SCHEDULE IV - REINSURANCE

12 Months Ended

Dec. 31, 2025

SEC Schedule, 12-17, Insurance Companies, Reinsurance [Abstract]

SCHEDULE IV - REINSURANCE

WHITE MOUNTAINS INSURANCE GROUP, LTD.

REINSURANCE

Column A	Column B		Column C		Column D		Column E		Column F
$ in Millions Premiums Earned	Gross Amount		Ceded to Other Companies		Assumed from Other Companies		Net Amount		Percentage of Amount Assumed to Net
Year ended:
December 31, 2025
Ark/WM Outrigger	$	1,130.9	$	(632.4)	$	1,198.9	$	1,697.4	70.6	%
HG Global	—		—		30.8		30.8		100.0
Bamboo Captive (1)	—		(2.0)		28.7		26.7		107.5
Bamboo CRVs	—		—		22.2		22.2		100.0
December 31, 2024
Ark/WM Outrigger	1,004.2		(504.6)		1,088.2		1,587.8		68.5
HG Global	15.8		—		15.9		31.7		50.2
Bamboo Captive	—		(4.0)		43.4		39.4		110.2
Bamboo CRV	—		—		32.7		32.7		100.0
December 31, 2023
Ark/WM Outrigger	848.1		(364.0)		925.6		1,409.7		65.7
HG Global	28.7		—		2.5		31.2		8.0

(1) The Bamboo Captive’s results are from January 1, 2025 through December 5, 2025, the date of sale.

Schedules of the Registrant should be read in conjunction with the Consolidated Financial Statements and Notes.