition costs178.7 127.2 
Goodwill and other intangible assets292.5 292.5 
Other assets66.9 65.2 
Total P&C Insurance and Reinsurance assets4,414.2 3,691.4 
Asset Management (Kudu)
     Short-term investments, at fair value17.3  
     Other long-term investments780.7 695.9 
Total investments798.0 695.9 
     Cash (restricted $0.0 and $12.2)
5.4 101.4 
     Accrued investment income15.8 12.4 
     Goodwill and other intangible assets8.4 8.6 
     Other assets8.3 7.6 
Total Asset Management assets835.9 825.9 
Other Operations
     Fixed maturity investments, at fair value270.7 238.2 
     Common equity securities, at fair value252.1 333.8 
Investment in MediaAlpha, at fair value188.8 168.6 
     Short-term investments, at fair value215.5 373.6 
     Other long-term investments698.5 418.5 
     Total investments1,625.6 1,532.7 
     Cash22.9 33.9 
     Goodwill and other intangible assets71.2 91.3 
     Other assets89.6 155.6 
     Total Other Operations assets1,809.3 1,813.5 
Total assets$8,142.8 $7,389.3 
See Notes to Consolidated Financial Statements
1





CONSOLIDATED BALANCE SHEETS (CONTINUED)
(Unaudited)
Millions, except share and per share amountsSeptember 30, 2023December 31, 2022
Liabilities
Financial Guarantee (HG Global/BAM)
Unearned insurance premiums$312.3 $298.3 
Debt146.8 146.5 
Accrued incentive compensation19.9 28.0 
Other liabilities40.0 29.0 
Total Financial Guarantee liabilities519.0 501.8 
P&C Insurance and Reinsurance (Ark/WM Outrigger)
Loss and loss adjustment expense reserves1,571.8 1,296.5 
Unearned insurance premiums984.6 623.2 
Debt184.6 183.7 
Reinsurance payable146.3 251.1 
Contingent consideration62.1 45.3 
Other liabilities132.0 122.3 
Total P&C Insurance and Reinsurance liabilities3,081.4 2,522.1 
Asset Management (Kudu)
Debt203.7 208.3 
Other liabilities53.6 65.0 
Total Asset Management liabilities257.3 273.3 
Other Operations
Debt29.6 36.7 
Accrued incentive compensation64.0 86.1 
Other liabilities27.3 34.3 
Total Other Operations liabilities120.9 157.1 
Total liabilities3,978.6 3,454.3 
Equity
White Mountains’s common shareholders’ equity
White Mountains’s common shares at $1 par value per share—authorized 50,000,000
   shares; issued and outstanding 2,560,452 and 2,572,156 shares
2.6 2.6 
Paid-in surplus544.9536.0
Retained earnings3,404.3 3,211.8 
Accumulated other comprehensive income (loss), after-tax:
Net unrealized gains (losses) from foreign currency translation and interest rate swap(2.7)(3.5)
Total White Mountains’s common shareholders’ equity3,949.1 3,746.9 
Noncontrolling interests215.1 188.1 
Total equity4,164.2 3,935.0 
Total liabilities and equity$8,142.8 $7,389.3 
See Notes to Consolidated Financial Statements
2


WHITE MOUNTAINS INSURANCE GROUP, LTD.
CONSOLIDATED STATEMENTS OF OPERATIONS
(Unaudited)

Three Months Ended September 30,Nine Months Ended September 30,
Millions2023202220232022
Revenues:
Financial Guarantee (HG Global/BAM)
Earned insurance premiums$7.9 $7.1 $23.3 $26.0 
Net investment income8.1 5.7 22.9 15.1 
Net realized and unrealized investment gains (losses)(24.1)(38.8)(17.0)(114.0)
Other revenues.7 1.3 2.0 3.7 
Total Financial Guarantee revenues(7.4)(24.7)31.2 (69.2)
P&C Insurance and Reinsurance (Ark/WM Outrigger)
Earned insurance premiums498.9 346.1 1,047.3 757.8 
Net investment income16.9 4.9 41.2 9.7 
Net realized and unrealized investment gains (losses)(6.6)(14.4)35.9 (76.5)
Other revenues3.6 6.6 (1.1)10.1 
Total P&C Insurance and Reinsurance revenues512.8 343.2 1,123.3 701.1 
Asset Management (Kudu)
Net investment income15.1 14.8 44.0 41.2 
Net realized and unrealized investment gains (losses)11.2 41.1 45.4 45.8 
Total Asset Management revenues26.3 55.9 89.4 87.0 
Other Operations
   Net investment income8.0 8.5 22.0 13.6 
   Net realized and unrealized investment gains (losses)8.0 (17.3)125.8 2.8 
   Net realized and unrealized investment gains (losses) from
      investment in MediaAlpha
(46.8)(18.6)(38.9)(113.3)
   Commission revenues3.5 3.2 10.0 8.7 
   Other revenues15.2 33.0 67.1 89.6 
Total Other Operations revenues(12.1)8.8 186.0 1.4 
Total revenues$519.6 $383.2 $1,429.9 $720.3 
See Notes to Consolidated Financial Statements
3


CONSOLIDATED STATEMENTS OF OPERATIONS (CONTINUED)
(Unaudited)

Three Months Ended September 30,Nine Months Ended September 30,
Millions2023202220232022
Expenses:
Financial Guarantee (HG Global/BAM)
Acquisition expenses$2.1 $1.7 $6.3 $9.5 
General and administrative expenses17.5 15.8 49.7 49.5 
Interest expense3.8 2.0 10.8 5.4 
Total Financial Guarantee expenses23.4 19.5 66.8 64.4 
P&C Insurance and Reinsurance (Ark/WM Outrigger)
Loss and loss adjustment expenses265.8 213.7 581.1 456.2 
Acquisition expenses90.3 74.8 211.5 174.9 
General and administrative expenses35.4 24.2 105.5 74.9 
Change in fair value of contingent consideration17.0 2.716.8 4.9 
Interest expense5.5 3.7 15.7 10.6 
Total P&C Insurance and Reinsurance expenses414.0 319.1 930.6 721.5 
Asset Management (Kudu)
General and administrative expenses4.5 4.5 12.3 10.4 
Interest expense5.5 4.2 15.5 10.3 
Total Asset Management expenses10.0 8.7 27.8 20.7 
Other Operations
   Cost of sales8.0 25.0 33.5 68.8 
   General and administrative expenses42.2 41.3 130.7 122.1 
   Interest expense.9 .6 2.9 1.2 
Total Other Operations expenses51.1 66.9 167.1 192.1 
Total expenses498.5 414.2 1,192.3 998.7 
Pre-tax income (loss) from continuing operations21.1 (31.0)237.6 (278.4)
   Income tax (expense) benefit(7.3)7.4 (19.4)26.1 
Net income (loss) from continuing operations13.8 (23.6)218.2 (252.3)
Net income (loss) from discontinued operations, net of tax -
   NSM Group
 6.3  16.4 
Net gain (loss) from sale of discontinued operations, net of tax -
   NSM Group
 886.8  886.8 
Net income (loss)13.8 869.5 218.2 650.9 
   Net (income) loss attributable to noncontrolling interests9.8 18.7 4.5 101.5 
Net income (loss) attributable to White Mountains’s
   common shareholders
$23.6 $888.2 $222.7 $752.4 
See Notes to Consolidated Financial Statements
4


WHITE MOUNTAINS INSURANCE GROUP, LTD.
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
(Unaudited)

Three Months Ended September 30,Nine Months Ended September 30,
Millions2023202220232022
Net income (loss) attributable to White Mountains’s
   common shareholders
$23.6 $888.2 $222.7 $752.4 
Other comprehensive income, net of tax:
Other comprehensive income (loss), net of tax(1.7)(1.4).9 (3.0)
Other comprehensive income (loss) from discontinued
   operations, net of tax - NSM Group
 .7  (5.2)
Net gain (loss) from foreign currency translation from sale of
   discontinued operations, net of tax - NSM Group
 2.9  2.9 
Comprehensive income (loss) 21.9 890.4 223.6 747.1 
Other comprehensive (income) loss attributable to
   noncontrolling interests
.7 (.3)(.1).4 
Comprehensive income (loss) attributable to
   White Mountains’s common shareholders
$22.6 $890.1 $223.5 $747.5 

Earnings (loss) per share attributable to White Mountains’s common shareholders:
Basic earnings (loss) per share
Continuing operations$9.19 $(1.66)$86.82 $(50.73)
Discontinued operations 308.59  304.97 
Total consolidated operations$9.19 $306.93 $86.82 $254.24 
Diluted earnings (loss) per share
Continuing operations$9.19 $(1.66)$86.82 $(50.73)
Discontinued operations 308.59  304.97 
Total consolidated operations$9.19 $306.93 $86.82 $254.24 
Dividends declared and paid per White Mountains’s
   common share
$ $ $1.00 $1.00 
See Notes to Consolidated Financial Statements.

5


WHITE MOUNTAINS INSURANCE GROUP, LTD.
CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY
(Unaudited)

 White Mountains’s Common Shareholders’ Equity 
MillionsCommon shares and paid-in surplusRetained earningsAOCI, after taxTotalNon-controlling interestTotal Equity
Balance at June 30, 2023$543.2 $3,380.7 $(1.7)$3,922.2 $203.7 $4,125.9 
Net income (loss) 23.6  23.6 (9.8)13.8 
Other comprehensive income (loss), net of tax  (1.0)(1.0)(.7)(1.7)
Total comprehensive income (loss) 23.6 (1.0)22.6 (10.5)12.1 
Dividends to noncontrolling interests    (.5)(.5)
Issuances of common shares      
Repurchases and retirements of common shares      
BAM member surplus contribution, net of tax    19.9 19.9 
Amortization of restricted share awards4.0   4.0  4.0 
Recognition of equity-based compensation expense
   of subsidiaries
.4   .4 .2 .6 
Net contributions and dilution from other
   noncontrolling interests
(.1)  (.1)2.3 2.2 
Balance at September 30, 2023$547.5 $3,404.3 $(2.7)$3,949.1 $215.1 $4,164.2 

 White Mountains’s Common Shareholders’ Equity 
MillionsCommon shares and paid-in surplusRetained earningsAOCI, after taxTotalNon-controlling interestTotal Equity
Balance at June 30, 2022$603.2 $2,725.1 $(5.0)$3,323.3 $168.7 $3,492.0 
Net income (loss)— 888.2 — 888.2 (18.7)869.5 
Other comprehensive income (loss), net of tax— — (1.8)(1.8).3 (1.5)
Other comprehensive income (loss) from discontinued
   operations, net of tax - NSM Group
— — .7 .7 — .7 
Net gain (loss) from foreign currency translation
   from sale of discontinued operations, net of tax -
   NSM Group
— — 2.9 2.9 — 2.9 
Total comprehensive income (loss)— 888.2 1.8 890.0 (18.4)871.6 
Dividends to noncontrolling interests— — — — (.5)(.5)
Repurchases and retirements of common shares(71.5)(437.4)— (508.9)— (508.9)
BAM member surplus contributions, net of tax— — — — 26.0 26.0 
Amortization of restricted share awards3.8 — — 3.8 — 3.8 
Recognition of equity-based compensation expense
   of subsidiaries
.4 — — .4 .2 .6 
Net contributions and dilution from other
   noncontrolling interests
(.6)— — (.6)(.2)(.8)
Disposition of noncontrolling interests— — — — (17.5)(17.5)
Balance at September 30, 2022$535.3 $3,175.9 $(3.2)$3,708.0 $158.3 $3,866.3 
See Notes to Consolidated Financial Statements.
6


CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (CONTINUED)
(Unaudited)

 White Mountains’s Common Shareholders’ Equity 
MillionsCommon shares and paid-in surplusRetained earningsAOCI, after taxTotalNon-controlling interestTotal Equity
Balance at January 1, 2023$538.6 $3,211.8 $(3.5)$3,746.9 $188.1 $3,935.0