v3.26.3
CONSOLIDATED BALANCE SHEETS - USD ($)
Sep. 30, 2026
Dec. 31, 2025
Assets    
Common equity securities, at fair value $ 549,000,000.0 $ 483,000,000.0
Other long-term investments 3,417,500,000 2,958,500,000
Total investments 8,280,900,000 8,323,900,000
Goodwill and other intangible assets 1,169,400,000 1,020,200,000
Total assets 13,362,600,000 12,306,500,000
Liabilities    
Debt 928,600,000 837,000,000.0
Total liabilities 7,136,300,000 6,051,400,000
Redeemable noncontrolling interests 131,500,000 131,500,000
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 2,386,823 and 2,479,677 shares 2,400,000 2,500,000
Paid-in surplus 572,300,000 576,500,000
Retained earnings 4,777,100,000 4,845,600,000
Accumulated other comprehensive income (loss), after-tax:    
Net unrealized gains (losses) from foreign currency translation 1,300,000 800,000
Total White Mountains’s common shareholders’ equity 5,353,100,000 5,425,400,000
Nonredeemable noncontrolling interests 741,700,000 698,200,000
Total equity 6,094,800,000 6,123,600,000
Total liabilities, redeemable noncontrolling interests and equity 13,362,600,000 12,306,500,000
Other Operations    
Assets    
Fixed maturity investments, at fair value 361,800,000 159,200,000
Common equity securities, at fair value 204,000,000.0 30,700,000
Investment in MediaAlpha, at fair value 170,900,000 231,200,000
Short-term investments, at fair value 236,800,000 806,900,000
Other long-term investments 1,230,400,000 977,400,000
Total investments 2,203,900,000 2,205,400,000
Cash 21,200,000 38,400,000
Goodwill and other intangible assets 47,900,000 50,800,000
Other assets 91,100,000 95,900,000
Total assets 2,369,000,000 2,395,500,000
Liabilities    
Debt 17,300,000 18,900,000
Accrued incentive compensation 55,400,000 100,100,000
Other liabilities 49,000,000.0 55,400,000
Total liabilities 125,400,000 178,000,000.0
Redeemable noncontrolling interests 0 0
Accumulated other comprehensive income (loss), after-tax:    
Total White Mountains’s common shareholders’ equity 2,238,900,000 2,212,000,000
Nonredeemable noncontrolling interests 4,700,000 5,500,000
Other Operations | Other Disposal Group    
Assets    
Total investments 1,500,000 1,000,000.0
Assets held for sale - Other 4,900,000 5,000,000.0
Liabilities    
Liabilities held for sale - Other 3,700,000 3,600,000
P&C Insurance and Reinsurance (Ark/WM Outrigger)    
Liabilities    
Loss and loss adjustment expense reserves 2,747,400,000 2,481,000,000
P&C Insurance and Reinsurance (Ark/WM Outrigger) | Operating Segments    
Assets    
Fixed maturity investments, at fair value 1,971,400,000 1,917,900,000
Common equity securities, at fair value 345,000,000.0 452,300,000
Short-term investments, at fair value 633,100,000 866,600,000
Other long-term investments 868,000,000.0 689,700,000
Total investments 3,817,500,000 3,926,500,000
Cash 129,700,000 104,800,000
Reinsurance recoverables 1,076,100,000 836,100,000
Insurance premiums receivable 1,222,100,000 848,400,000
Deferred acquisition costs 264,800,000 211,100,000
Goodwill and other intangible assets 292,500,000 292,500,000
Other assets 344,600,000 134,700,000
Total assets 7,147,300,000 6,354,100,000
Liabilities    
Loss and loss adjustment expense reserves 2,747,400,000 2,481,000,000
Unearned insurance premiums 1,427,400,000 1,026,100,000
Debt 159,000,000.0 159,700,000
Reinsurance payable 492,300,000 286,200,000
Contingent consideration 400,000,000.0 328,300,000
Other liabilities 233,700,000 247,200,000
Total liabilities 5,459,800,000 4,528,500,000
Redeemable noncontrolling interests 0 0
Accumulated other comprehensive income (loss), after-tax:    
Total White Mountains’s common shareholders’ equity 1,197,600,000 1,360,400,000
Nonredeemable noncontrolling interests 489,900,000 465,200,000
Asset Management (Kudu) | Operating Segments    
Assets    
Short-term investments, at fair value 120,900,000 21,900,000
Other long-term investments 1,319,100,000 1,291,400,000
Total investments 1,440,000,000 1,313,300,000
Cash 1,000,000.0 34,500,000
Accrued investment income 22,000,000.0 25,300,000
Goodwill and other intangible assets 7,600,000 7,700,000
Other assets 7,600,000 21,500,000
Total assets 1,478,200,000 1,402,300,000
Liabilities    
Debt 350,900,000 350,400,000
Other liabilities 122,600,000 96,500,000
Total liabilities 473,500,000 446,900,000
Redeemable noncontrolling interests 0 0
Accumulated other comprehensive income (loss), after-tax:    
Total White Mountains’s common shareholders’ equity 863,900,000 814,200,000
Nonredeemable noncontrolling interests 140,800,000 141,200,000
HG Global | Operating Segments    
Assets    
Fixed maturity investments, at fair value 707,600,000 693,400,000
Short-term investments, at fair value 40,700,000 90,800,000
Total investments 748,300,000 784,200,000
Cash 600,000 100,000
BAM Surplus Notes, at fair value 335,500,000 339,000,000.0
Insurance premiums receivable 13,600,000 11,400,000
Deferred acquisition costs 102,000,000.0 96,900,000
Other assets 5,700,000 5,200,000
Total assets 1,205,700,000 1,236,800,000
Liabilities    
Loss and loss adjustment expense reserves 0 0
Unearned insurance premiums 342,500,000 327,900,000
Debt 197,400,000 147,800,000
Other liabilities 26,700,000 23,800,000
Total liabilities 566,600,000 499,500,000
Redeemable noncontrolling interests 0 0
Accumulated other comprehensive income (loss), after-tax:    
Total White Mountains’s common shareholders’ equity 664,200,000 755,700,000
Nonredeemable noncontrolling interests (25,100,000) (18,400,000)
Specialty Insurance Distribution (Distinguished) | Operating Segments    
Assets    
Short-term investments, at fair value 70,600,000 94,000,000.0
Total investments 70,600,000 94,000,000.0
Cash 4,300,000 2,700,000
Premiums, commissions and fees receivable 52,200,000 45,700,000
Goodwill and other intangible assets 558,700,000 577,700,000
Other assets 35,100,000 15,300,000
Total assets 720,900,000 735,400,000
Liabilities    
Debt 140,900,000 140,800,000
Premiums and commissions payable 87,900,000 81,300,000
Other liabilities 88,600,000 85,000,000.0
Total liabilities 317,400,000 307,100,000
Redeemable noncontrolling interests 131,500,000 131,500,000
Accumulated other comprehensive income (loss), after-tax:    
Total White Mountains’s common shareholders’ equity 196,000,000.0 223,100,000
Nonredeemable noncontrolling interests 76,000,000.0 73,700,000
Services, Industrial and Consumer (WTM Partners) | Operating Segments    
Assets    
Short-term investments, at fair value 600,000 500,000
Total investments 600,000 500,000
Cash 10,200,000 4,400,000
Accounts receivable 88,700,000 39,500,000
Contract assets 37,100,000 17,800,000
Goodwill and other intangible assets 262,700,000 91,500,000
Other assets 42,200,000 28,700,000
Total assets 441,500,000 182,400,000
Liabilities    
Debt 63,100,000 19,400,000
Contract liabilities 43,200,000 24,800,000
Other liabilities 87,300,000 47,200,000
Total liabilities 193,600,000 91,400,000
Redeemable noncontrolling interests 0 0
Accumulated other comprehensive income (loss), after-tax:    
Total White Mountains’s common shareholders’ equity 192,500,000 60,000,000.0
Nonredeemable noncontrolling interests $ 55,400,000 $ 31,000,000.0