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

12 Months Ended

Dec. 31, 2024

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, 2024

Millions	Cost		Carrying Value		Fair Value
Fixed maturity investments:
U.S. Government and agency obligations	$	461.8	$	462.1	$	462.1
Debt securities issued by corporations	1,444.5		1,414.2		1,414.2
Municipal obligations	3.2		3.2		3.2
Mortgage and asset-backed securities	400.2		373.9		373.9
Collateralized loan obligations	237.3		236.7		236.7
Foreign government and agency obligations	22.2		21.5		21.5
Total fixed maturity investments	2,569.2		2,511.6		2,511.6
Short-term investments	964.2		964.2		964.2
Investment in MediaAlpha (1)	59.2		201.6		201.6
Common equity securities:
Common equity securities - Industrial, Miscellaneous and Other	373.7		425.4		425.4
Common equity securities - Exchange traded funds	163.3		224.6		224.6
Total common equity securities	537.0		650.0		650.0
Other long-term investments (2)	1,748.7		2,150.2		2,150.2
Total investments	$	5,878.3	$	6,477.6	$	6,477.6

(1) Under GAAP, equity method eligible investments are considered related parties. White Mountains’s Investment in MediaAlpha is equity method eligible. See Note 17 — “Equity Method Eligible Investments.”

(2) Includes equity method eligible investments with a cost and carrying value of $1,083.8 and $1,423.3.