XML 52 R31.htm IDEA: XBRL DOCUMENT
v3.25.1

Investment Securities (Tables) | 3 Months Ended
--- | ---
Mar. 31, 2025
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, 2025 and 2024:
|  |  |  | Three Months Ended March 31,
Millions |  |  |  |  |  | 2025 |  | 2024
Fixed maturity investments |  |  |  |  |  | $ | 27.0 |  |  | $ | 20.9 |
Short-term investments |  |  |  |  |  | 10.6 |  |  | 15.7 |
Common equity securities |  |  |  |  |  | .4 |  |  | .5 |
Other long-term investments |  |  |  |  |  | 22.2 |  |  | 20.6 |
Total investment income |  |  |  |  |  | 60.2 |  |  | 57.7 |
Third-party investment expenses |  |  |  |  |  | (.6) |  |  | (.7) |
Net investment income, pre-tax |  |  |  |  |  | $ | 59.6 |  |  | $ | 57.0 |
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, 2025 and 2024:
|  |  |  | Three Months Ended March 31,
Millions |  |  |  |  |  | 2025 |  | 2024
Realized investment gains (losses) |  |  |  |  |  |  |  |
Fixed maturity investments |  |  |  |  |  | $ | (.1) |  |  | $ | (5.8) |
Short-term investments |  |  |  |  |  | .2 |  |  | (.2) |
Common equity securities |  |  |  |  |  | 34.6 |  |  | — |
Other long-term investments |  |  |  |  |  | 5.6 |  |  | .3 |
Net realized investment gains (losses) |  |  |  |  |  | 40.3 |  |  | (5.7) |
Unrealized investment gains (losses) |  |  |  |  |  |  |  |
Fixed maturity investments |  |  |  |  |  | 22.2 |  |  | (7.4) |
Short-term investments |  |  |  |  |  | — |  |  | (1.0) |
Common equity securities |  |  |  |  |  | (22.1) |  |  | 23.1 |
Investment in MediaAlpha |  |  |  |  |  | (36.6) |  |  | 210.7 |
Other long-term investments |  |  |  |  |  | 46.2 |  |  | 7.1 |
Net unrealized investment gains (losses) |  |  |  |  |  | 9.7 |  |  | 232.5 |
Net realized and unrealized investment gains (losses) (1) |  |  |  |  |  | $ | 50.0 |  |  | $ | 226.8 |
Fixed maturity and short-term investments |  |  |  |  |  |  |  |
Net realized and unrealized investment gains (losses) |  |  |  |  |  | $ | 22.3 |  |  | $ | (14.4) |
Less: net realized and unrealized gains (losses) on investment securities sold during the period |  |  |  |  |  | .5 |  |  | (.7) |
Net unrealized investment gains (losses) recognized during the period on investment securities held at the end of the period |  |  |  |  |  | $ | 21.8 |  |  | $ | (13.7) |
Common equity securities and investment in MediaAlpha |  |  |  |  |  |  |  |
Net realized and unrealized investment gains (losses) on common equity securities |  |  |  |  |  | $ | 12.5 |  |  | $ | 23.1 |
Net realized and unrealized investment gains (losses) from investment in MediaAlpha |  |  |  |  |  | (36.6) |  |  | 210.7 |
Total net realized and unrealized investment gains (losses) |  |  |  |  |  | (24.1) |  |  | 233.8 |
Less: net realized and unrealized gains (losses) on investment securities sold during the period |  |  |  |  |  | 3.0 |  |  | — |
Net unrealized investment gains (losses) recognized during the period on investment securities held at the end of the period |  |  |  |  |  | $ | (27.1) |  |  | $ | 233.8 |
(1) For the three months ended March 31, 2025 and 2024, includes $7.2 and $(11.5) 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 three months ended March 31, 2025 and 2024 for investments still held at the end of the period:
|  |  |  | Three Months Ended March 31,
Millions |  |  |  |  |  | 2025 |  | 2024
Total net unrealized investment gains on other long-term investments held at the end of period, pre-tax |  |  |  |  |  | $ | 45.0 |  |  | $ | (6.2) |
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, 2025 and December 31, 2024:
|  | March 31, 2025
Millions |  | Cost or Amortized Cost |  | Gross Unrealized Gains |  | Gross Unrealized Losses |  | Net Foreign Currency Gains (Losses) |  | Carrying Value
U.S. Government and agency obligations |  | $ | 489.0 |  |  | $ | 2.3 |  |  | $ | (.4) |  |  | $ | — |  |  | $ | 490.9 |
Debt securities issued by corporations |  | 1,415.5 |  |  | 8.2 |  |  | (22.3) |  |  | (2.9) |  |  | 1,398.5 |
Municipal obligations |  | 3.2 |  |  | — |  |  | — |  |  | — |  |  | 3.2 |
Mortgage and asset-backed securities |  | 399.6 |  |  | 1.3 |  |  | (21.0) |  |  | — |  |  | 379.9 |
Collateralized loan obligations |  | 256.7 |  |  | .4 |  |  | (.6) |  |  | (.5) |  |  | 256.0 |
Foreign government and agency obligations |  | 23.4 |  |  | — |  |  | — |  |  | .1 |  |  | 23.5 |
Total fixed maturity investments |  | $ | 2,587.4 |  |  | $ | 12.2 |  |  | $ | (44.3) |  |  | $ | (3.3) |  |  | $ | 2,552.0 |
|  | December 31, 2024
Millions |  | Cost or Amortized Cost |  | Gross Unrealized Gains |  | Gross Unrealized Losses |  | Net Foreign Currency Gains (Losses) |  | Carrying Value
U.S. Government and agency obligations |  | $ | 461.8 |  |  | $ | 1.1 |  |  | $ | (.8) |  |  | $ | — |  |  | $ | 462.1 |
Debt securities issued by corporations |  | 1,444.5 |  |  | 4.6 |  |  | (31.4) |  |  | (3.5) |  |  | 1,414.2 |
Municipal obligations |  | 3.2 |  |  | — |  |  | — |  |  | — |  |  | 3.2 |
Mortgage and asset-backed securities |  | 400.2 |  |  | .2 |  |  | (26.5) |  |  | — |  |  | 373.9 |
Collateralized loan obligations |  | 237.3 |  |  | 1.2 |  |  | (.2) |  |  | (1.6) |  |  | 236.7 |
Foreign government and agency obligations |  | 22.2 |  |  | — |  |  | (.1) |  |  | (.6) |  |  | 21.5 |
Total fixed maturity investments |  | $ | 2,569.2 |  |  | $ | 7.1 |  |  | $ | (59.0) |  |  | $ | (5.7) |  |  | $ | 2,511.6 |
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, 2025 and December 31, 2024:
|  | March 31, 2025
Millions |  | Cost or Amortized Cost |  | Gross Unrealized Gains |  | Gross Unrealized Losses |  | Net Foreign Currency Gains (Losses) |  | Carrying Value
Common equity securities |  | $ | 450.9 |  |  | $ | 95.8 |  |  | $ | — |  |  | $ | (4.9) |  |  | $ | 541.8 |
Investment in MediaAlpha |  | $ | 59.2 |  |  | $ | 105.8 |  |  | $ | — |  |  | $ | — |  |  | $ | 165.0 |
Other long-term investments |  | $ | 1,840.3 |  |  | $ | 596.5 |  |  | $ | (122.8) |  |  | $ | (26.1) |  |  | $ | 2,287.9 |
|  | December 31, 2024
Millions |  | Cost or Amortized Cost |  | Gross Unrealized Gains |  | Gross Unrealized Losses |  | Net Foreign Currency Gains (Losses) |  | Carrying Value
Common equity securities |  | $ | 537.0 |  |  | $ | 120.4 |  |  | $ | — |  |  | $ | (7.4) |  |  | $ | 650.0 |
Investment in MediaAlpha |  | $ | 59.2 |  |  | $ | 142.4 |  |  | $ | — |  |  | $ | — |  |  | $ | 201.6 |
Other long-term investments |  | $ | 1,748.7 |  |  | $ | 546.4 |  |  | $ | (116.7) |  |  | $ | (28.2) |  |  | $ | 2,150.2 |
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, 2025 and December 31, 2024. 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, 2025 |  | December 31, 2024
Millions |  | Cost or Amortized Cost |  | Carrying Value |  | Cost or Amortized Cost |  | Carrying Value
Due in one year or less |  | $ | 318.7 |  |  | $ | 316.4 |  |  | $ | 205.8 |  |  | $ | 203.9 |
Due after one year through five years |  | 1,374.7 |  |  | 1,370.2 |  |  | 1,494.5 |  |  | 1,478.7 |
Due after five years through ten years |  | 219.8 |  |  | 211.4 |  |  | 206.1 |  |  | 193.2 |
Due after ten years |  | 17.9 |  |  | 18.1 |  |  | 25.3 |  |  | 25.2 |
Mortgage and asset-backed securities and collateralized loan obligations |  | 656.3 |  |  | 635.9 |  |  | 637.5 |  |  | 610.6 |
Total fixed maturity investments |  | $ | 2,587.4 |  |  | $ | 2,552.0 |  |  | $ | 2,569.2 |  |  | $ | 2,511.6 |
Schedule of fair value measurements for investment securities by level | The following tables present White Mountains’s fair value measurements for investments as of March 31, 2025 and December 31, 2024 by level. 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, foreign governments and agencies, municipalities, entities issuing mortgage and asset-backed securities or entities issuing collateralized loan obligations 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 U.S. Intermediate Aggregate Index.
|  | March 31, 2025
Millions |  | Fair Value |  | Level 1 |  | Level 2 |  | Level 3
Fixed maturity investments: |  |  |  |  |  |  |  |
U.S. Government and agency obligations |  | $ | 490.9 |  |  | $ | 490.1 |  |  | $ | .8 |  |  | $ | — |
Debt securities issued by corporations: |  |  |  |  |  |  |  |
Financials |  | 474.4 |  |  | — |  |  | 474.4 |  |  | — |
Consumer |  | 263.1 |  |  | — |  |  | 263.1 |  |  | — |
Industrial |  | 150.2 |  |  | — |  |  | 150.2 |  |  | — |
Healthcare |  | 144.2 |  |  | — |  |  | 144.2 |  |  | — |
Technology |  | 119.3 |  |  | — |  |  | 119.3 |  |  | — |
Communications |  | 64.5 |  |  | — |  |  | 64.5 |  |  | — |
Materials |  | 63.8 |  |  | — |  |  | 63.8 |  |  | — |
Utilities |  | 60.7 |  |  | — |  |  | 60.7 |  |  | — |
Energy |  | 58.3 |  |  | — |  |  | 58.3 |  |  | — |
Total debt securities issued by corporations |  | 1,398.5 |  |  | — |  |  | 1,398.5 |  |  | — |
Municipal obligations |  | 3.2 |  |  | — |  |  | 3.2 |  |  | — |
Mortgage and asset-backed securities |  | 379.9 |  |  | — |  |  | 379.9 |  |  | — |
Collateralized loan obligations |  | 256.0 |  |  | — |  |  | 256.0 |  |  | — |
Foreign government and agency obligations |  | 23.5 |  |  | — |  |  | 23.5 |  |  | — |
Total fixed maturity investments |  | 2,552.0 |  |  | 490.1 |  |  | 2,061.9 |  |  | — |
Short-term investments |  | 1,004.6 |  |  | 1,001.0 |  |  | 3.6 |  |  | — |
Common equity securities: |  |  |  |  |  |  |  |
Exchange-traded funds |  | 120.9 |  |  | 120.9 |  |  | — |  |  | — |
Other (1) |  | 420.9 |  |  | — |  |  | 420.9 |  |  | — |
Total common equity securities |  | 541.8 |  |  | 120.9 |  |  | 420.9 |  |  | — |
Investment in MediaAlpha |  | 165.0 |  |  | 165.0 |  |  | — |  |  | — |
Other long-term investments |  | 1,401.4 |  |  | — |  |  | 25.5 |  |  | 1,375.9 |
Other long-term investments — net asset value (2) |  | 886.5 |  |  | — |  |  | — |  |  | — |
Total other long-term investments |  | 2,287.9 |  |  | — |  |  | 25.5 |  |  | 1,375.9 |
Total investments |  | $ | 6,551.3 |  |  | $ | 1,777.0 |  |  | $ | 2,511.9 |  |  | $ | 1,375.9 |
(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 net asset value (“NAV”) as a practical expedient. Investments for which fair value is measured at NAV are not classified within the fair value hierarchy.
|  | December 31, 2024
Millions |  | Fair Value |  | Level 1 |  | Level 2 |  | Level 3
Fixed maturity investments: |  |  |  |  |  |  |  |
U.S. Government and agency obligations |  | $ | 462.1 |  |  | $ | 461.3 |  |  | $ | .8 |  |  | $ | — |
Debt securities issued by corporations: |  |  |  |  |  |  |  |
Financials |  | 466.7 |  |  | — |  |  | 466.7 |  |  | — |
Consumer |  | 255.2 |  |  | — |  |  | 255.2 |  |  | — |
Industrial |  | 164.4 |  |  | — |  |  | 164.4 |  |  | — |
Healthcare |  | 153.1 |  |  | — |  |  | 153.1 |  |  | — |
Technology |  | 113.8 |  |  | — |  |  | 113.8 |  |  | — |
Communications |  | 71.6 |  |  | — |  |  | 71.6 |  |  | — |
Materials |  | 65.7 |  |  | — |  |  | 65.7 |  |  | — |
Utilities |  | 60.9 |  |  | — |  |  | 60.9 |  |  | — |
Energy |  | 62.8 |  |  | — |  |  | 62.8 |  |  | — |
Total debt securities issued by corporations |  | 1,414.2 |  |  | — |  |  | 1,414.2 |  |  | — |
Municipal obligations |  | 3.2 |  |  | — |  |  | 3.2 |  |  | — |
Mortgage and asset-backed securities |  | 373.9 |  |  | — |  |  | 373.9 |  |  | — |
Collateralized loan obligations |  | 236.7 |  |  | — |  |  | 236.7 |  |  | — |
Foreign government and agency obligations |  | 21.5 |  |  | — |  |  | 21.5 |  |  | — |
Total fixed maturity investments |  | 2,511.6 |  |  | 461.3 |  |  | 2,050.3 |  |  | — |
Short-term investments |  | 964.2 |  |  | 951.1 |  |  | 13.1 |  |  | — |
Common equity securities: |  |  |  |  |  |  |  |
Exchange-traded funds |  | 224.6 |  |  | 224.6 |  |  | — |  |  | — |
Other (1) |  | 425.4 |  |  | — |  |  | 425.4 |  |  | — |
Total common equity securities |  | 650.0 |  |  | 224.6 |  |  | 425.4 |  |  | — |
Investment in MediaAlpha |  | 201.6 |  |  | 201.6 |  |  | — |  |  | — |
Other long-term investments |  | 1,286.2 |  |  | — |  |  | 23.5 |  |  | 1,262.7 |
Other long-term investments — NAV (2) |  | 864.0 |  |  | — |  |  | — |  |  | — |
Total other long-term investments |  | 2,150.2 |  |  | — |  |  | 23.5 |  |  | 1,262.7 |
Total investments |  | $ | 6,477.6 |  |  | $ | 1,838.6 |  |  | $ | 2,512.3 |  |  | $ | 1,262.7 |
(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 fair values for credit ratings of debt securities issued by corporations held in White Mountains’s investment portfolio as of March 31, 2025 and December 31, 2024:
|  | Fair Value at
Millions |  | March 31, 2025 |  | December 31, 2024
AAA |  | $ | 11.9 |  |  | $ | 14.6 |
AA |  | 89.5 |  |  | 91.2 |
A |  | 623.7 |  |  | 607.2 |
BBB |  | 659.1 |  |  | 688.7 |
BB |  | 6.8 |  |  | 5.4 |
Other |  | 7.5 |  |  | 7.1 |
Debt securities issued by corporations (1) |  | $ | 1,398.5 |  |  | $ | 1,414.2 |
(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, 2025 and December 31, 2024:
|  | March 31, 2025 |  | December 31, 2024
Millions |  | Fair Value |  | Level 2 |  | Level 3 |  | Fair Value |  | Level 2 |  | Level 3
Mortgage-backed securities: |  |  |  |  |  |  |  |  |  |  |  |
Agency: |  |  |  |  |  |  |  |  |  |  |  |
FNMA |  | $ | 202.7 |  |  | $ | 202.7 |  |  | $ | — |  |  | $ | 198.3 |  |  | $ | 198.3 |  |  | $ | — |
FHLMC |  | 147.5 |  |  | 147.5 |  |  | — |  |  | 147.1 |  |  | 147.1 |  |  | — |
GNMA |  | 24.0 |  |  | 24.0 |  |  | — |  |  | 24.2 |  |  | 24.2 |  |  | — |
Total agency (1) |  | 374.2 |  |  | 374.2 |  |  | — |  |  | 369.6 |  |  | 369.6 |  |  | — |
Non-agency: Commercial |  | .4 |  |  | .4 |  |  | — |  |  | .4 |  |  | .4 |  |  | — |
Total non-agency |  | .4 |  |  | .4 |  |  | — |  |  | .4 |  |  | .4 |  |  | — |
Total mortgage-backed securities |  | 374.6 |  |  | 374.6 |  |  | — |  |  | 370.0 |  |  | 370.0 |  |  | — |
Other asset-backed securities: |  |  |  |  |  |  |  |  |  |  |  |
Vehicle receivables |  | 3.1 |  |  | 3.1 |  |  | — |  |  | 1.7 |  |  | 1.7 |  |  | — |
Credit card receivables |  | .2 |  |  | .2 |  |  | — |  |  | .2 |  |  | .2 |  |  | — |
Other |  | 2.0 |  |  | 2.0 |  |  | — |  |  | 2.0 |  |  | 2.0 |  |  | — |
Total other asset-backed securities |  | 5.3 |  |  | 5.3 |  |  | — |  |  | 3.9 |  |  | 3.9 |  |  | — |
Total mortgage and asset-backed securities |  | 379.9 |  | 379.9 |  | — |  |  | 373.9 |  | 373.9 |  | — |
Collateralized loan obligations |  | 256.0 |  |  | 256.0 |  |  | — |  |  | 236.7 |  |  | 236.7 |  |  | — |
Total mortgage and asset-backed securities and collateralized loan obligations |  | $ | 635.9 |  |  | $ | 635.9 |  |  | $ | — |  |  | $ | 610.6 |  |  | $ | 610.6 |  |  | $ | — |
(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 | The following tables present the carrying values of White Mountains’s other long-term investments by reportable segment as of March 31, 2025 and December 31, 2024:
|  | Fair Value as of March 31, 2025
Millions |  | Ark/ WM Outrigger |  | Kudu |  | Other |  | Total
Kudu’s Participation Contracts |  | $ | — |  |  | $ | 1,120.4 |  |  | $ | — |  |  | $ | 1,120.4 |
PassportCard/DavidShield |  | — |  |  | — |  |  | 150.0 |  |  | 150.0 |
Elementum |  | — |  |  | — |  |  | 35.0 |  |  | 35.0 |
Other unconsolidated entities (1) |  | — |  |  | — |  |  | 64.7 |  |  | 64.7 |
Total unconsolidated entities |  | — |  |  | 1,120.4 |  |  | 249.7 |  |  | 1,370.1 |
Private equity funds and hedge funds |  | 134.8 |  |  | — |  |  | 244.4 |  |  | 379.2 |
Bank loan fund |  | 264.9 |  |  | — |  |  | — |  |  | 264.9 |
Lloyd’s trust deposits |  | 155.9 |  |  | — |  |  | — |  |  | 155.9 |
ILS funds |  | — |  |  | — |  |  | 71.3 |  |  | 71.3 |
Private debt instruments |  | — |  |  | 5.8 |  |  | 9.5 |  |  | 15.3 |
Other |  | 31.2 |  |  | — |  |  | — |  |  | 31.2 |
Total other long-term investments |  | $ | 586.8 |  |  | $ | 1,126.2 |  |  | $ | 574.9 |  |  | $ | 2,287.9 |
(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, 2024
Millions |  | Ark/ WM Outrigger |  | Kudu |  | Other |  | Total
Kudu’s Participation Contracts |  | $ | — |  |  | $ | 1,008.4 |  |  | $ | — |  |  | $ | 1,008.4 |
PassportCard/DavidShield |  | — |  |  | — |  |  | 150.0 |  |  | 150.0 |
Elementum |  | — |  |  | — |  |  | 35.0 |  |  | 35.0 |
Other unconsolidated entities (1) |  | — |  |  | — |  |  | 63.6 |  |  | 63.6 |
Total unconsolidated entities |  | — |  |  | 1,008.4 |  |  | 248.6 |  |  | 1,257.0 |
Private equity funds and hedge funds |  | 104.1 |  |  | — |  |  | 256.5 |  |  | 360.6 |
Bank loan fund |  | 264.7 |  |  | — |  |  | — |  |  | 264.7 |
Lloyd’s trust deposits |  | 149.9 |  |  | — |  |  | — |  |  | 149.9 |
ILS funds |  | — |  |  | — |  |  | 74.0 |  |  | 74.0 |
Private debt instruments |  | — |  |  | 5.6 |  |  | 9.3 |  |  | 14.9 |
Other |  | 29.1 |  |  | — |  |  | — |  |  | 29.1 |
Total other long-term investments |  | $ | 547.8 |  |  | $ | 1,014.0 |  |  | $ | 588.4 |  |  | $ | 2,150.2 |
(1) Includes White Mountains’s noncontrolling equity interests in certain preferred securities, private common equity securities, limited liability company units and SAFE investments.
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, 2025 and December 31, 2024:
|  | March 31, 2025 |  | December 31, 2024
Millions |  | Fair Value |  | Unfunded Commitments |  | Fair Value |  | Unfunded Commitments
Private equity funds |  |  |  |  |  |  |  |
Aerospace/Defense/Government |  | $ | 140.3 |  |  | $ | 48.0 |  |  | $ | 152.4 |  |  | $ | 49.3 |
Financial services |  | 96.6 |  |  | 28.0 |  |  | 93.4 |  |  | 32.0 |
Real estate |  | 3.7 |  |  | 2.4 |  |  | 3.7 |  |  | 2.4 |
Total private equity funds |  | 240.6 |  |  | 78.4 |  |  | 249.5 |  |  | 83.7 |
Hedge funds |  |  |  |  |  |  |  |
Long/short all cap global |  | 80.6 |  |  | — |  |  | 52.0 |  |  | — |
Long/short equity financials and business services |  | 58.0 |  |  | — |  |  | 59.2 |  |  | — |
Total hedge funds |  | 138.6 |  |  | — |  |  | 111.2 |  |  | — |
Total private equity funds and hedge funds |  | $ | 379.2 |  |  | $ | 78.4 |  |  | $ | 360.7 |  |  | $ | 83.7 |
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, 2025:
Millions |  | 1 – 3 years |  | 3 – 5 years |  | 5 – 10 years |  | >10 years |  | Total
Private equity funds — expected lock-up period remaining |  | $14.6 |  | $51.5 |  | $149.6 |  | $24.9 |  | $240.6
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 three months ended March 31, 2025 and 2024:
Level 3 Investments |  |  |  |
Millions |  |  |  |  |  |  |  |  |  |  | Other Long-term Investments |  |  |  | Other Long-term Investments |  |
Balance as of December 31, 2024 |  |  |  |  |  |  |  |  |  |  | $ | 1,262.7 |  |  | Balance as of December 31, 2023 |  | $ | 1,138.2 |  |  |  |  |
Net realized and unrealized gains |  |  |  |  |  |  |  |  |  |  | 45.0 |  |  | Net realized and unrealized gains |  | (5.7) |  |  |  |  |
Purchases and contributions |  |  |  |  |  |  |  |  |  |  | 68.2 |  |  | Purchases and contributions |  | .1 |  |  |  |  |
Sales and distributions |  |  |  |  |  |  |  |  |  |  | — |  |  | Sales and distributions |  | (3.8) |  |  |  |  |
Transfers in |  |  |  |  |  |  |  |  |  |  | — |  |  | Transfers in |  | — |  |  |  |  |
Transfers out |  |  |  |  |  |  |  |  |  |  | — |  |  | Transfers out |  | — |  |  |  |  |
Balance as of March 31, 2025 |  |  |  |  |  |  |  |  |  |  | $ | 1,375.9 |  |  | Balance as of March 31, 2024 |  | $ | 1,128.8 |  |  |  |  |
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, 2025 and December 31, 2024. The tables below exclude $23.6 million and $23.4 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 |  | March 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 |  | $1,120.4 |  | 16% - 24% |  | 7x - 22x
PassportCard/DavidShield |  | Discounted cash flow |  | $150.0 |  | 24% |  | 4%
Elementum |  | Discounted cash flow |  | $35.0 |  | 22% |  | 4%
Preferred securities |  | Discounted cash flow |  | $32.0 |  | 9% |  | N/A
Private debt instruments |  | Discounted cash flow |  | $14.9 |  | 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 2025, Kudu deployed a total of $68.0 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 Millions |  | December 31, 2024
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 |  | $1,008.4 |  | 17% - 25% |  | 7x - 22x
PassportCard/DavidShield |  | Discounted cash flow |  | $150.0 |  | 24% |  | 4%
Elementum |  | Discounted cash flow |  | $35.0 |  | 22% |  | 4%
Preferred securities |  | Discounted cash flow |  | $31.4 |  | 9% |  | N/A
Private debt instruments |  | Discounted cash flow |  | $14.5 |  | 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 2024, Kudu contributed total cash of $103.5 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.

X
- 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://www.xbrl.org/2003/role/exampleRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 103 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482078/820-10-55-103 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 + Details
Name: | us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of assets, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, by class that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 + Details
Name: | us-gaap_FairValueAssetsMeasuredOnRecurringBasisTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the fair value measurement of assets using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets) and gains or losses recognized in other comprehensive income (loss), and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issues, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs), by class of asset. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 101 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482078/820-10-55-101 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-3 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 + Details
Name: | us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of investments in certain entities that calculate net asset value per share or equivalent measured at fair value on a recurring or nonrecurring basis. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 107 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482078/820-10-55-107 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 35 -Paragraph 54B -Publisher FASB -URI https://asc.fasb.org/1943274/2147482134/820-10-35-54B Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-8 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A + Details
Name: | us-gaap_FairValueInvestmentsEntitiesThatCalculateNetAssetValuePerShareTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of realized and unrealized gain (loss) on investment in security. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(9)(a)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(7)(c)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2 + Details
Name: | us-gaap_GainLossOnInvestmentsTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of investment income, including, but not limited to, interest and dividend income and amortization of discount (premium) derived from debt and equity securities. Excludes realized and unrealized gain (loss) on investments. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(8)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(7)(a)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(7)(b)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(9)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2 Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(2)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1 + Details
Name: | us-gaap_InvestmentIncomeTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of maturities of an entity's investments as well as any other information pertinent to the investments. + References No definition available. + Details
Name: | us-gaap_InvestmentsClassifiedByContractualMaturityDateTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_InvestmentsDebtAndEquitySecuritiesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of assets and liabilities, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 + Details
Name: | us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of other investments not readily marketable, including, but not limited to, description of investment, fair value and value as measured by quoted price. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 940 -SubTopic 820 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147478119/940-820-50-1 + Details
Name: | us-gaap_ScheduleOfOtherInvestmentsNotReadilyMarketableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6B -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-6B + Details
Name: | us-gaap_TradingSecuritiesAndCertainTradingAssetsTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of fixed maturity securities by credit quality indicator. + References No definition available. + Details
Name: | wtm_InvestmentFixedMaturitySecuritiesCreditQualityIndicatorsTableTextBlock
Namespace Prefix: | wtm_
Data Type: | dtr-types1:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of expected lock up period of private equity investments. + References No definition available. + Details
Name: | wtm_PrivateEquityLockUpPeriodTableTextBlock
Namespace Prefix: | wtm_
Data Type: | dtr-types1:textBlockItemType
Balance Type: | na
Period Type: | duration