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v3.25.1

Segment Information - Assets (Details) - USD ($) $ in Millions | Mar. 31, 2025 | Dec. 31, 2024
--- | --- | ---
Segment Reporting Information [Line Items] |  |
Total investments | $ 6,551.3 | $ 6,477.6
Total assets | 11,004.9 | 9,925.6
Total liabilities | 5,865.2 | 4,794.6
Total White Mountains’s common shareholders’ equity | 4,509.6 | 4,483.7
Noncontrolling interests | 630.1 | 647.3
Other Operations |  |
Segment Reporting Information [Line Items] |  |
Total investments | 1,447.2 | 1,570.4
Total assets | 1,638.0 | 1,754.2
Total liabilities | 130.5 | 181.3
Total White Mountains’s common shareholders’ equity | 1,498.4 | 1,563.8
Noncontrolling interests | 9.1 | 9.1
P&C Insurance and Reinsurance (Ark/WM Outrigger) | Operating Segments |  |
Segment Reporting Information [Line Items] |  |
Total investments | 3,215.0 | 3,139.7
Total assets | 6,325.5 | 5,299.0
Total liabilities | 4,658.1 | 3,664.8
Total White Mountains’s common shareholders’ equity | 1,251.4 | 1,223.8
Noncontrolling interests | 416.0 | 410.4
Financial Guarantee (HG Global) | Operating Segments |  |
Segment Reporting Information [Line Items] |  |
Total investments | 686.0 | 667.6
Total assets | 1,203.1 | 1,179.4
Total liabilities | 463.3 | 464.1
Total White Mountains’s common shareholders’ equity | 752.3 | 728.7
Noncontrolling interests | (12.5) | (13.4)
Dividends payable | 478.0 | 462.1
Asset Management (Kudu) | Operating Segments |  |
Segment Reporting Information [Line Items] |  |
Total investments | 1,138.1 | 1,041.9
Total assets | 1,223.3 | 1,108.4
Total liabilities | 330.6 | 316.7
Total White Mountains’s common shareholders’ equity | 766.3 | 664.1
Noncontrolling interests | 126.4 | 127.6
Bamboo | Operating Segments |  |
Segment Reporting Information [Line Items] |  |
Total investments | 65.0 | 58.0
Total assets | 615.0 | 584.6
Total liabilities | 282.7 | 167.7
Total White Mountains’s common shareholders’ equity | 241.2 | 303.3
Noncontrolling interests | $ 91.1 | $ 113.6

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