What is White Mountains Insurance Group's casualty-active — 9?

White Mountains Insurance Group (WTM) reported casualty-active — 9 of 4.2% in Q4 2025.

How has White Mountains Insurance Group's casualty-active — 9 changed year-over-year?

White Mountains Insurance Group's casualty-active — 9 increased by 13.5% year-over-year, from 3.7% to 4.2%.

What does casualty-active — 9 mean?

Represents the cumulative adjustment to prior period loss reserves for the Casualty-Active segment. It serves as a performance indicator for the segment's historical underwriting discipline and reserve management strategy.

White Mountains Insurance Group (WTM) Casualty-Active — 9

Screener

Other product segments

Casualty-Runoff

3.2%+3.2%

Specialty

1.2%-7.7%

Property and Accident & Health

0.2%+100%

Marine & Energy

0.1%-66.7%

Similar metrics at other companies

HGBermuda - Casualty — 9

4%—

HGInternational - Casualty — 9

0%—

FRHCCivil Liability — 9

0%—

FRHCLife Insurance — 9

0%—

FRHCMotor Vehicle — 9

0%—

FRHCProperty Damage — 9

0%—

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:ShortdurationInsuranceContractsHistoricalClaimsDurationYearNine.

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 — 9?: White Mountains Insurance Group (WTM) reported casualty-active — 9 of 4.2% in Q4 2025.
How has White Mountains Insurance Group's casualty-active — 9 changed year-over-year?: White Mountains Insurance Group's casualty-active — 9 increased by 13.5% year-over-year, from 3.7% to 4.2%.
What does casualty-active — 9 mean?: Represents the cumulative adjustment to prior period loss reserves for the Casualty-Active segment. It serves as a performance indicator for the segment's historical underwriting discipline and reserve management strategy.