SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES

12 Months Ended

Dec. 31, 2023

SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Abstract]

SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES

WHITE MOUNTAINS INSURANCE GROUP, LTD.

SUMMARY OF INVESTMENTS—OTHER THAN

INVESTMENTS IN RELATED PARTIES

As of December 31, 2023

Millions	Cost		Carrying Value		Fair Value
Fixed maturity investments:
U.S. Government and agency obligations	$	209.0	$	204.9	$	204.9
Debt securities issued by corporations	1,085.9		1,045.0		1,045.0
Municipal obligations	275.1		260.9		260.9
Mortgage and asset-backed securities	417.2		389.4		389.4
Collateralized loan obligations	211.2		209.1		209.1
Total fixed maturity investments	2,198.4		2,109.3		2,109.3
Short-term investments	1,487.0		1,487.9		1,487.9
Investment in MediaAlpha	59.2		254.9		254.9
Common equity securities:
Common equity securities - Industrial, Miscellaneous, and Other	370.2		400.6		400.6
Common equity securities - Exchange traded funds	113.3		137.8		137.8
Total common equity securities	483.5		538.4		538.4
Other long-term investments	1,655.7		1,998.2		1,998.2
Total investments	$	5,883.8	$	6,388.7	$	6,388.7