What is White Mountains Insurance Group's casualty-active — 4?

White Mountains Insurance Group (WTM) reported casualty-active — 4 of 12.9% in Q4 2025.

How has White Mountains Insurance Group's casualty-active — 4 changed year-over-year?

White Mountains Insurance Group's casualty-active — 4 decreased by 10.4% year-over-year, from 14.4% to 12.9%.

What does casualty-active — 4 mean?

Tracks the historical claims development for the Casualty-Active segment, specifically focusing on adjustments to prior year loss provisions. Consistent positive development indicates conservative reserving practices, while negative development may signal under-reserving.

White Mountains Insurance Group (WTM) Casualty-Active — 4

Screener

Other product segments

Casualty-Runoff

14.8%0.0%

Marine & Energy

12.1%+51.2%

Specialty

8.7%+77.6%

Property and Accident & Health

6.4%0.0%

Similar metrics at other companies

HIPOCasualty Lines — 4

10%—

HGBermuda - Casualty — 4

15%-1.0pp

HGInternational - Casualty — 4

16%0.0pp

FRHCCivil Liability — 4

4%-17.3pp

FRHCLife Insurance — 4

204.9%+138pp

FRHCMotor Vehicle — 4

3%-1.2pp

Other financials

Income statement

See full

Revenue$844.6M+22.5%

Gross profit$764.5M+18.2%

Net income$199.5M+62.3%

Balance sheet

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Total debt$932.5M+34.2%

Total equity$5.4B+16.0%

Total assets$13.8B+16.4%

Cash flow

See full

Operating cash flow-$55.5M-131%

Valuation

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Market cap$5.3B+15.6%

P/E4.7×—

P/S1.4×-0.5×

Profitability

See full

Gross margin94.1%-3.2pp

Net margin29.3%—

Returns & leverage

See full

Return on equity22.4%—

Debt / equity0.2×0.0×

Where this comes from

Reported directly by White Mountains Insurance Group in its filing.

Tagged under the XBRL concept us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearFour.

The source filing: White Mountains Insurance Group’s 10-K, filed February 27, 2026.

Filed: Feb 27, 2026, 9:21 AM EST
Fiscal year: FY2025
Accession: 0001628280-26-012603

Casualty-Active	Casualty-Active / Average Annual Percentage Payout of Incurred Loss and LAE by Age, Net of Reinsurance	Casualty-Active / Average Annual Percentage Payout of Incurred Loss and LAE by Age, Net of Reinsurance	Casualty-Active / Average Annual Percentage Payout of Incurred Loss and LAE by Age, Net of Reinsurance	Casualty-Active / Average Annual Percentage Payout of Incurred Loss and LAE by Age, Net of Reinsurance	Average Annual Percentage Payout of Incurred Loss and LAE by Age, Net of Reinsurance	Average Annual Percentage Payout of Incurred Loss and LAE by Age, Net of Reinsurance	Average Annual Percentage Payout of Incurred Loss and LAE by Age, Net of Reinsurance	Average Annual Percentage Payout of Incurred Loss and LAE by Age, Net of Reinsurance	Average Annual Percentage Payout of Incurred Loss and LAE by Age, Net of Reinsurance	Average Annual Percentage Payout of Incurred Loss and LAE by Age, Net of Reinsurance
Years	1	2	3	4	5	6	7	8	9	10
	3.8%	7.5%	11.4%	12.9%	10.0%	11.2%	7.2%	5.1%	4.2%	3.4%

Item 16. Form 10-K Summary.

FAQ

What is White Mountains Insurance Group's casualty-active — 4?: White Mountains Insurance Group (WTM) reported casualty-active — 4 of 12.9% in Q4 2025.
How has White Mountains Insurance Group's casualty-active — 4 changed year-over-year?: White Mountains Insurance Group's casualty-active — 4 decreased by 10.4% year-over-year, from 14.4% to 12.9%.
What does casualty-active — 4 mean?: Tracks the historical claims development for the Casualty-Active segment, specifically focusing on adjustments to prior year loss provisions. Consistent positive development indicates conservative reserving practices, while negative development may signal under-reserving.