Debt (Tables)

9 Months Ended

Sep. 30, 2025

Debt Disclosure [Abstract]

Schedule of debt outstanding

The following table presents White Mountains’s debt outstanding as of September 30, 2025 and December 31, 2024:

$ in Millions	September 30, 2025		Effective   Rate (1)	December 31, 2024		Effective   Rate (1)
Ark 2021 Subordinated Notes Tranche 1	$	45.9		$	41.1
Ark 2021 Subordinated Notes Tranche 2	47.0			47.0
Ark 2021 Subordinated Notes Tranche 3	70.0			70.0
Unamortized issuance cost	(3.2)			(3.6)
Ark 2021 Subordinated Notes, carrying value	159.7		10.2%	154.5		11.8%
HG Global Senior Notes	150.0			150.0
Unamortized discount and issuance cost	(2.3)			(2.6)
HG Global Senior Notes, carrying value	147.7		10.9%	147.4		11.8%
Kudu Credit Facility	282.3			245.3
Unamortized issuance cost	(8.0)			(6.7)
Kudu Credit Facility, carrying value	274.3		9.0%	238.6		10.3%
Bamboo Credit Facility	109.5			—
Unamortized discount and issuance cost	(4.9)			—
Bamboo Credit Facility, carrying value	104.6		9.9%	—		N/A
Distinguished Credit Facility	139.8			—
Unamortized issuance cost	(1.7)			—
Distinguished Credit Facility, carrying value	138.1		11.3%	—		N/A
Distinguished other debt, carrying value	10.6		10.5%	—		N/A
Total Distinguished debt	148.7			—
Other Operations debt	35.9			22.4
Unamortized issuance cost	(.5)			(.4)
Other Operations debt, carrying value	35.4		8.5%	22.0		10.2%
Total debt	$	870.4		$	562.5

 (1) The effective rate for the nine months ended September 30, 2025 and the twelve months ended December 31, 2024 includes the effect of the amortization of debt issuance costs and original issue discount, but excludes the effect of the interest rate caps, where applicable. See Note 9 — “Derivatives.”

The following table presents the change in debt under the Kudu Credit Facility for the three and nine months ended September 30, 2025 and 2024:

	Three Months Ended September 30,				Nine Months Ended September 30,
Millions	2025		2024		2025		2024
Kudu Credit Facility
Beginning balance	$	253.3	$	210.3	$	245.3	$	210.3
Borrowings	29.0		15.0		37.0		15.0
Repayments	—		—		—		—
Ending balance	$	282.3	$	225.3	$	282.3	$	225.3

The following table presents the change in debt under the Bamboo Credit Facility for the three and nine months ended September 30, 2025:

Millions	Three Months Ended September 30, 2025		Nine Months Ended September 30, 2025
Bamboo Credit Facility
Beginning balance	$	109.7	$	—
Borrowings	—		110.0
Repayments	(.2)		(.5)
Ending balance	$	109.5	$	109.5

The following table presents the change in debt under the Distinguished Credit Facility for the period from September 2, 2025, the date of acquisition, through September 30, 2025:

Millions	September 2, 2025 - September 30, 2025
Distinguished Credit Facility
Beginning balance (1)	$	90.2
Borrowings (2)	50.0
Repayments	(.4)
Ending balance	$	139.8

(1) Represents the outstanding balance of the Distinguished Credit Facility assumed in the Distinguished Transaction. See Note 2 — “Significant Transactions.”

(2) Represents the $50.0 of incremental term loan drawn in connection with the closing of the Distinguished Transaction. See Note 2 — “Significant Transactions.”