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Investment Securities (Tables)

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Schedule of pre-tax net investment income

The following table presents pre-tax net investment income for the years ended December 31, 2023, 2022 and 2021:

						Year Ended December 31,
Millions						2023						2022						2021
Fixed maturity investments						$	64.4					$	41.4					$	28.8
Short-term investments						52.0						16.4						.6
Common equity securities						4.1						1.6						.1
Other long-term investments						76.1						68.1						56.3
Amount attributable to TPC Providers						—						(1.0)						(1.0)
Total investment income						196.6						126.5						84.8
Third-party investment expenses						(2.4)						(2.1)						(2.3)
Net investment income, pre-tax						$	194.2					$	124.4					$	82.5

Schedule of net realized and unrealized investment gains and losses

The following table presents net realized and unrealized investment gains (losses) for the years ended December 31, 2023, 2022 and 2021:

						Year Ended December 31,
Millions						2023						2022						2021
Realized investment gains (losses)
Fixed maturity investments						$	(4.7)					$	(11.9)					$	3.9
Short-term investments						(.2)						(1.4)						(.1)
Common equity securities						29.5						—						.4
Investment in MediaAlpha						—						—						160.3
Other long-term investments						72.2						128.4						(7.7)
Net realized investment gains (losses)						96.8						115.1						156.8
Unrealized investment gains (losses)
Fixed maturity investments						66.1						(168.4)						(42.2)
Short-term investments						1.9						(1.1)						—
Common equity securities						47.1						(7.1)						14.9
Investment in MediaAlpha						27.1						(93.0)						(540.6)
Other long-term investments						195.2						(43.8)						172.7
Net unrealized investment gains (losses)						337.4						(313.4)						(395.2)
Net realized and unrealized investment gains (losses), before    amount attributable to TPC providers (1)						434.2						(198.3)						(238.4)
Amount attributable to TPC Providers						—						6.8						(7.7)
Net realized and unrealized investment gains (losses)						$	434.2					$	(191.5)					$	(246.1)
Fixed maturity and short-term investments
Net realized and unrealized investment gains (losses)						$	63.1					$	(182.8)					$	(38.4)
Less: net realized and unrealized gains (losses) on investment    securities sold during the period						4.7						(2.9)						(8.4)
Net unrealized investment gains (losses) recognized during the    period on investment securities held at the end of the period						$	58.4					$	(179.9)					$	(30.0)
Common equity securities and investment in MediaAlpha
Net realized and unrealized investment gains (losses) on    common equity securities						$	76.6					$	(7.1)					$	15.3
Net realized and unrealized investment gains (losses) from    investment in MediaAlpha						27.1						(93.0)						(380.3)
Total net realized and unrealized investment gains (losses)						103.7						(100.1)						(365.0)
Less: net realized and unrealized gains (losses) on investment    securities sold during the period						28.4						—						20.3
Net unrealized investment gains (losses) recognized during the    period on investment securities held at the end of the period						$	75.3					$	(100.1)					$	(385.3)

(1) For 2023, 2022 and 2021, includes $13.6, $(29.3) and $(7.7) of net realized and unrealized investment gains (losses) related to foreign currency exchange.

The following table presents total net unrealized gains (losses) attributable to Level 3 investments for the years ended December 31, 2023, 2022 and 2021 for investments still held at the end of the period:

						Year Ended December 31,
Millions						2023						2022						2021
Total net unrealized investment gains on other long-term investments held at    the end of period, pre-tax						$	133.9					$	56.5					$	98.9

Schedule of equity securities and other long-term investments

The following tables present the cost or amortized cost, gross unrealized investment gains (losses), net foreign currency gains (losses) and carrying value of White Mountains’s fixed maturity investments as of December 31, 2023 and 2022:

						December 31, 2023
Millions						Cost or Amortized Cost						Gross Unrealized Gains						Gross Unrealized Losses						Net Foreign Currency Gains (Losses)						Carrying Value
U.S. Government and agency obligations						$	209.0					$	.3					$	(4.4)					$	—					$	204.9
Debt securities issued by corporations						1,085.9						5.6						(45.4)						(1.1)						1,045.0
Municipal obligations						275.1						.9						(15.1)						—						260.9
Mortgage and asset-backed securities						417.2						2.0						(29.8)						—						389.4
Collateralized loan obligations						211.2						.4						(2.4)						(.1)						209.1
Total fixed maturity investments						$	2,198.4					$	9.2					$	(97.1)					$	(1.2)					$	2,109.3

						December 31, 2022
Millions						Cost or Amortized Cost						Gross Unrealized Gains						Gross Unrealized Losses												Net Foreign Currency Gains (Losses)						Carrying Value
U.S. Government and agency obligations						$	216.6					$	—					$	(10.2)											$	—					$	206.4
Debt securities issued by corporations						1,098.3						.6						(78.3)												(1.8)						1,018.8
Municipal obligations						281.6						.4						(23.4)												—						258.6
Mortgage and asset-backed securities						288.7						—						(34.5)												—						254.2
Collateralized loan obligations						190.8						.1						(6.0)												(2.0)						182.9
Total fixed maturity investments						$	2,076.0					$	1.1					$	(152.4)											$	(3.8)					$	1,920.9

The following tables present the cost or amortized cost, gross unrealized investment gains (losses), net foreign currency gains (losses) and carrying value of common equity securities, White Mountains’s investment in MediaAlpha and other long-term investments as of December 31, 2023 and 2022:

						December 31, 2023
Millions						Cost or Amortized Cost						Gross Unrealized Gains						Gross Unrealized Losses						Net Foreign Currency Gains (Losses)						Carrying Value
Common equity securities						$	483.5					$	62.3					$	(1.2)					$	(6.2)					$	538.4
Investment in MediaAlpha						$	59.2					$	195.7					$	—					$	—					$	254.9
Other long-term investments						$	1,655.7					$	446.3					$	(94.5)					$	(9.3)					$	1,998.2

						December 31, 2022
Millions						Cost or Amortized Cost						Gross Unrealized Gains						Gross Unrealized Losses						Net Foreign Currency Gains (Losses)						Carrying Value
Common equity securities						$	660.6					$	26.7					$	(8.4)					$	(10.5)					$	668.4
Investment in MediaAlpha						$	—					$	168.6					$	—					$	—					$	168.6
Other long-term investments						$	1,340.8					$	271.1					$	(107.1)					$	(16.8)					$	1,488.0

Schedule of contractual maturities of fixed maturities

The following table presents the cost or amortized cost and carrying value of White Mountains’s fixed maturity investments by contractual maturity as of December 31, 2023. Actual maturities could differ from contractual maturities because borrowers may have the right to call or prepay certain obligations with or without call or prepayment penalties.

						December 31, 2023
Millions						Cost or Amortized Cost						Carrying Value
Due in one year or less						$	319.9					$	315.0
Due after one year through five years						845.0						813.9
Due after five years through ten years						303.4						287.0
Due after ten years						101.7						94.9
Mortgage and asset-backed securities and    collateralized loan obligations						628.4						598.5
Total fixed maturity investments						$	2,198.4					$	2,109.3

Schedule of fair value measurements for investment securities by level

The following tables present White Mountains’s fair value measurements for investments as of December 31, 2023 and 2022 by level. See Note 1 — “Basis of Presentation and Significant Accounting Policies”. The major security types were based on the legal form of the securities. White Mountains has disaggregated its fixed maturity investments based on the issuing entity type, which impacts credit quality, with debt securities issued by U.S. government entities carrying minimal credit risk, while the credit and other risks associated with other issuers, such as corporations, municipalities or entities issuing mortgage and asset-backed securities vary depending on the nature of the issuing entity type. White Mountains further disaggregates debt securities issued by corporations by industry sector because investors often reference commonly used benchmarks and their subsectors to monitor risk and performance. Accordingly, White Mountains has further disaggregated this asset class into subclasses based on the similar sectors and industry classifications it uses to evaluate investment risk and performance against commonly used benchmarks, such as the Bloomberg Barclays U.S. Intermediate Aggregate.

						December 31, 2023
Millions						Fair Value						Level 1						Level 2						Level 3
Fixed maturity investments:
U.S. Government and agency obligations						$	204.9					$	204.9					$	—					$	—
Debt securities issued by corporations:
Financials						309.8						—						309.8						—
Consumer						214.6						—						214.6						—
Industrial						121.6						—						121.6						—
Healthcare						121.3						—						121.3						—
Technology						108.9						—						108.9						—
Utilities						70.2						—						70.2						—
Communications						46.3						—						46.3						—
Energy						28.9						—						28.9						—
Materials						23.4						—						23.4						—
Total debt securities issued by corporations						1,045.0						—						1,045.0						—
Municipal obligations						260.9						—						260.9						—
Mortgage and asset-backed securities						389.4						—						389.4						—
Collateralized loan obligations						209.1						—						209.1						—
Total fixed maturity investments						2,109.3						204.9						1,904.4						—
Short-term investments						1,487.9						1,457.6						30.3						—
Common equity securities:
Exchange-traded funds						137.8						137.8						—						—
Other (1)						400.6						—						400.6						—
Total common equity securities						538.4						137.8						400.6						—
Investment in MediaAlpha						254.9						254.9						—						—
Other long-term investments						1,164.4						—						26.2						1,138.2
Other long-term investments — NAV (2)						833.8						—						—						—
Total other long-term investments						1,998.2						—						26.2						1,138.2
Total investments						$	6,388.7					$	2,055.2					$	2,361.5					$	1,138.2

(1) Consists of investments in listed funds that predominantly invest in international equities.

(2) Consists of private equity funds and hedge funds, a bank loan fund, Lloyd’s trust deposits and ILS funds for which fair value is measured using NAV as a practical expedient. Investments for which fair value is measured at NAV are not classified within the fair value hierarchy.

						December 31, 2022
Millions						Fair Value						Level 1						Level 2						Level 3
Fixed maturity investments:
U.S. Government and agency obligations						$	206.4					$	206.4					$	—					$	—
Debt securities issued by corporations:
Financials						291.2						—						291.2						—
Consumer						191.9						—						191.9						—
Industrial						115.4						—						115.4						—
Healthcare						121.3						—						121.3						—
Technology						123.7						—						123.7						—
Utilities						73.8						—						73.8						—
Communications						47.9						—						47.9						—
Energy						33.9						—						33.9						—
Materials						19.7						—						19.7						—
Total debt securities issued by corporations						1,018.8						—						1,018.8						—
Municipal obligations						258.6						—						258.6						—
Mortgage and asset-backed securities						254.2						—						254.2						—
Collateralized loan obligations						182.9						—						182.9						—
Total fixed maturity investments						1,920.9						206.4						1,714.5						—
Short-term investments						924.1						924.1						—						—
Common equity securities:
Exchange-traded funds						333.8						333.8						—						—
Other (1)						334.6						—						334.6						—
Total common equity securities						668.4						333.8						334.6						—
Investment in MediaAlpha						168.6						168.6						—						—
Other long-term investments						926.4						—						14.8						911.6
Other long-term investments — NAV (2)						561.6						—						—						—
Total other long-term investments						1,488.0						—						14.8						911.6
Total investments						$	5,170.0					$	1,632.9					$	2,063.9					$	911.6

(1) Consists of investments in listed funds that predominantly invest in international equities.

(2) Consists of private equity funds and hedge funds, a bank loan fund, Lloyd’s trust deposits and ILS funds for which fair value is measured using NAV as a practical expedient. Investments for which fair value is measured at NAV are not classified within the fair value hierarchy.

Schedule of credit ratings of debt securities issued

The following table presents the credit ratings of debt securities issued by corporations held in White Mountains’s investment portfolio as of December 31, 2023 and 2022:

						Fair Value as of December 31,
Millions						2023						2022
AAA						$	11.5					$	11.3
AA						83.8						96.0
A						552.4						567.9
BBB						390.9						337.7
Other						6.4						5.9
Debt securities issued by corporations (1)						$	1,045.0					$	1,018.8

(1)    Credit ratings are based upon issuer credit ratings provided by Standard & Poor’s Financial Services LLC (“Standard & Poor’s”), or if unrated by Standard & Poor’s, long-term obligation ratings provided by Moody’s Investor Service, Inc.

Schedule of mortgage and asset-backed securities

The following table presents the fair value of White Mountains’s mortgage and asset-backed securities and collateralized loan obligations as of December 31, 2023 and 2022:

						December 31, 2023																		December 31, 2022
Millions						Fair Value						Level 2						Level 3						Fair Value						Level 2						Level 3
Mortgage-backed securities:
Agency:
FNMA						$	198.8					$	198.8					$	—					$	124.5					$	124.5					$	—
FHLMC						137.2						137.2						—						78.8						78.8						—
GNMA						30.2						30.2						—						28.3						28.3						—
Total agency (1)						366.2						366.2						—						231.6						231.6						—
Non-agency: Residential						.2						.2						—						.3						.3						—
Total non-agency						.2						.2						—						.3						.3						—
Total mortgage-backed securities						366.4						366.4						—						231.9						231.9						—
Other asset-backed securities:
Credit card receivables						3.3						3.3						—						11.9						11.9						—
Vehicle receivables						17.2						17.2						—						10.4						10.4						—
Other						2.5						2.5						—						—						—						—
Total other asset-backed securities						23.0						23.0						—						22.3						22.3						—
Total mortgage and asset-backed securities						389.4						389.4						—						254.2						254.2						—
Collateralized loan obligations:						209.1						209.1						—						182.9						182.9						—
Total mortgage and asset-backed securities and    collateralized loan obligations						$	598.5					$	598.5					$	—					$	437.1					$	437.1					$	—

(1) Represents publicly traded mortgage-backed securities which carry the full faith and credit guaranty of the U.S. Government (i.e., GNMA) or are guaranteed by a government sponsored entity (i.e., FNMA, FHLMC).

Schedule of carrying values for other long-term investments

						Fair Value as of December 31, 2023
Millions						Ark/WM Outrigger						Kudu						Other						Total
Kudu’s Participation Contracts						$	—					$	890.5					$	—					$	890.5
PassportCard/DavidShield						—						—						150.0						150.0
Elementum Holdings, L.P.						—						—						35.0						35.0
Other unconsolidated entities (1)						—						—						48.1						48.1
Total unconsolidated entities						—						890.5						233.1						1,123.6
Private equity funds and hedge funds						55.5						—						257.4						312.9
Bank loan fund						194.4						—						—						194.4
ILS funds						—						—						160.5						160.5
Lloyd’s trust deposits						158.0						—						—						158.0
Private debt instruments						—						—						10.0						10.0
Other						33.0						5.8						—						38.8
Total other long-term investments						$	440.9					$	896.3					$	661.0					$	1,998.2

(1) Includes White Mountains’s noncontrolling equity interests in certain preferred securities, private common equity securities, limited liability company units and Simple Agreement for Future Equity (“SAFE”) investments.

						Fair Value as of December 31, 2022
Millions						Ark/WM Outrigger						Kudu						Other						Total
Kudu’s Participation Contracts						$	—					$	695.9					$	—					$	695.9
PassportCard/DavidShield						—						—						135.0						135.0
Elementum Holdings, L.P.						—						—						30.0						30.0
Other unconsolidated entities (1)						—						—						37.2						37.2
Total unconsolidated entities						—						695.9						202.2						898.1
Private equity funds and hedge funds						40.4						—						157.4						197.8
Bank loan fund						174.8						—						—						174.8
ILS funds						—						—						49.3						49.3
Lloyd’s trust deposits						137.4						—						—						137.4
Private debt instruments						—						—						9.6						9.6
Other						21.0						—						—						21.0
Total other long-term investments						$	373.6					$	695.9					$	418.5					$	1,488.0

(1) Includes White Mountains’s noncontrolling equity interests in certain preferred securities, private common equity securities, limited liability company units and SAFE.

Schedule of investments and unfunded commitments by investment objective and sector

The following table presents the fair value of investments and unfunded commitments in private equity funds and hedge funds by investment objective and sector as of December 31, 2023 and 2022:

						December 31, 2023												December 31, 2022
Millions						Fair Value						Unfunded Commitments						Fair Value						Unfunded Commitments
Private equity funds
Aerospace/Defense/Government						$	157.2					$	17.4					$	59.4					$	37.5
Financial services						87.5						37.8						77.1						54.3
Real estate						3.9						2.5						4.1						2.5
Total private equity funds						248.6						57.7						140.6						94.3
Hedge funds
Long/short equity financials and business services						54.4						—						49.0						—
European small/mid cap						9.9						—						8.2						—
Total hedge funds						64.3						—						57.2						—
Total private equity funds and hedge funds    included in other long-term investments						$	312.9					$	57.7					$	197.8					$	94.3

Schedule investments in private equity funds subject to lock-up periods

The following table presents investments in private equity funds that were subject to lock-up periods as of December 31, 2023:

Millions						1 – 3 years						3 – 5 years						5 – 10 years						>10 years						Total
Private equity funds — expected lock-up period remaining						$	4.5					$	71.0					$	155.4					$	17.7					$	248.6

Schedule of fair value investments by level

The following table presents the changes in White Mountains’s fair value measurements for Level 3 investments for the years ended December 31, 2023 and 2022:

Level 3 Investments
Millions																																	Other Long-term Investments												Other Long-term Investments
Balance as of December 31, 2022																																	$	911.6					Balance as of December 31, 2021						$	890.6
Net realized and unrealized gains																																	157.3						Net realized and unrealized gains						60.4
Purchases and contributions																																	256.6						Purchases and contributions						129.8
Sales and distributions																																	(187.3)						Sales and distributions						(169.2)
Transfers in																																	—						Transfers in						—
Transfers out																																	—						Transfers out						—
Balance as of December 31, 2023																																	$	1,138.2					Balance as of December 31, 2022						$	911.6

Schedule of significant unobservable inputs used in estimating the fair value of other long-term investments

The following tables present significant unobservable inputs used in estimating the fair value of White Mountains’s other long-term investments classified within Level 3 as of December 31, 2023 and 2022. The tables below exclude $19.0 million and $41.1 million of Level 3 other long-term investments generally valued based on recent or expected transaction prices. The fair value of investments in private equity funds and hedge funds, bank loan funds, Lloyd’s trust deposits and ILS funds are generally estimated using the NAV of the funds.

$ in Millions

December 31, 2023

Description

Valuation Technique(s) (1)

Fair Value (2)

Unobservable Inputs

Discount Rate (6)

Terminal Cash Flow Exit Multiple (x) or Terminal Revenue Growth Rate (%) (6)

Kudu’s Participation Contracts (3)(4)(5)

Discounted cash flow

$890.5

18% - 25%

7x - 22x

PassportCard/DavidShield

Discounted cash flow

$150.0

24%

4%

Elementum Holdings, L.P.

Discounted cash flow

$35.0

21%

4%

Preferred securities

Discounted cash flow

$28.2

8%

N/A

Private debt instruments

Discounted cash flow

$15.5

11% - 12%

N/A

(1) Key inputs to the discounted cash flow analysis generally include projections of future revenue and earnings, discount rates and terminal exit multiples or growth rates.

(2) Includes the net unrealized investment gains (losses) associated with foreign currency; foreign currency effects based on observable inputs.

(3) Since Kudu’s Participation Contracts are not subject to corporate taxes within Kudu Investment Management, LLC, pre-tax discount rates are applied to pre-tax cash flows in determining fair values. The weighted average discount rate and weighted average terminal cash flow exit multiple applied to Kudu’s Participation Contracts was 20% and 13x.

(4) In 2023, Kudu deployed a total of $163.8 into new and existing Participation Contracts.

(5) As of December 31, 2023, one of Kudu’s Participation Contracts with a total fair value of $69.1 was valued using a probability weighted expected return method, which takes into account factors such as a discounted cash flow analysis, the expected value to be received in a pending sales transaction and the likelihood that a sales transaction will take place.

(6) Increases (decreases) to the discount rates in isolation would result in lower (higher) fair value measurements, while increases (decreases) to the terminal cash flow exit multiples or terminal revenue growth rates in isolation would result in higher (lower) fair value measurements.

$ in Millions

December 31, 2022

Description

Valuation Technique(s) (1)

Fair Value (2)

Unobservable Inputs

Discount Rate (6)

Terminal Cash Flow Exit Multiple (x) or Terminal Revenue Growth Rate (%) (6)

Kudu’s Participation Contracts (3)(4)(5)

Discounted cash flow

$695.9

18% - 25%

7x - 16x

PassportCard/DavidShield

Discounted cash flow

$135.0

24%

4%

Elementum Holdings, L.P.

Discounted cash flow

$30.0

21%

4%

Private debt instruments

Discounted cash flow

$9.6

11%

N/A

(1) Key inputs to the discounted cash flow analysis generally include projections of future revenue and earnings, discount rates and terminal exit multiples or growth rates.

(2) Includes the net unrealized investment gains (losses) associated with foreign currency; foreign currency effects based on observable inputs.

(3) Since Kudu’s Participation Contracts are not subject to corporate taxes within Kudu Investment Management, LLC, pre-tax discount rates are applied to pre-tax cash flows in determining fair values. The weighted average discount rate and weighted average terminal cash flow exit multiple applied to Kudu’s Participation Contracts is 21% and 12x.

(4) In 2022, Kudu deployed a total of $99.8 into new and existing Participation Contracts.

(5) As of December 31, 2022, two of Kudu’s Participation Contracts with a total fair value of $189.0 were valued using a probability weighted expected return method, which takes into account factors such as a discounted cash flow analysis, the expected value to be received in a pending sales transaction and the likelihood that a sales transaction will take place.

(6) Increases (decreases) to the discount rates in isolation would result in lower (higher) fair value measurements, while increases (decreases) to the terminal cash flow exit multiples or terminal revenue growth rates in isolation would result in higher (lower) fair value measurements.

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- Definition

Tabular disclosure of input and valuation technique used to measure fair value and change in valuation approach and technique for each separate class of asset and liability measured on recurring and nonrecurring basis.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-SubTopic 10
-Topic 820
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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- Definition

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