Third-Party Reinsurance (Tables)

9 Months Ended

Sep. 30, 2024

Reinsurance Disclosures [Abstract]

Effects of reinsurance

The following table summarizes the effects of reinsurance on written and earned premiums and on loss and LAE for the Ark/WM Outrigger segment for the three and nine months ended September 30, 2024 and 2023:

Millions	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Written premiums:
Direct	$	239.0	$	189.4	$	863.4	$	727.1
Assumed	134.6		61.8		1,079.3		939.6
Gross written premiums	373.6		251.2		1,942.7		1,666.7
Ceded (1)	(34.2)		(20.2)		(502.5)		(360.3)
Net written premiums	$	339.4	$	231.0	$	1,440.2	$	1,306.4
Earned premiums:
Direct	$	317.6	$	273.1	$	731.5	$	624.1
Assumed	432.6		370.0		805.3		684.6
Gross earned premiums	750.2		643.1		1,536.8		1,308.7
Ceded (2)	(198.0)		(144.2)		(363.5)		(261.4)
Net earned premiums	$	552.2	$	498.9	$	1,173.3	$	1,047.3
Loss and loss adjustment expenses:
Gross	$	350.7	$	269.3	$	852.7	$	627.5
Ceded (3)	(62.4)		(3.5)		(208.7)		(46.4)
Net loss and loss adjustment expenses	$	288.3	$	265.8	$	644.0	$	581.1

(1) The three months ended September 30, 2024 and 2023 exclude $8.8 and $6.0, and the nine months ended September 30, 2024 and 2023 exclude $82.0 and $108.4 ceded by Ark to WM Outrigger Re, which eliminate in White Mountains’s consolidated financial statements.

(2) The three months ended September 30, 2024 and 2023 exclude $45.0 and $60.6, and the nine months ended September 30, 2024 and 2023 exclude $62.8 and $75.4, ceded by Ark to WM Outrigger Re, which eliminate in White Mountains’s consolidated financial statements.

(3) The three months ended September 30, 2024 and 2023 exclude $13.2 and $7.3, and the nine months ended September 30, 2024 and 2023 exclude $13.6 and $7.9, ceded by Ark to WM Outrigger Re, which eliminate in White Mountains’s consolidated financial statements.

The following table presents the Ark/WM Outrigger segment’s reinsurance recoverables as of September 30, 2024 and December 31, 2023:

Millions	September 30, 2024		December 31, 2023
Reinsurance recoverables on unpaid losses (1)	$	507.2	$	340.8
Reinsurance recoverables on paid losses	27.9		27.4
Ceded unearned premiums (2)	212.9		73.8
Reinsurance recoverables	$	748.0	$	442.0

(1) The reinsurance recoverables on unpaid losses exclude $28.0 and $15.6 ceded by Ark to WM Outrigger Re as of September 30, 2024 and December 31, 2023, which eliminate in White Mountains’s consolidated financial statements.

(2) The ceded unearned premiums exclude $25.0 and $5.7 ceded by Ark to WM Outrigger Re as of September 30, 2024 and December 31, 2023,

which eliminate in White Mountains’s consolidated financial statements.

The following tables present schedules of written premiums and earned premiums included in the HG Global segment for the three and nine months ended September 30, 2024 and 2023:

	Three Months Ended September 30, 2024
Millions	HG Global
Written premiums:
Direct	$	—
Assumed	14.0
Gross written premiums (1)	$	14.0
Earned premiums:
Direct	$	—
Assumed	7.5
Gross earned premiums (1)	$	7.5

(1) There are no ceded premium amounts in the periods presented, such that gross written premiums and gross earned premiums are equivalent to net written premiums and net earned premiums, respectively.

	Three Months Ended September 30, 2023
Millions	HG Global		BAM		Eliminations		Total
Written premiums:
Direct	$	—	$	16.5	$	—	$	16.5
Assumed	14.2		—		(14.2)		—
Gross written premiums (1)	$	14.2	$	16.5	$	(14.2)	$	16.5
Earned premiums:
Direct	$	—	$	7.4	$	—	$	7.4
Assumed	6.6		.5		(6.6)		.5
Gross earned premiums (1)	$	6.6	$	7.9	$	(6.6)	$	7.9

(1) There are no ceded premium amounts in the periods presented, such that gross written premiums and gross earned premiums are equivalent to net written premiums and net earned premiums, respectively.

	Nine Months Ended September 30, 2024
Millions	HG Global		BAM		Eliminations		Total
Written premiums:
Direct	$	—	$	24.1	$	—	$	24.1
Assumed	34.5		—		(20.5)		14.0
Gross written premiums (1)	$	34.5	$	24.1	$	(20.5)	$	38.1
Earned premiums:
Direct	$	—	$	15.8	$	—	$	15.8
Assumed	21.5		1.0		(14.0)		8.5
Gross earned premiums (1)	$	21.5	$	16.8	$	(14.0)	$	24.3

(1) There are no ceded premium amounts in the periods presented, such that gross written premiums and gross earned premiums are equivalent to net written premiums and net earned premiums, respectively.

	Nine Months Ended September 30, 2023
Millions	HG Global		BAM		Eliminations		Total
Written premiums:
Direct	$	—	$	37.3	$	—	$	37.3
Assumed	31.9		—		(31.9)		—
Gross written premiums (1)	$	31.9	$	37.3	$	(31.9)	$	37.3
Earned premiums:
Direct	$	—	$	21.4	$	—	$	21.4
Assumed	19.4		1.9		(19.4)		1.9
Gross earned premiums (1)	$	19.4	$	23.3	$	(19.4)	$	23.3

(1) There are no ceded premium amounts in the periods presented, such that gross written premiums and gross earned premiums are equivalent to net written premiums and net earned premiums, respectively.

Gross and net reinsurance recoverables by reinsurers ratings

The following table presents the Ark/WM Outrigger segment’s gross and net reinsurance recoverables by the reinsurer’s A.M. Best Company, Inc (“A.M. Best”) ratings as of September 30, 2024:

$ in Millions	As of September 30, 2024
A.M. Best Rating(1)	Gross			Collateral			Net		% of Total
A+ or better	$	358.1		$	—		$	358.1	78.9	%
A- to A	84.2			—			84.2		18.5
B++ or lower and not rated	92.8		(2)	81.1		(2)	11.7		2.6
Total	$	535.1		$	81.1		$	454.0	100.0	%

(1) A.M. Best financial strength ratings as detailed above are: “A+ or better” (Superior) “A- to A” (Excellent), “B++” (Good).

(2) Excludes $28.0 ceded by Ark to WM Outrigger Re as of September 30, 2024, which eliminates in White Mountains’s consolidated financial statements.