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

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

EGCasualty Insurance — Year four

25.9%—

ACGLCasualty — Year Four

12.1%+0.2pp

WRBCasualty — Reserves for loss and loss adjustment expenses before 2016, net of reinsurance

$331.38M-7.4%

EGCasualty Insurance — Year five

24.9%—

RLICasualty — Shortduration Insurance Contracts Historical Claims Duration Year Four

18%+0.9pp

EGCasualty Insurance — 2025 Prior Year Development Excluding the Impact of ADC

$118.5M—

Other financials

Income statement

See full

Revenue$517.8M-10.4%

Gross profit$475.1M-16.7%

Net income-$27.2M-180%

Balance sheet

See full

Total debt$834.8M+23.5%

Total equity$5.4B+19.2%

Total assets$13.2B+19.7%

Cash flow

See full

Operating cash flow$30.5M+176%

Valuation

See full

Market cap$4.99B+9.8%

Profitability

See full

Gross margin94.9%-3.7pp

Net margin28.4%—

Returns & leverage

See full

Return on equity21.2%—

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 official record: White Mountains Insurance Group’s 10-K, filed February 27, 2026, on SEC EDGAR. View the filing →

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Questions, answered.

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.