v3.26.1
Investment Securities (Tables)
3 Months Ended
Mar. 31, 2026
Investments, Debt and Equity Securities [Abstract]  
Schedule of pre-tax net investment income
The following table presents pre-tax net investment income for the three months ended March 31, 2026 and 2025:
Three Months Ended March 31,
Millions20262025
Fixed maturity investments$30.6 $27.0 
Short-term investments15.6 10.6 
Common equity securities.5 .4 
Other long-term investments25.2 22.2 
Total investment income71.9 60.2 
Third-party investment expenses(.5)(.6)
Net investment income, pre-tax$71.4 $59.6 
Schedule of net realized and unrealized investment gains and losses
The following table presents net realized and unrealized investment gains (losses) for the three months ended March 31, 2026 and 2025:
Three Months Ended March 31,
Millions20262025
Realized investment gains (losses)
Fixed maturity investments$1.0 $(.1)
Short-term investments .2 
Common equity securities11.2 34.6 
Other long-term investments2.1 5.6 
Net realized investment gains (losses) (1)
14.3 40.3 
Unrealized investment gains (losses)
Fixed maturity investments(23.0)22.2 
Short-term investments(.7)— 
Common equity securities(35.9)(22.1)
Investment in MediaAlpha(65.2)(36.6)
Other long-term investments56.1 46.2 
Net unrealized investment gains (losses)(68.7)9.7 
Net realized and unrealized investment gains (losses) (2)
$(54.4)$50.0 
Fixed maturity and short-term investments
   Net realized and unrealized investment gains (losses)$(22.7)$22.3 
Less: net realized and unrealized gains (losses) on investment
   securities sold during the period
 .5 
Net unrealized investment gains (losses) recognized during the period on
   investment securities held at the end of the period
$(22.7)$21.8 
Common equity securities and investment in MediaAlpha
Net realized and unrealized investment gains (losses) on common
   equity securities
$(24.7)$12.5 
Net realized and unrealized investment gains (losses) from
    investment in MediaAlpha
(65.2)(36.6)
Total net realized and unrealized investment gains (losses) (89.9)(24.1)
Less: net realized and unrealized gains (losses) on investment
   securities sold during the period
.2 3.0 
Net unrealized investment gains (losses) recognized during the period on
   investment securities held at the end of the period
$(90.1)$(27.1)
(1) For the three months ended March 31, 2026 and 2025, includes $(6.4) and $7.2 of net realized and unrealized investment gains (losses) related to foreign currency exchange.
(2) For the three months ended March 31, 2026 and 2025, White Mountains recognized gross realized investment gains of $19.4 and $41.4 and gross realized investment losses of $5.1 and $1.1 on sales of investment securities.

The following table presents total net unrealized gains (losses) attributable to Level 3 investments for the three months ended March 31, 2026 and 2025 for investments still held at the end of the period:
Three Months Ended March 31,
Millions20262025
Total net unrealized investment gains (losses) recognized during the period on Level 3 investments held at the end of period
$50.1 $45.0 
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 March 31, 2026 and December 31, 2025:
 March 31, 2026
MillionsCost or
Amortized
Cost
Gross
Unrealized
Gains
Gross
Unrealized
Losses
Net Foreign
Currency Gains (Losses)
Carrying
Value
U.S. Government and agency obligations$480.1 $.5 $(2.9)$ $477.7 
Debt securities issued by corporations1,640.1 5.9 (18.5)1.3 1,628.8 
Mortgage and asset-backed securities417.2 2.3 (17.0) 402.5 
Collateralized loan obligations344.7 .3 (.6).8 345.2 
Foreign government and agency obligations31.1  (.3)1.1 31.9 
Total fixed maturity investments
$2,913.2 $9.0 $(39.3)$3.2 $2,886.1 

 December 31, 2025
MillionsCost or
Amortized
Cost
Gross
Unrealized
Gains
Gross
Unrealized
Losses
Net Foreign
Currency
Gains (Losses)
Carrying
Value
U.S. Government and agency obligations$459.7 $1.3 $(.7)$— $460.3 
Debt securities issued by corporations1,534.9 13.5 (11.5).8 1,537.7 
Mortgage and asset-backed securities405.1 4.2 (16.3)— 393.0 
Collateralized loan obligations343.9 .8 (.1)2.4 347.0 
Foreign government and agency obligations31.2 — (.1)1.4 32.5 
Total fixed maturity investments
$2,774.8 $19.8 $(28.7)$4.6 $2,770.5 
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 March 31, 2026 and December 31, 2025:
 March 31, 2026
MillionsCost or
Amortized
Cost
Gross
Unrealized
Gains
Gross
Unrealized
Losses
Net Foreign
Currency Gains (Losses)
Carrying
Value
Common equity securities$483.8 $73.4 $(7.6)$(3.1)$546.5 
Investment in MediaAlpha$59.2 $106.9 $ $ $166.1 
Other long-term investments$2,617.8 $782.7 $(133.9)$(13.1)$3,253.5 

 December 31, 2025
MillionsCost or
Amortized
Cost
Gross
Unrealized
Gains
Gross
Unrealized
Losses
Net Foreign
Currency
Gains (Losses)
Carrying
Value
Common equity securities$384.3 $99.9 $— $(1.2)$483.0 
Investment in MediaAlpha$59.2 $172.0 $— $— $231.2 
Other long-term investments$2,378.8 $712.6 $(123.1)$(9.8)$2,958.5 
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 March 31, 2026 and December 31, 2025. Actual maturities could differ from contractual maturities because borrowers may have the right to call or prepay certain obligations with or without penalties.
March 31, 2026December 31, 2025
MillionsCost or Amortized CostCarrying ValueCost or Amortized CostCarrying Value
Due in one year or less$511.0 $511.1 $455.3 $455.2 
Due after one year through five years1,368.6 1,359.2 1,349.8 1,354.1 
Due after five years through ten years257.0 253.6 199.0 199.3 
Due after ten years14.7 14.5 21.7 21.9 
Mortgage and asset-backed securities and
   collateralized loan obligations
761.9 747.7 749.0 740.0 
Total fixed maturity investments$2,913.2 $2,886.1 $2,774.8 $2,770.5 
Schedule of fair value measurements for investment securities by level
The following tables present White Mountains’s fair value measurements for investments by security type and level as of March 31, 2026 and December 31, 2025:
 March 31, 2026
MillionsFair ValueLevel 1Level 2Level 3
Fixed maturity investments:    
U.S. Government and agency obligations$477.7 $477.7 $ $ 
Debt securities issued by corporations:
Financials589.4  589.4  
Consumer326.0  326.0  
Industrial151.8  151.8  
Healthcare142.9  142.9  
Technology113.6  113.6  
Utilities99.9  99.9  
Materials80.5  80.5  
Communications68.4  68.4  
Energy56.3  56.3  
Total debt securities issued by corporations1,628.8  1,628.8  
Mortgage and asset-backed securities402.5  402.5  
Collateralized loan obligations345.2  345.2  
Foreign government and agency obligations31.9  31.9  
Total fixed maturity investments2,886.1 477.7 2,408.4  
Short-term investments1,501.8 1,496.8 5.0  
Common equity securities:
Exchange-traded funds147.3 147.3   
Other (1)
399.2  399.2  
Total common equity securities
546.5 147.3 399.2  
Investment in MediaAlpha166.1 166.1   
Other long-term investments2,050.4  33.9 2,016.5 
Other long-term investments net asset value (2)
1,203.1    
Total other long-term investments3,253.5  33.9 2,016.5 
Total investments $8,354.0 $2,287.9 $2,846.5 $2,016.5 
(1) Consists of investments in listed funds that predominantly invest in international equities.
(2) Consists of investments in the BroadStreet SPV, private equity funds and hedge funds, a bank loan fund, Lloyd’s trust deposits and insurance-linked securities (“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, 2025
MillionsFair ValueLevel 1Level 2Level 3
Fixed maturity investments:    
U.S. Government and agency obligations$460.3 $460.3 $— $— 
Debt securities issued by corporations:
Financials531.5 — 531.5 — 
Consumer306.2 — 306.2 — 
Industrial150.0 — 150.0 — 
Healthcare146.1 — 146.1 — 
Technology98.4 — 98.4 — 
Utilities90.4 — 90.4 — 
Materials78.7 — 78.7 — 
Communications76.3 — 76.3 — 
Energy60.1 — 60.1 — 
Total debt securities issued by corporations1,537.7 — 1,537.7 — 
Mortgage and asset-backed securities393.0 — 393.0 — 
Collateralized loan obligations347.0 — 347.0 — 
Foreign government and agency obligations32.5 — 32.5 — 
Total fixed maturity investments2,770.5 460.3 2,310.2 — 
Short-term investments1,881.7 1,871.7 10.0 — 
Common equity securities:
Exchange-traded funds30.7 30.7 — — 
Other (1)
452.3 — 452.3 — 
Total common equity securities483.0 30.7 452.3 — 
Investment in MediaAlpha231.2 231.2 — — 
Other long-term investments1,848.1 — 33.7 1,814.4 
Other long-term investments NAV (2)
1,110.4 — — — 
Total other long-term investments2,958.5 — 33.7 1,814.4 
Total investments$8,324.9 $2,593.9 $2,806.2 $1,814.4 
(1) Consists of investments in listed funds that predominantly invest in international equities.
(2) Consists of investments in the BroadStreet SPV, 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 fair values for credit ratings of debt securities issued by corporations held in White Mountains’s investment portfolio as of March 31, 2026 and December 31, 2025:
Fair Value at
MillionsMarch 31, 2026December 31, 2025
AAA$7.3 $7.8 
AA85.5 89.9 
A767.1 711.7 
BBB755.4 716.9 
BB5.5 3.2 
Other8.0 8.2 
Debt securities issued by corporations (1)
$1,628.8 $1,537.7 
(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 March 31, 2026 and December 31, 2025:
 March 31, 2026December 31, 2025
MillionsFair ValueLevel 2Level 3Fair ValueLevel 2Level 3
Mortgage-backed securities:      
Agency:      
FNMA$201.2 $201.2 $ $192.1 $192.1 $— 
FHLMC136.2 136.2  141.3 141.3 — 
GNMA20.0 20.0  20.6 20.6 — 
   Total agency (1)
357.4 357.4  354.0 354.0 — 
   Total mortgage-backed securities357.4 357.4  354.0 354.0 — 
Other asset-backed securities:
Vehicle receivables26.2 26.2  21.9 21.9 — 
Credit card receivables13.9 13.9  14.0 14.0 — 
Other5.0 5.0  3.1 3.1 — 
Total other asset-backed securities45.1 45.1  39.0 39.0 — 
Total mortgage and asset-backed securities402.5402.5 393.0393.0— 
Collateralized loan obligations345.2 345.2  347.0 347.0 — 
Total mortgage and asset-backed securities
   and collateralized loan obligations
$747.7 $747.7 $ $740.0 $740.0 $— 
(1)    Represents publicly traded mortgage-backed securities which carry the full faith and credit guarantee 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
The following tables present the carrying values of White Mountains’s other long-term investments by reportable segment as of March 31, 2026 and December 31, 2025:
Fair Value as of March 31, 2026
MillionsArk/ WM OutriggerKuduOtherTotal
Kudu’s Participation Contracts $ $1,352.2 $ $1,352.2 
Bamboo SPV
— — 260.0 260.0 
BroadStreet SPV
  170.1 170.1 
PassportCard/DavidShield
  170.0 170.0 
Bishop Street
  125.0 125.0 
Other unconsolidated entities (1)
  113.5 113.5 
Total unconsolidated entities 1,352.2 838.6 2,190.8 
Private equity funds and hedge funds219.6  257.2 476.8 
Bank loan fund307.8   307.8 
Lloyd’s trust deposits 176.4   176.4 
ILS funds  51.0 51.0 
Private debt instruments 6.6 10.2 16.8 
Other33.9   33.9 
Total other long-term investments$737.7 $1,358.8 $1,157.0 $3,253.5 
(1) Includes White Mountains’s noncontrolling equity interests in certain preferred securities, common shares, limited partnership units and limited liability company units.
Fair Value as of December 31, 2025
MillionsArk/ WM OutriggerKuduOtherTotal
Kudu’s Participation Contracts $— $1,285.0 $— $1,285.0 
Bamboo SPV
— — 250.0 250.0 
BroadStreet SPV
— — 160.0 160.0 
PassportCard/DavidShield
— — 170.0 170.0 
Other unconsolidated entities (1)
— — 108.7 108.7 
Total unconsolidated entities— 1,285.0 688.7 1,973.7 
Private equity funds and hedge funds167.1 — 228.1 395.2 
Bank loan fund308.5 — — 308.5 
Lloyd’s trust deposits 180.4 — — 180.4 
ILS funds— — 50.1 50.1 
Private debt instruments— 6.4 10.5 16.9 
Other33.7 — — 33.7 
Total other long-term investments$689.7 $1,291.4 $977.4 $2,958.5 
(1) Includes White Mountains’s noncontrolling equity interests in certain preferred securities, common shares, limited partnership units and limited liability company units.
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 March 31, 2026 and December 31, 2025:
 March 31, 2026December 31, 2025
MillionsFair ValueUnfunded
Commitments
Fair ValueUnfunded
Commitments
Private equity funds    
Aerospace/Defense/Government$138.1 $38.0 $144.0 $39.9 
Financial services108.0 20.8 104.2 23.7 
Real estate3.0 2.2 3.0 2.2 
Total private equity funds249.1 61.0 251.2 65.8 
Hedge funds   
Long/short all cap global162.6  110.6 — 
Long/short equity financials and business services65.1  33.4 — 
Total hedge funds227.7  144.0 — 
Total private equity funds and hedge funds$476.8 $61.0 $395.2 $65.8 
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 March 31, 2026:
Millions1 – 3 years3 – 5 years5 – 10 yearsTotal
Private equity funds — expected lock-up period remaining$54.7$7.8$186.6$249.1
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 three months ended March 31, 2026 and 2025:
Level 3 Investments
Other long-term investments
MillionsMarch 31, 2026March 31, 2025
Beginning balance
$1,814.4 $1,262.7 
Net realized and unrealized gains50.1 45.0 
Purchases and contributions152.0 68.2 
Sales and distributions — 
Transfers in — 
Transfers out — 
Ending balance
$2,016.5 $1,375.9 
Schedule of significant unobservable inputs used in estimating the fair value of investment securities
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 March 31, 2026 and December 31, 2025. The tables below exclude $125.4 million and $250.4 million of Level 3 other long-term investments generally valued based on recent or expected transaction prices. As of December 31, 2025, the Bamboo SPV was measured at fair value based on the value implied in the Bamboo Sale Transaction. See Note 2 — “Significant Transactions.” The fair value of investments in the BroadStreet SPV, private equity funds and hedge funds, bank loan funds, Lloyd’s trust deposits and ILS funds are generally estimated using NAV. Investments for which fair value is measured at NAV are not classified within the fair value hierarchy.
$ in Millions
March 31, 2026
Description
Valuation Technique(s) (1)
Fair Value (2)
Unobservable Inputs
Discount Rate (5)
Terminal Cash Flow Exit Multiple (x) or Terminal Revenue Growth Rate (%) (5)
Kudu’s Participation Contracts (3) (4)
Discounted cash flow
$1,352.2
16% - 24%
7x - 22x
Bamboo SPV
Discounted cash flow
$260.016%4%
PassportCard/DavidShieldDiscounted cash flow$170.024%4%
Private common shares and units
Discounted cash flow
$56.9
22% - 35%
3% - 4%
Private preferred securities
Discounted cash flow$35.615%N/A
Private debt instrumentsDiscounted cash flow$16.4
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 19% and 14x.
(4) In the first three months of 2026, Kudu contributed $25.4 into new and existing Participation Contracts.
(5) 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 MillionsDecember 31, 2025
Description
Valuation Technique(s) (1)
Fair Value (2)
Unobservable Inputs
Discount Rate (5)
Terminal Cash Flow Exit Multiple (x) or Terminal Revenue Growth Rate (%) (5)
Kudu’s Participation Contracts (3) (4)
Discounted cash flow
$1,285.0
16% - 25%
7x - 22x
PassportCard/DavidShield Discounted cash flow$170.024%4%
Private common shares and units
Discounted cash flow$56.9
22% - 35%
3% - 4%
Private preferred securities
Discounted cash flow$35.68%N/A
Private debt instrumentsDiscounted cash flow$16.5
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 19% and 14x.
(4) In 2025, Kudu contributed $201.7 into new and existing Participation Contracts.
(5) 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.