WHITE MOUNTAINS INSURANCE GROUP LTD (WTM)
SIC breadcrumb: Finance, Insurance, And Real Estate > Insurance Carriers > SIC 6331 Fire, Marine & Casualty Insurance
SEC company page: https://www.sec.gov/edgar/browse/?CIK=776867. Latest filing source: 0001628280-26-012603.
Selected Fundamentals
| Metric | Value | Unit | FY | Filed |
|---|---|---|---|---|
| Revenue | 3,735,000,000 | USD | 2025 | 2026-02-27 |
| Net income | 1,106,400,000 | USD | 2025 | 2026-02-27 |
| Assets | 12,306,500,000 | USD | 2025 | 2026-02-27 |
Financials
Annual standardized facts from SEC companyfacts as of latest extracted filing date 2026-02-27. Source: https://data.sec.gov/api/xbrl/companyfacts/CIK0000776867.json. Derived margins, ratios, and free cash flow are computed from the extracted annual SEC facts.
| Metric | 2008 | 2009 | 2010 | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Revenue | 157,700,000 | 373,800,000 | 369,100,000 | 893,400,000 | 895,600,000 | 614,400,000 | 1,157,900,000 | 2,166,700,000 | 2,239,800,000 | 3,735,000,000 | |||
| Net income | -555,300,000 | 470,000,000 | 86,500,000 | -275,400,000 | 792,800,000 | 509,200,000 | 230,400,000 | 1,106,400,000 | |||||
| Diluted EPS | 80.06 | 146.06 | -41.76 | 130.27 | 226.97 | -89.46 | 276.96 | 198.60 | 89.79 | 430.14 | |||
| Operating cash flow | -155,100,000 | 94,600,000 | -31,100,000 | -120,500,000 | -60,600,000 | 38,600,000 | 365,000,000 | 404,100,000 | 586,800,000 | 550,500,000 | |||
| Dividends paid | 5,400,000 | 4,600,000 | 3,800,000 | 3,200,000 | 3,200,000 | 3,100,000 | 3,000,000 | 2,600,000 | 2,500,000 | 2,600,000 | |||
| Share buybacks | 881,300,000 | 714,600,000 | 511,900,000 | 0.00 | 85,200,000 | 107,500,000 | 615,800,000 | 32,700,000 | 7,900,000 | 202,600,000 | |||
| Assets | 6,520,200,000 | 3,659,200,000 | 3,362,600,000 | 3,983,200,000 | 4,831,400,000 | 7,000,700,000 | 7,389,300,000 | 8,385,900,000 | 9,925,600,000 | 12,306,500,000 | |||
| Liabilities | 2,804,200,000 | 298,400,000 | 644,400,000 | 838,500,000 | 1,013,500,000 | 3,296,000,000 | 3,454,300,000 | 3,824,300,000 | 4,794,600,000 | 6,051,400,000 | |||
| Stockholders' equity | 3,582,700,000 | 3,492,500,000 | 2,843,100,000 | 3,261,500,000 | 3,906,000,000 | 3,548,100,000 | 3,746,900,000 | 4,240,500,000 | 4,483,700,000 | 5,425,400,000 |
Ratios
| Metric | 2008 | 2009 | 2010 | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Net margin | -44.82% | 68.47% | 23.50% | 10.29% | 29.62% | ||||||||
| Return on equity | -7.76% | 21.16% | 12.01% | 5.14% | 20.39% | ||||||||
| Return on assets | -3.93% | 10.73% | 6.07% | 2.32% | 8.99% | ||||||||
| Liabilities / equity | 0.78 | 0.09 | 0.23 | 0.26 | 0.26 | 0.93 | 0.92 | 0.90 | 1.07 | 1.12 |
Financial Charts
Quarterly
Quarterly standardized facts from SEC companyfacts as of latest extracted filing date 2026-05-06. Source: https://data.sec.gov/api/xbrl/companyfacts/CIK0000776867.json.
| Quarter | End Date | Revenue | Net Income | Diluted EPS | Method |
|---|---|---|---|---|---|
| 2022-Q2 | 2022-06-30 | -56.80 | reported discrete quarter | ||
| 2022-Q3 | 2022-09-30 | 306.93 | reported discrete quarter | ||
| 2023-Q1 | 2023-03-31 | 69.83 | reported discrete quarter | ||
| 2023-Q2 | 2023-06-30 | 378,400,000 | 19,600,000 | 7.65 | reported discrete quarter |
| 2023-Q3 | 2023-09-30 | 519,600,000 | 23,600,000 | 9.19 | reported discrete quarter |
| 2023-Q4 | 2023-12-31 | 736,800,000 | 286,500,000 | derived Q4 = FY annual - nine-month YTD | |
| 2024-Q1 | 2024-03-31 | 647,300,000 | 236,400,000 | 92.33 | reported discrete quarter |
| 2024-Q2 | 2024-06-30 | 395,400,000 | -54,600,000 | -21.24 | reported discrete quarter |
| 2024-Q3 | 2024-09-30 | 839,100,000 | 179,000,000 | 69.68 | reported discrete quarter |
| 2024-Q4 | 2024-12-31 | 358,000,000 | -130,400,000 | derived Q4 = FY annual - nine-month YTD | |
| 2025-Q1 | 2025-03-31 | 577,800,000 | 33,900,000 | 13.19 | reported discrete quarter |
| 2025-Q2 | 2025-06-30 | 689,200,000 | 122,900,000 | 47.75 | reported discrete quarter |
| 2025-Q3 | 2025-09-30 | 864,200,000 | 113,800,000 | 44.18 | reported discrete quarter |
| 2025-Q4 | 2025-12-31 | 1,603,800,000 | 835,800,000 | derived Q4 = FY annual - nine-month YTD | |
| 2026-Q1 | 2026-03-31 | 517,800,000 | -27,200,000 | -12.59 | reported discrete quarter |
Quarterly Charts
Macro Cross-References
- CPIAUCSL - Consumer Price Index for All Urban Consumers: All Items in U.S. City Average
- UNRATE - Unemployment Rate
- FEDFUNDS - Federal Funds Effective Rate
- CES0500000003 - Average Hourly Earnings of All Employees, Total Private
- DFEDTARU - Federal Funds Target Range - Upper Limit
- DFEDTARL - Federal Funds Target Range - Lower Limit
- DGS3MO - Market Yield on U.S. Treasury Securities at 3-Month Constant Maturity
- DGS2 - Market Yield on U.S. Treasury Securities at 2-Year Constant Maturity
- DGS10 - Market Yield on U.S. Treasury Securities at 10-Year Constant Maturity
- DGS30 - Market Yield on U.S. Treasury Securities at 30-Year Constant Maturity
- T10Y2Y - 10-Year Treasury Constant Maturity Minus 2-Year Treasury Constant Maturity
- CPILFESL - Consumer Price Index for All Urban Consumers: All Items Less Food and Energy
- CPIUFDSL - Consumer Price Index for All Urban Consumers: Food
- CPIENGSL - Consumer Price Index for All Urban Consumers: Energy
- CUSR0000SAH1 - Consumer Price Index for All Urban Consumers: Shelter
- PCEPI - Personal Consumption Expenditures: Chain-type Price Index
- PCEPILFE - Personal Consumption Expenditures Excluding Food and Energy: Chain-type Price Index
- PPIACO - Producer Price Index by Commodity: All Commodities
- T10YIE - 10-Year Breakeven Inflation Rate
- U6RATE - Total Unemployed, Plus All Marginally Attached Workers Plus Total Employed Part Time for Economic Reasons
- PAYEMS - All Employees, Total Nonfarm
- CIVPART - Labor Force Participation Rate
- EMRATIO - Employment-Population Ratio
- UNEMPLOY - Unemployed
- CE16OV - Employment Level
- ICSA - Initial Claims
- JTSJOL - Job Openings: Total Nonfarm
- JTSQUR - Quits: Total Nonfarm
- GDPC1 - Real Gross Domestic Product
- A191RL1Q225SBEA - Real Gross Domestic Product: Percent Change from Preceding Period
- INDPRO - Industrial Production: Total Index
- TCU - Capacity Utilization: Total Index
- HOUST - New Privately-Owned Housing Units Started: Total Units
- PERMIT - New Privately-Owned Housing Units Authorized in Permit-Issuing Places: Total Units
- RSAFS - Advance Retail Sales: Retail Trade
- PCE - Personal Consumption Expenditures
- DSPIC96 - Real Disposable Personal Income
- PSAVERT - Personal Saving Rate
- M2SL - M2
- BOPGSTB - U.S. International Trade in Goods and Services: Balance
- MSPUS - Median Sales Price of Houses Sold for the United States
- HSN1F - New One Family Houses Sold: United States
- RHORUSQ156N - Homeownership Rate in the United States
- TTLCONS - Total Construction Spending: Total Construction in the United States
- RRVRUSQ156N - Rental Vacancy Rate in the United States
- TOTALSL - Total Consumer Credit Owned and Securitized
- REVOLSL - Revolving Consumer Credit Owned and Securitized
- DRCCLACBS - Delinquency Rate on Credit Card Loans, All Commercial Banks
- GDP - Gross Domestic Product
- GPDI - Gross Private Domestic Investment
- GCE - Government Consumption Expenditures and Gross Investment
- PCEC - Personal Consumption Expenditures
- NETEXP - Net Exports of Goods and Services
- GFDEBTN - Federal Debt: Total Public Debt
- GFDEGDQ188S - Federal Debt: Total Public Debt as Percent of Gross Domestic Product
- FYFSD - Federal Surplus or Deficit
- FGRECPT - Federal Government Current Receipts
- FGEXPND - Federal Government: Current Expenditures
- MANEMP - All Employees, Manufacturing
- USCONS - All Employees, Construction
- USTRADE - All Employees, Retail Trade
- USFIRE - All Employees, Financial Activities
- USGOVT - All Employees, Government
- AWHAETP - Average Weekly Hours of All Employees, Total Private
- DGORDER - Manufacturers' New Orders: Durable Goods
- NEWORDER - Manufacturers' New Orders: Nondefense Capital Goods Excluding Aircraft
- BUSINV - Total Business Inventories
- EXPGS - Exports of Goods and Services
- IMPGS - Imports of Goods and Services
- IR - Import Price Index (End Use): All Commodities
- PPIFIS - Producer Price Index by Commodity: Final Demand
Latest quarter (10-Q)
Latest 10-Q source: 0001628280-26-030935.
Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations. The following discussion contains “forward-looking statements.” White Mountains intends statements that are not historical in nature, which are hereby identified as forward-looking statements, to be covered by the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. White Mountains cannot promise that its expectations in such forward-looking statements will turn out to be correct. White Mountains’s actual results could be materially different from and worse than its expectations. See “FORWARD-LOOKING STATEMENTS” on page 72 for specific important factors that could cause actual results to differ materially from those contained in forward-looking statements. The following discussion also includes eight non-GAAP financial measures: (i) Ark’s tangible book value, (ii) Ark’s tangible capital, (iii) Kudu’s earnings before interest, taxes, depreciation and amortization (“EBITDA”), (iv) Kudu’s adjusted EBITDA, (v) Distinguished’s ScaleCo net income (loss), (vi) Distinguished’s ScaleCo EBITDA (vii) Distinguished’s ScaleCo adjusted EBITDA and (viii) total consolidated portfolio return excluding MediaAlpha. These non-GAAP financial measures have been reconciled from their most comparable GAAP financial measures on page 70. White Mountains believes these measures to be useful in evaluating White Mountains’s financial performance and condition. RESULTS OF OPERATIONS FOR THE THREE MONTHS ENDED MARCH 31, 2026 and 2025 Overview White Mountains reported book value per share of $2,170 as of March 31, 2026, a decrease of 1% for the first quarter of 2026, including dividends. Results in the first quarter of 2026 were driven primarily by solid results from White Mountains’s operating businesses that were more than offset by a decline in the MediaAlpha share price. White Mountains reported book value per share of $1,752 as of March 31, 2025, an increase of 0.4% in the first quarter of 2025, including dividends. Results in the first quarter of 2025 were driven primarily by solid results from White Mountains’s operating businesses and good investment returns, mostly offset by a decline in the MediaAlpha share price. Comprehensive income (loss) attributable to common shareholders was $(27) million in the first quarter 2026 compared to $35 million in the first quarter of 2025. Results in the first quarter of 2026 included $11 million of net realized and unrealized investment gains compared to $87 million in the first quarter of 2025. Results in the first quarter 2026 also included $65 million of unrealized investment losses from White Mountains’s investment in MediaAlpha compared to $37 million in the first quarter of 2025. On February 26, 2026, White Mountains deployed $125 million into Bishop Street, a diversified platform of MGAs and niche underwriting teams focused on the property and casualty insurance sector. In the second quarter of 2026, WTM Partners closed two new acquisitions. The acquisition of BaseSix Systems LLC, a low voltage electrical systems integrator, closed on April 1, 2026 and represented an equity investment of approximately $97 million. The acquisition of Hawkeye Electric, LLC, a provider of specialty electrical contracting services, closed on May 1, 2026 and represented an equity investment of approximately $35 million. Including these deployments, undeployed capital stands at roughly $0.8 billion. The Ark/WM Outrigger segment’s combined ratio was 91% in the first quarter of 2026 compared to 97% in the first quarter of 2025. The Ark/WM Outrigger segment reported gross written premiums of $1,091 million, net written premiums of $590 million and net earned premiums of $374 million in the first quarter of 2026 compared to gross written premiums of $1,108 million, net written premiums of $728 million and net earned premiums of $358 million in the first quarter of 2025. The Ark/WM Outrigger segment reported pre-tax income of $9 million in the first quarter of 2026 compared to $46 million in the first quarter of 2025. Ark’s combined ratio was 91% in the first quarter of 2026 compared to 94% in the first quarter of 2025. Ark’s combined ratio in the first quarter of 2026 included seven points of catastrophe losses, driven by losses related to the war in Iran. This compares to 25 points of catastrophe losses in the first quarter of 2025, driven by losses related to the California wildfires. Ark’s combined ratio included five points of net favorable prior year development in the first quarter of 2026, driven primarily by the specialty and property lines of business. This compares to 14 points of net favorable prior year development in the first quarter of 2025, driven primarily by the marine & energy and property lines of business. Ark has exposure to the war in Iran, primarily through the specialty and marine & energy lines of business. In the first quarter of 2026, Ark recorded estimated losses of $25 million (net of reinsurance and reinstatement premiums). However, losses could increase as the war is ongoing. 47 Ark reported gross written premiums of $1,091 million, net written premiums of $590 million and net earned premiums of $371 million in the first quarter of 2026 compared to gross written premiums of $1,108 million, net written premiums of $690 million and net earned premiums of $346 million in the first quarter of 2025. The decline in Ark’s written premiums was driven primarily by a change in the timing of recognition of certain delegated authority business. This change had no impact on the timing of recognition of Ark’s earned premiums, which increased 7% in the first quarter of 2026 compared to the first quarter of 2025, driven primarily by continued growth in the specialty and property lines of business. Net written premiums were also impacted by Ark’s greater use of quota share reinsurance in the current period. As a result, ceded written premiums increased to $501 million in the first quarter of 2026 from $417 million in the first quarter of 2025. Ark reported pre-tax income of $7 million in the first quarter of 2026 compared to $52 million in the first quarter of 2025. Ark’s results included net realized and unrealized investment gains (losses) of $(33) million in the first quarter of 2026 compared to $30 million in the first quarter of 2025. WM Outrigger Re’s combined ratio was 44% in the first quarter of 2026 compared to 166% in the first quarter of 2025. Catastrophe losses in the first quarter of 2025 included $19 million of losses related to the California wildfires (net of reinstatement premiums). Ark renewed Outrigger Re Ltd. for the 2026 underwriting year with $70 million of unaffiliated third-party capital. Through March 31, 2026, WM Outrigger Re has generated pre-tax income of $57 million from the 2025 underwriting year, $29 million from the 2024 underwriting year and $76 million from the 2023 underwriting year. Kudu reported total revenues of $63 million, pre-tax income of $52 million and adjusted EBITDA of $17 million in the first quarter of 2026 compared to total revenues of $64 million, pre-tax income of $53 million and adjusted EBITDA of $16 million in the first quarter of 2025. Total revenues, pre-tax income and adjusted EBITDA included $21 million of net investment income in the first quarter of 2026 compared to $19 million in the first quarter of 2025. Total revenues and pre-tax income also included $42 million of net realized and unrealized investment gains in the first quarter of 2026 compared to $44 million in the first quarter of 2025. Kudu deployed a total of $21 million, including transaction costs, into one new asset management firm in the first quarter of 2026. As of March 31, 2026, Kudu has deployed $1.2 billion, including transaction costs, into 31 asset and wealth management firms globally, including three that have been exited. As of March 31, 2026, the asset and wealth management firms have combined assets under management (“AUM”) of approximately $155 billion, spanning a range of asset classes. HG Global reported gross written premiums of $8 million and earned premiums of $8 million in the first quarter of 2026 compared to gross written premiums of $7 million and earned premiums of $8 million in the first quarter of 2025. HG Global’s total par value of policies assumed was $518 million in the first quarter of 2026 compared to $427 million in the first quarter of 2025. HG Global’s total gross pricing was 160 basis points in the first quarter of 2026 compared to 157 basis points in the first quarter of 2025. HG Global reported pre-tax income of $11 million in the first quarter of 2026 compared to $25 million in the first quarter of 2025. HG Global’s results included net realized and unrealized investment gains (losses) of $(5) million in the first quarter of 2026 compared to $10 million in the first quarter of 2025, driven by movements in interest rates. The fair value of the BAM Surplus Notes was $346 million as of March 31, 2026 compared to $339 million as of December 31, 2025. The increase was driven by $7 million of accrued interest. Distinguished reported managed premiums of $132 million, commission and fee revenues of $40 million, pre-tax loss of $18 million and ScaleCo adjusted EBITDA of $4 million for the first quarter of 2026. Distinguished’s managed premiums increased by 7% in the first quarter of 2026 compared to the first quarter of 2025. This includes periods prior to White Mountains’s ownership of Distinguished, which White Mountains believe is useful in understanding Distinguished’s performance. As of March 31, 2026, White Mountains owned 17.9 million shares of MediaAlpha, representing a 28% basic ownership interest based on the total class A and class B common shares outstanding. As of March 31, 2026, MediaAlpha’s share price was $9.30 per share, which decreased from $12.95 per share as of December 31, 2025. The carrying value of White Mountains’s investment in MediaAlpha was $166 million as of March 31, 2026 compared to $231 million as of December 31, 2025. At White Mountains’s current level of ownership, each $1.00 per share increase or decrease in the share price of MediaAlpha will result in an approximate $7.00 per share increase or decrease in White Mountains’s book value per share. White Mountains’s total consolidated portfolio return on invested assets was 0.2% in the first quarter of 2026, which included $65 million of unrealized investment losses from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, the total consolidated portfolio return on invested assets was 1.0% in the first quarter of 2026. Excluding MediaAlpha, investment results in the first quarter of 2026 were driven primarily by net investment income, net unrealized investment gains from other long-term investments and net unrealized investment losses from the fixed income and common equity portfolios. White Mountains’s total consolidated portfolio return on invested assets was 1.7% in the first quarter of 2025, which included $37 million of unrealized investment losses from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, the total consolidated portfolio return on invested assets was 2.3% in the first quarter of 2025. Excluding MediaAlpha, investment results in the first quarter of 2025 were driven primarily by net investment income and net unrealized investment gains from the other long-term investments and fixed income portfolios. 48 Book Value Per Share The following table presents White Mountains’s book value per share as of March 31, 2026, December 31, 2025 and March 31, 2025: March 31, 2026 December 31, 2025 March 31, 2025 Book value per share numerator (in millions): White Mountains’s common shareholders’ equity $ 5,373.5 $ 5,425.4 $ 4,509.6 Book value per share denominator (in thousands): Common shares outstanding 2,476.7 2,479.7 2,573. [Excerpt truncated for page length; source filing is linked above.]
Latest 10-K MD&A
Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations The following discussion contains “forward-looking statements.” White Mountains intends statements that are not historical in nature, which are hereby identified as forward-looking statements, to be covered by the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. White Mountains cannot promise that its expectations in such forward-looking statements will turn out to be correct. White Mountains’s actual results could be materially different from and worse than its expectations. See “FORWARD-LOOKING STATEMENTS” on page 101 for specific important factors that could cause actual results to differ materially from those contained in forward-looking statements. The following discussion also includes 12 non-GAAP financial measures: (i) Ark’s tangible book value, (ii) Ark’s tangible capital, (iii) Kudu’s earnings before interest, taxes, depreciation and amortization (“EBITDA”), (iv) Kudu’s adjusted EBITDA, (v) Bamboo’s MGA pre-tax income (loss), (vi) Bamboo’s MGA net income (loss), (vii) Bamboo’s MGA EBITDA, (viii) Bamboo’s MGA adjusted EBITDA, (ix) Distinguished’s ScaleCo net income (loss), (x) Distinguished’s ScaleCo EBITDA, (xi) Distinguished’s ScaleCo adjusted EBITDA and (xii) total consolidated portfolio return excluding MediaAlpha that have been reconciled from their most comparable GAAP financial measures on page 85. White Mountains believes these measures to be useful in evaluating White Mountains’s financial performance and condition. RESULTS OF OPERATIONS FOR THE YEARS ENDED DECEMBER 31, 2025, 2024 AND 2023 Overview—Year Ended December 31, 2025 versus Year Ended December 31, 2024 White Mountains ended 2025 with book value per share of $2,188, an increase of 25% for the year, including dividends. The increase in book value per share was driven primarily by the net gain on sale of the Bamboo Group of approximately $320 per share (based on 2.54 million shares outstanding at December 5, 2025). In addition, the growth in White Mountains’s book value per share reflected solid results at its operating companies and good investment returns. Comprehensive income attributable to common shareholders was $1,109 million in 2025, largely driven by the net gain on sale of the Bamboo Group, compared to $230 million in 2024. White Mountains also recognized a net deferred tax expense of $73 million in 2025 from the reversal of the deferred tax asset related to the Bermuda economic transition adjustment, of which $51 million was recorded at Ark and $22 million was recorded at HG Global. Due to the enactment of Pillar II legislation by Luxembourg in December 2025, White Mountains no longer expects to utilize the benefit of the Bermuda economic transition adjustment. On December 5, 2025, White Mountains completed the sale of a controlling financial interest in the Bamboo Group to affiliates of funds advised by CVC. White Mountains sold approximately 77.3% of its equity interest in the Bamboo Group for net cash proceeds at closing of $848 million and retained an indirect equity interest valued at $250 million. White Mountains’s Other Operations recognized a net gain of $816 million, which was comprised of an $849 million net gain on sale of the Bamboo Group, partially offset by $33 million of parent company compensation costs recorded within general and administrative expenses. On September 2, 2025, White Mountains closed its transaction to acquire a controlling financial interest in Distinguished, a full-service MGA and program administrator for specialty property & casualty insurance. White Mountains paid $225 million of cash consideration, including a post-closing purchase price adjustment of $1 million. In addition, Distinguished borrowed $50 million of incremental debt and utilized $7 million of cash on hand as part of the transaction. On July 18, 2025, White Mountains closed its transaction to deploy $150 million into BroadStreet through the BroadStreet SPV, alongside co-lead investors Ethos Capital LP and British Columbia Investment Management Corporation. BroadStreet is an insurance brokerage company with a presence in all 50 U.S. states and ten Canadian provinces. On April 1, 2025, White Mountains acquired a majority interest in Enterprise Solutions, a provider of specialty electrical contracting services. This was the first acquisition by WTM Partners. White Mountains paid $58 million of cash consideration, and Enterprise Solutions borrowed $15 million in new debt as part of the transaction. In 2025, White Mountains repurchased and retired 100,581 of its common shares for $203 million at an average share price of $2,013.67, or 92% of White Mountains’s December 31, 2025 book value per share. This included 64,064 shares repurchased through the self-tender offer in December. Including a distribution of $128 million from WM Outrigger Re received in January, undeployed capital stands at roughly $1.0 billion. 45 The Ark/WM Outrigger segment’s combined ratio was 81% in 2025 compared to 82% in 2024. The Ark/WM Outrigger segment reported gross written premiums of $2,557 million, net written premiums of $1,812 million and net earned premiums of $1,697 million in 2025 compared to gross written premiums of $2,207 million, net written premiums of $1,679 million and net earned premiums of $1,588 million in 2024. The Ark/WM Outrigger segment reported pre-tax income of $310 million in 2025 compared to $299 million in 2024. Ark’s combined ratio was 83% in both 2025 and 2024. Ark’s combined ratio in 2025 included eight points of catastrophe losses, driven primarily by Hurricane Melissa and losses related to the January 2025 California wildfires, compared to 13 points of catastrophe losses in 2024, driven primarily by Hurricanes Milton, Helene, Debby and Beryl. Ark’s combined ratio included seven points of net favorable prior year development in 2025, driven primarily by property and specialty lines of business. This included six points of unfavorable development related to aviation losses from the conflict in Ukraine and Russia. This compares to four points of net favorable prior year development in 2024, driven primarily by property and specialty lines of business. Ark reported gross written premiums of $2,557 million, net written premiums of $1,727 million and net earned premiums of $1,613 million in 2025 compared to gross written premiums of $2,207 million, net written premiums of $1,593 million and net earned premiums of $1,500 million in 2024. Ark reported pre-tax income of $265 million in 2025 compared to $253 million in 2024. Ark’s results included net realized and unrealized investment gains of $125 million in 2025 compared to $50 million in 2024. Ark’s results in 2025 also included a $173 million of expense related to the increase in fair value of contingent consideration compared to $61 million in 2024. The increase in the contingent consideration liability was driven primarily by strong growth in Ark’s tangible book value in the year. Ark’s results in 2025 also included the reversal of the $51 million deferred tax asset associated with the Bermuda economic transition adjustment. In November 2025, A.M. Best affirmed Ark’s “A/stable” financial strength rating and upgraded its issuer credit rating to “a+/stable”. WM Outrigger Re’s combined ratio was 57% in 2025, compared to 60% in 2024. Catastrophe losses in the year ended December 31, 2025 included $19 million of losses related to the California wildfires (net of reinstatement premiums), primarily attributable to the 2024 underwriting year. WM Outrigger Re reported gross written premiums of $84 million and net earned premiums of $85 million in 2025 compared to gross written premiums of $87 million and net earned premiums of $88 million in 2024. WM Outrigger Re reported pre-tax income (loss) of $45 million in 2025, of which $55 million was attributable to the 2025 underwriting year and $(10) million was attributable to the 2024 underwriting year. WM Outrigger Re reported pre-tax income of $46 million in 2024, of which $38 million was attributable to the 2024 underwriting year and $8 million was attributable to the 2023 underwriting year. Through December 31, 2025, WM Outrigger Re has generated pre-tax income of $55 million from the 2025 underwriting year, $29 million from the 2024 underwriting year and $76 million from the 2023 underwriting year. White Mountains’s capital commitment to WM Outrigger Re was $150 million for the 2025 underwriting year, $130 million for the 2024 underwriting year and $205 million for the 2023 underwriting year. During the fourth quarter of 2025, Ark renewed Outrigger Re Ltd. for the 2026 underwriting year with $70 million of capital. The capital was provided entirely by third-party investors excluding White Mountains. HG Global reported gross written premiums and earned premiums of $61 million and $31 million in 2025 compared to $52 million and $29 million in 2024. HG Global’s total par value of policies assumed was $3,170 million in 2025 compared to $2,952 million in 2024. HG Global’s total gross pricing was 194 basis points in 2025 compared to 177 basis points in 2024. HG Global reported pre-tax income (loss) of $45 million in 2025 compared to $(66) million in 2024. HG Global’s results included net realized and unrealized investment gains (losses) of $23 million in 2025 compared to $(6) million in 2024, driven by movements in interest rates. HG Global’s results in 2025 also included the reversal of the $22 million deferred tax asset associated with the Bermuda economic transition adjustment. HG Global’s results in 2025 included a $38 million decline in the fair value of the BAM surplus notes, which was driven by changes in certain key inputs used in the discounted cash flow analysis. HG Global’s results in 2024 included an increase of $1 million in the fair value of the BAM surplus notes. In addition, HG Global’s results in 2024 included the $115 million unrealized loss on deconsolidation of BAM. The fair value of the BAM Surplus Notes was $339 million as of December 31, 2025 compared to $382 million as of December 31, 2024. The decline was driven by the $38 million decrease in fair value and $35 million in cash payments of principal and interest, partially offset by approximately $30 million of accrued interest. 46 Kudu reported total revenues of $183 million, pre-tax income of $140 million and adjusted EBITDA of $65 million in 2025 compared to total revenues of $119 million, pre-tax income of $81 million and adjusted EBITDA of $55 million in 2024. Total revenues, pre-tax income and adjusted EBITDA included $79 million of net investment income in 2025 compared to $67 million in 2024. Total revenues and pre-tax income also included $104 million of net realized and unrealized investment gains in 2025 compared to $51 million in 2024. Kudu deployed $197 million, including transaction costs, into three new asset management firms in 2025. As of December 31, 2025, Kudu has deployed $1.2 billion, including transaction costs, into 30 asset and wealth management firms globally, including three that have been exited. As of December 31, 2025, the asset and wealth management firms have combined assets under management of approximately $153 billion, spanning a range of asset classes. Bamboo reported commission and fee revenues of $211 million and pre-tax income of $40 million in the period from January 1, 2025 through December 5, 2025, the date of sale, while Bamboo reported commission and fee revenues of $135 million and pre-tax income of $33 million in 2024. Bamboo reported MGA pre-tax income of $41 million and MGA adjusted EBITDA of $91 million in the period from January 1, 2025 through December 5, 2025, while Bamboo reported MGA pre-tax income of $32 million and MGA adjusted EBITDA of $53 million in 2024. Managed premiums, which represent the total premium placed by Bamboo, were $705 million in the period from January 1, 2025 through December 5, 2025 and $484 million in 2024. The increase in managed premiums was driven by growth in the renewal book as well as new business volume. For the period from September 2, 2025, the date of acquisition, through December 31, 2025, Distinguished reported managed premiums of $188 million, commission and fee revenues of $57 million, pre-tax loss of $17 million and ScaleCo adjusted EBITDA of $9 million. As of December 31, 2025, White Mountains owned 17.9 million shares of MediaAlpha, representing a 27.4% basic ownership interest based on the total class A and class B common shares outstanding in MediaAlpha’s Report on Form 10-Q dated October 29, 2025. As of December 31, 2025, MediaAlpha’s share price was $12.95 per share, which increased from $11.29 per share as of December 31, 2024. The carrying value of White Mountains’s investment in MediaAlpha was $231 million as of December 31, 2025, which increased from $202 million as of December 31, 2024. At White Mountains’s current level of ownership, each $1.00 per share increase or decrease in the stock price of MediaAlpha will result in an approximate $7.00 per share increase or decrease in White Mountains’s book value per share. White Mountains’s total consolidated portfolio return on invested assets was 9.1% in 2025, which included $30 million of unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, the total consolidated portfolio return on invested assets was 8.9% in 2025. Excluding MediaAlpha, investment returns in 2025 were driven primarily by net investment income and net unrealized investment gains from other long-term investments, net investment income from the fixed income portfolio and net realized gains from common equity securities. White Mountains’s total consolidated portfolio return on invested assets was 6.9% in 2024, which included $38 million of net realized and unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, the total consolidated portfolio return on invested assets was 6.5% in 2024. Excluding MediaAlpha, investment returns in 2024 were driven primarily by net investment income and net realized and unrealized investment gains from other long-term investments, net investment income from the fixed income portfolio and net unrealized gains from common equity securities. Overview—Year Ended December 31, 2024 versus Year Ended December 31, 2023 White Mountains ended 2024 with book value per share of $1,746, an increase of 6% for the year, including dividends. Comprehensive income attributable to common shareholders was $230 million in 2024 compared to $511 million in 2023. Results in 2024 were driven primarily by solid results from White Mountains’s operating businesses and good returns in the investment portfolio. Results in 2023 were driven primarily by good results from White Mountains’s operating businesses and strong returns in the investment portfolio. White Mountains’s results included net realized and unrealized investment gains of $147 million in 2024 compared to $407 million in 2023. Results in 2024 also included $38 million of net realized and unrealized investment gains from White Mountains’s investment in MediaAlpha compared to $27 million in 2023. As of December 31, 2024, White Mountains’s undeployed capital was approximately $0.7 billion, including the net proceeds received from the debt recapitalization completed in January 2025 at Bamboo. 47 Ark’s combined ratio was 83% in 2024, compared to 82% in 2023. Ark’s combined ratio included 13 points of catastrophe losses in 2024, driven primarily by Hurricanes Milton, Helene, Debby and Beryl, compared to two points of catastrophe losses in 2023, driven primarily by Hurricanes Otis and Idalia as well as the Maui wildfires. The combined ratio in 2024 included four points of net favorable prior year loss reserve development, driven primarily by specialty and property lines of business, compared to two points of net unfavorable prior year loss reserve development in 2023, driven primarily by Hurricane Ian and Winter Storm Elliott. Ark reported gross written premiums of $2,207 million, net written premiums of $1,593 million and net earned premiums of $1,500 million in 2024 compared to gross written premiums of $1,898 million, net written premiums of $1,411 million and net earned premiums of $1,305 million in 2023. Ark reported pre-tax income of $253 million in 2024 compared to $249 million in 2023. Ark’s results in 2023 included a $51 million net deferred tax benefit related to the Bermuda economic transition adjustment. In November 2024, AM Best affirmed Ark’s financial strength rating at “A/stable.” WM Outrigger Re’s combined ratio was 60% in 2024, compared to 44% in 2023. The 2024 combined ratio included catastrophe losses from Hurricanes Milton, Helene, Debby and Beryl. Major catastrophe losses affecting WM Outrigger Re in 2023 were minimal. WM Outrigger Re reported gross and net written premiums of $87 million, net earned premiums of $88 million and pre-tax income of $46 million in 2024, compared to gross and net written premiums of $110 million, net earned premiums of $104 million and pre-tax income of $69 million in 2023. Net earned premiums in 2024 decreased due to White Mountains’s lower capital commitment to WM Outrigger Re in 2024 compared to 2023. During the fourth quarter of 2024, Ark renewed Outrigger Re Ltd. for the 2025 underwriting year. White Mountains’s total commitment toward the 2025 underwriting year is $150 million. As of July 1, 2024, White Mountains no longer consolidates BAM. Upon deconsolidation, the BAM Surplus Notes, including accrued interest receivable, were fair valued in accordance with GAAP at $387 million, which resulted in an unrealized loss on deconsolidation of $115 million. As of December 31, 2024, the BAM Surplus Notes were fair valued at $382 million. The decrease in fair value of $5 million was driven by a $22 million cash payment of principal and interest, partially offset by $16 million of accrued interest and a $1 million increase in fair value as a result of lower market interest rates. HG Global reported gross written premiums and earned premiums of $52 million and $29 million in 2024 compared to $50 million and $26 million in 2023. HG Global reported gross written premiums net of ceding commission paid of $37 million in 2024 compared to $35 million in 2023. HG Global’s total par value of policies assumed, which represents its first-loss exposure on policies assumed from BAM, was $2,952 million in 2024 compared to $2,356 million in 2023. HG Global’s total gross pricing was 177 basis points in 2024 compared to 213 basis points in 2023. Kudu reported total revenues of $119 million, pre-tax income of $81 million and adjusted EBITDA of $55 million in 2024 compared to total revenues of $177 million, pre-tax income of $137 million and adjusted EBITDA of $57 million in 2023. Total revenues and pre-tax income in 2024 included $67 million of net investment income and $51 million of net realized and unrealized investment gains compared to $71 million and $106 million in 2023. Kudu deployed $104 million, including transaction costs, into two new asset management firms in 2024. As of December 31, 2024, Kudu had deployed $989 million, including transaction costs, into 27 asset and wealth management firms globally, including three that have been exited. As of December 31, 2024, the asset and wealth management firms have combined assets under management of approximately $125 billion, spanning a range of asset classes. Bamboo reported commission and fee revenues of $135 million and pre-tax income of $33 million in 2024. Bamboo reported MGA pre-tax income of $32 million and MGA adjusted EBITDA of $53 million in 2024. Managed premiums, which represent the total premium placed by Bamboo, were $484 million in 2024 compared to $215 million in 2023 (prior to White Mountains’s ownership of Bamboo). The increase in managed premiums was driven by growth in new business volume as well as a growing renewal book. 48 On May 10, 2024, MediaAlpha completed a secondary offering of 7.6 million shares at $19.00 per share ($18.24 per share net of underwriting fees). In the secondary offering, White Mountains sold 5.0 million shares for net proceeds of $91 million. As of December 31, 2024, White Mountains owned 17.9 million shares of MediaAlpha, representing a 26.6% basic ownership interest. As of December 31, 2024, MediaAlpha’s share price was $11.29, which increased from $11.15 per share as of December 31, 2023. The carrying value of White Mountains’s investment in MediaAlpha was $202 million as of December 31, 2024, which decreased from $255 million as of December 31, 2023 as a result of the secondary offering. White Mountains’s total consolidated portfolio return on invested assets was 6.9% in 2024, which included $38 million of net realized and unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, the total consolidated portfolio return on invested assets was 6.5% in 2024. Excluding MediaAlpha, investment returns in 2024 were driven primarily by net investment income and net realized and unrealized investment gains from other long-term investments, net investment income from the fixed income portfolio and net unrealized gains from common equity securities. White Mountains’s total consolidated portfolio return on invested assets, both including and excluding White Mountains’s investment in MediaAlpha, was 11.4% in 2023. The total consolidated portfolio return included $27 million of unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, investment returns in 2023 were driven primarily by net investment income and net realized and unrealized investment gains from the other long-term investments and fixed income portfolios. Book Value Per Share The following table presents White Mountains’s book value per share as of December 31, 2025, 2024 and 2023: December 31, 2025 2024 2023 Book value per share numerators (in millions): White Mountains’s common shareholders’ equity $ 5,425.4 $ 4,483.7 $ 4,240.5 Book value per share denominator (in thousands of shares): Common shares outstanding 2,479.7 2,568.1 2,560.5 Book value per share $ 2,187.97 $ 1,745.87 $ 1,656.14 Year-to-date dividends paid per share $ 1.00 $ 1.00 $ 1.00 49 Goodwill and Other Intangible Assets The following table presents goodwill and other intangible assets that are included in White Mountains’s book value as of December 31, 2025, 2024 and 2023: December 31, Millions 2025 2024 2023 Goodwill: Ark $ 116.8 $ 116.8 $ 116.8 Kudu 7.6 7.6 7.6 Bamboo — 270.4 — Distinguished (1) 396.7 — — Other Operations (1) 93.0 44.4 44.4 Total goodwill 614.1 439.2 168.8 Other intangible assets: Ark 175.7 175.7 175.7 Kudu .1 .4 .7 Bamboo — 84.6 — Distinguished (1) 181.0 — — Other Operations (1) 49.3 20.4 25.4 Total other intangible assets 406.1 281.1 201.8 Total goodwill and other intangible assets (2) 1,020.2 720.3 370.6 Total goodwill and other intangible assets attributed to noncontrolling interests (3) (378.6) (190.5) (94.9) Total goodwill and other intangible assets included in White Mountains’s common shareholders’ equity $ 641.6 $ 529.8 $ 275.7 (1) The relative fair values of goodwill and other intangible assets recognized in connection with the Distinguished Transaction and the Enterprise Solutions Transaction have not yet been finalized. See Note 2 — “Significant Transactions” on page F-19. (2) See Note 4 — “Goodwill and Other Intangible Assets” on page F-34 for details of other intangible assets. (3) Amounts reflect the basic ownership percentage of the noncontrolling shareholders. 50 Summary of Consolidated Results The following table presents White Mountains’s consolidated financial results by industry for the years ended December 31, 2025, 2024 and 2023: Year Ended December 31, Millions 2025 2024 2023 Revenues: P&C Insurance and Reinsurance revenues $ 1,943.8 $ 1,750.9 $ 1,557.8 Financial Guarantee revenues 73.6 (44.6) 92.4 Asset Management revenues 183.4 118.8 177.1 P&C Insurance Distribution revenues 246.3 179.8 — Specialty Insurance Distribution revenues 57.7 — — Other Operations revenues 1,230.2 234.9 339.4 Total revenues 3,735.0 2,239.8 2,166.7 Expenses: P&C Insurance and Reinsurance expenses 1,633.6 1,452.1 1,240.3 Financial Guarantee expenses 28.5 60.6 94.0 Asset Management expenses 43.8 37.5 40.6 P&C Insurance Distribution expenses 206.2 147.1 — Specialty Insurance Distribution expenses 74.2 — — Other Operations expenses 420.0 225.8 226.4 Total expenses 2,406.3 1,923.1 1,601.3 Pre-tax income (loss): P&C Insurance and Reinsurance pre-tax income (loss) 310.2 298.8 317.5 Financial Guarantee pre-tax income (loss) 45.1 (105.2) (1.6) Asset Management pre-tax income (loss) 139.6 81.3 136.5 P&C Insurance Distribution pre-tax income (loss) 40.1 32.7 — Specialty Insurance Distribution pre-tax income (loss) (16.5) — — Other Operations pre-tax income (loss) 810.2 9.1 113.0 Total pre-tax income (loss) 1,328.7 316.7 565.4 Net income (loss): Income tax (expense) benefit (126.9) (32.6) 15.5 Net income (loss) 1,201.8 284.1 580.9 Net (income) loss attributable to noncontrolling interests (95.4) (53.7) (71.7) Net income (loss) attributable to White Mountains’s common shareholders 1,106.4 230.4 509.2 Comprehensive income (loss): Other comprehensive income (loss), net of tax 3.7 (.1) 2.4 Comprehensive income (loss) 1,110.1 230.3 511.6 Other comprehensive (income) loss attributable to noncontrolling interests (1.2) — (.5) Comprehensive income (loss) attributable to White Mountains’s common shareholders $ 1,108.9 $ 230.3 $ 511.1 51 I. SUMMARY OF OPERATIONS BY SEGMENT As of December 31, 2025, White Mountains conducted its operations through four reportable segments: (1) Ark/WM Outrigger, (2) HG Global, (3) Kudu and (4) Distinguished, with our remaining operating businesses, holding companies and other assets included in Other Operations. White Mountains has made its segment determination based on consideration of the following criteria: (i) the nature of the business activities of each of the Company’s subsidiaries and affiliates; (ii) the manner in which the Company’s subsidiaries and affiliates are organized; (iii) the existence of primary managers responsible for specific subsidiaries and affiliates; and (iv) the organization of information provided to the Company’s chief operating decision makers and its Board of Directors. Significant intercompany transactions among White Mountains’s segments have been eliminated herein. White Mountains’s segment information is presented in Note 15 — “Segment Information” on page F-70. During the fourth quarter of 2022, Ark sponsored the formation of Outrigger Re Ltd. to provide collateralized reinsurance protection on Ark’s Bermuda global property catastrophe excess of loss portfolio written in the 2023 underwriting year. Ark renewed its quota share reinsurance agreement with Outrigger Re Ltd. for the 2024, 2025 and 2026 underwriting years. White Mountains consolidates its segregated account of Outrigger Re Ltd., WM Outrigger Re, in its financial statements. WM Outrigger Re’s quota share reinsurance agreement with GAIL eliminates in White Mountains’s consolidated financial statements. WM Outrigger Re exclusively provides reinsurance protection to Ark. As a result, WM Outrigger Re was aggregated with Ark within the Ark/WM Outrigger segment starting in 2023. See Note 2 — “Significant Transactions” on page F-19. Effective July 1, 2024, White Mountains no longer consolidates BAM. Through June 30, 2024, BAM’s results of operations, are presented within the HG Global segment. See Note 2 — “Significant Transactions” on page F-19. On December 5, 2025, White Mountains completed the Bamboo Sale Transaction. As a result, White Mountains deconsolidated the Bamboo Group on December 5, 2025, and Bamboo is no longer a reportable segment. Through December 5, 2025, Bamboo’s results of operations, are presented within the Bamboo segment. White Mountains’s noncontrolling equity interest in the Bamboo SPV is accounted for at fair value in other long-term investments within Other Operations. See Note 2 — “Significant Transactions” on page F-19. On September 2, 2025, White Mountains completed the Distinguished Transaction. As a result, White Mountains began consolidating Distinguished in its financial statements on September 2, 2025. See Note 2 — “Significant Transactions” on page F-19. A discussion of White Mountains’s consolidated investment operations is included after the discussion of operations by segment. Ark/WM Outrigger Ark is a specialty property and casualty insurance and reinsurance company that offers a wide range of niche insurance and reinsurance products, including property, specialty, marine & energy, casualty and accident & health. Ark underwrites select coverages through its two major subsidiaries in the United Kingdom and Bermuda. Ark sponsored the formation of Outrigger Re Ltd., a Bermuda company registered as a special purpose insurer and segregated accounts company, to provide collateralized reinsurance protection on Ark’s Bermuda global property catastrophe excess of loss portfolio. White Mountains consolidates its segregated account of Outrigger Re Ltd., WM Outrigger Re, in its financial statements. 52 The following tables present the components of pre-tax income (loss) included in the Ark/WM Outrigger segment for the years ended December 31, 2025, 2024 and 2023: Year Ended December 31, 2025 Millions Ark WM Outrigger Re Eliminations Total Direct written premiums $ 1,260.1 $ — $ — $ 1,260.1 Assumed written premiums 1,297.1 84.2 (84.2) 1,297.1 Gross written premiums 2,557.2 84.2 (84.2) 2,557.2 Ceded written premiums (829.8) — 84.2 (745.6) Net written premiums $ 1,727.4 $ 84.2 $ — $ 1,811.6 Earned insurance premiums $ 1,612.8 $ 84.6 $ — $ 1,697.4 Net investment income 97.4 9.1 — 106.5 Net realized and unrealized investment gains (losses) 124.6 — — 124.6 Other revenues 15.3 — — 15.3 Total revenues 1,850.1 93.7 — 1,943.8 Loss and LAE 818.8 25.4 — 844.2 Acquisition expenses 371.1 23.1 — 394.2 General and administrative expenses - other underwriting 143.9 — — 143.9 General and administrative expenses - all other 61.1 .1 — 61.2 Change in fair value of contingent consideration 173.0 — — 173.0 Interest expense 17.1 — — 17.1 Total expenses 1,585.0 48.6 — 1,633.6 Pre-tax income (loss) $ 265.1 $ 45.1 $ — $ 310.2 Year Ended December 31, 2024 Millions Ark WM Outrigger Re Eliminations Total Direct written premiums $ 1,101.5 $ — $ — $ 1,101.5 Assumed written premiums 1,105.5 86.5 (86.5) 1,105.5 Gross written premiums 2,207.0 86.5 (86.5) 2,207.0 Ceded written premiums (614.4) — 86.5 (527.9) Net written premiums $ 1,592.6 $ 86.5 $ — $ 1,679.1 Earned insurance premiums $ 1,499.8 $ 88.0 $ — $ 1,587.8 Net investment income 79.4 11.3 — 90.7 Net realized and unrealized investment gains (losses) 50.1 — — 50.1 Other revenues 22.3 — — 22.3 Total revenues 1,651.6 99.3 — 1,750.9 Loss and LAE 825.9 29.9 — 855.8 Acquisition expenses 283.9 23.2 — 307.1 General and administrative expenses - other underwriting 136.1 — — 136.1 General and administrative expenses - all other 72.2 .1 — 72.3 Change in fair value of contingent consideration 61.3 — — 61.3 Interest expense 19.5 — — 19.5 Total expenses 1,398.9 53.2 — 1,452.1 Pre-tax income (loss) $ 252.7 $ 46.1 $ — $ 298.8 53 Year Ended December 31, 2023 Millions Ark WM Outrigger Re Eliminations Total Direct written premiums $ 931.9 $ — $ — $ 931.9 Assumed written premiums 966.5 110.0 (110.0) 966.5 Gross written premiums 1,898.4 110.0 (110.0) 1,898.4 Ceded written premiums (487.5) — 110.0 (377.5) Net written premiums $ 1,410.9 $ 110.0 $ — $ 1,520.9 Earned insurance premiums $ 1,305.4 $ 104.3 $ — $ 1,409.7 Net investment income 50.4 11.0 — 61.4 Net realized and unrealized investment gains (losses) 85.9 — — 85.9 Other revenues .8 — — .8 Total revenues 1,442.5 115.3 — 1,557.8 Loss and LAE 711.2 15.6 — 726.8 Acquisition expenses 251.0 30.5 — 281.5 General and administrative expenses - other underwriting 113.6 — — 113.6 General and administrative expenses - all other 48.1 .3 — 48.4 Change in fair value of contingent consideration 48.7 — — 48.7 Interest expense 21.3 — — 21.3 Total expenses 1,193.9 46.4 — 1,240.3 Pre-tax income (loss) $ 248.6 $ 68.9 $ — $ 317.5 Combined Ratio The following tables present the Ark/WM Outrigger segment’s insurance premiums, insurance expenses and insurance ratios for the years ended December 31, 2025, 2024 and 2023: Year Ended December 31, 2025 $ in Millions Ark WM Outrigger Re Eliminations Total Insurance premiums: Gross written premiums $ 2,557.2 $ 84.2 $ (84.2) $ 2,557.2 Net written premiums $ 1,727.4 $ 84.2 $ — $ 1,811.6 Net earned premiums $ 1,612.8 $ 84.6 $ — $ 1,697.4 Insurance expenses: Loss and LAE $ 818.8 $ 25.4 $ — $ 844.2 Acquisition expenses 371.1 23.1 — 394.2 Other underwriting expenses (1) 143.9 — — 143.9 Total insurance expenses $ 1,333.8 $ 48.5 $ — $ 1,382.3 Insurance ratios: Loss and LAE 50.8 % 30.0 % — % 49.7 % Acquisition expense 23.0 27.3 — 23.2 Other underwriting expense 8.9 — — 8.5 Combined Ratio 82.7 % 57.3 % — % 81.4 % (1) Included within general and administrative expenses in the consolidated statement of operations. 54 Year Ended December 31, 2024 $ in Millions Ark WM Outrigger Re Eliminations Total Insurance premiums: Gross written premiums $ 2,207.0 $ 86.5 $ (86.5) $ 2,207.0 Net written premiums $ 1,592.6 $ 86.5 $ — $ 1,679.1 Net earned premiums $ 1,499.8 $ 88.0 $ — $ 1,587.8 Insurance expenses: Loss and LAE $ 825.9 $ 29.9 $ — $ 855.8 Acquisition expenses 283.9 23.2 — 307.1 Other underwriting expenses (1) 136.1 — — 136.1 Total insurance expenses $ 1,245.9 $ 53.1 $ — $ 1,299.0 Insurance ratios: Loss and LAE 55.1 % 34.0 % — % 53.9 % Acquisition expense 18.9 26.3 — 19.3 Other underwriting expense 9.1 — — 8.6 Combined Ratio 83.1 % 60.3 % — % 81.8 % (1) Included within general and administrative expenses in the consolidated statement of operations. Year Ended December 31, 2023 $ in Millions Ark WM Outrigger Re Eliminations Total Insurance premiums: Gross written premiums $ 1,898.4 $ 110.0 $ (110.0) $ 1,898.4 Net written premiums $ 1,410.9 $ 110.0 $ — $ 1,520.9 Net earned premiums $ 1,305.4 $ 104.3 $ — $ 1,409.7 Insurance expenses: Loss and LAE $ 711.2 $ 15.6 $ — $ 726.8 Acquisition expenses 251.0 30.5 — 281.5 Other underwriting expenses (1) 113.6 — — 113.6 Total insurance expenses $ 1,075.8 $ 46.1 $ — $ 1,121.9 Insurance ratios: Loss and LAE 54.5 % 15.0 % — % 51.6 % Acquisition expense 19.2 29.2 — 20.0 Other underwriting expense 8.7 — — 8.0 Combined Ratio 82.4 % 44.2 % — % 79.6 % (1) Included within general and administrative expenses in the consolidated statement of operations. 55 The following table presents WM Outrigger Re’s insurance premiums, combined ratio and pre-tax income by underwriting year for the years ended December 31, 2025, 2024 and 2023: Year Ended December 31, 2025 $ in Millions 2025 Underwriting Year 2024 Underwriting Year 2023 Underwriting Year Total Insurance premiums: Gross written premiums $ 82.8 $ 1.4 $ — $ 84.2 Net written premiums $ 82.8 $ 1.4 $ — $ 84.2 Net earned premiums $ 78.9 $ 5.7 $ — $ 84.6 Combined Ratio 42.2 % 266.5 % — % 57.3 % Pre-tax income $ 54.7 $ (9.6) $ — $ 45.1 Year Ended December 31, 2024 2023 $ in Millions 2024 Underwriting Year 2023 Underwriting Year Total 2023 Underwriting Year Insurance premiums: Gross written premiums $ 87.3 $ (.8) $ 86.5 $ 110.0 Net written premiums $ 87.3 $ (.8) $ 86.5 $ 110.0 Net earned premiums $ 83.0 $ 5.0 $ 88.0 $ 104.3 Combined Ratio 67.2 % (53.8) % 60.3 % 44.2 % Pre-tax income $ 38.5 $ 7.6 $ 46.1 $ 68.9 Through December 31, 2025, WM Outrigger Re has generated pre-tax income of $55 million from the 2025 underwriting year, $29 million from the 2024 underwriting year and $76 million from the 2023 underwriting year. White Mountains’s capital commitment to WM Outrigger Re was $150 million for the 2025 underwriting year, $130 million for the 2024 underwriting year and $205 million for the 2023 underwriting year. During the fourth quarter of 2025, Ark renewed Outrigger Re Ltd. for the 2026 underwriting year with $70 million of capital. The reduced capacity at Outrigger Re Ltd. was replaced by Ark through traditional quota share reinsurance agreements. The capital was provided entirely by third-party investors excluding White Mountains. 56 Ark/WM Outrigger Results—Year Ended December 31, 2025 versus Year Ended December 31, 2024 Ark/WM Outrigger segment’s combined ratio was 81% in 2025, compared to 82% in 2024. The Ark/WM Outrigger segment reported gross written premiums of $2,557 million, net written premiums of $1,812 million and net earned premiums of $1,697 million in 2025, compared to gross written premiums of $2,207 million, net written premiums of $1,679 million and net earned premiums of $1,588 million in 2024. The Ark/WM Outrigger segment reported pre-tax income of $310 million in 2025 compared to $299 million in 2024. Ark’s combined ratio was 83% in both 2025 and 2024. Ark’s combined ratio included eight points of catastrophe losses in 2025, driven primarily by Hurricane Melissa as well as losses related to the January 2025 California wildfires of $78 million on a net basis after reinsurance and reinstatement premiums, compared to 13 points of catastrophe losses in 2024, driven primarily by Hurricanes Milton, Helene, Debby and Beryl. Ark’s combined ratio included seven points of net favorable prior year development in 2025, driven primarily by property and specialty lines of business. This included six points of unfavorable development related to aviation losses from the conflict in Ukraine and Russia. This compares to four points of net favorable prior year development in 2024, driven primarily by property and specialty lines of business. Ark reported gross written premiums of $2,557 million, net written premiums of $1,727 million and net earned premiums of $1,613 million in 2025, compared to gross written premiums of $2,207 million, net written premiums of $1,593 million and net earned premiums of $1,500 million in 2024. The increase in gross written premiums was driven primarily by the addition of new underwriting teams and classes of business in the property and specialty lines of business. Ark reported pre-tax income of $265 million in 2025 compared to $253 million in 2024. Ark’s results included net realized and unrealized investment gains of $125 million in 2025, driven primarily by net unrealized investment gains on other long-term investments and common equity securities and net foreign currency gains, compared to $50 million in 2024, driven primarily by net unrealized investment gains on other long-term investments and common equity securities, partially offset by net foreign currency losses. Ark’s results in 2025 also included a $173 million increase in the fair value of contingent consideration compared to $61 million in 2024. The increase in the contingent consideration liability was driven primarily by strong growth in Ark’s tangible book value in the year. See “Contingent Consideration Liabilities” in Note 1 — “Basis of Presentation and Significant Accounting Policies” on page F-18. Ark’s results in 2025 also included the reversal of the $51 million deferred tax asset associated with the Bermuda economic transition adjustment. WM Outrigger Re’s combined ratio was 57% in 2025, compared to 60% in 2024. Catastrophe losses in 2025 included $19 million of losses related to the California wildfires, net of reinstatement premiums. WM Outrigger Re’s losses related to the California wildfires were $2 million for the 2025 underwriting year and $17 million for the 2024 underwriting year. Catastrophe losses in 2024 included Hurricanes Milton, Helene, Debby and Beryl. In 2025, WM Outrigger Re’s combined ratio was 42% for the 2025 underwriting year and 267% for the 2024 underwriting year. In 2024, WM Outrigger Re’s combined ratio was 67% for the 2024 underwriting year and (54)% for the 2023 underwriting year. WM Outrigger Re reported gross written premiums of $84 million and net earned premiums of $85 million in 2025, compared to gross written premiums of $87 million and net earned premiums of $88 million in 2024. WM Outrigger Re reported pre-tax income (loss) of $45 million in 2025, of which $55 million related to the 2025 underwriting year and $(10) million related to the 2024 underwriting year. WM Outrigger Re reported pre-tax income of $46 million in 2024, of which $38 million related to the 2024 underwriting year and $8 million related to the 2023 underwriting year. Ark/WM Outrigger Results—Year Ended December 31, 2024 versus Year Ended December 31, 2023 Ark/WM Outrigger segment’s combined ratio was 82% in 2024, compared to 80% in 2023. The Ark/WM Outrigger segment reported gross written premiums of $2,207 million, net written premiums of $1,679 million and net earned premiums of $1,588 million in 2024, compared to gross written premiums of $1,898 million, net written premiums of $1,521 million and net earned premiums of $1,410 million in 2023. The Ark/WM Outrigger segment reported pre-tax income of $299 million in 2024 compared to $318 million in 2023. Ark’s combined ratio was 83% in 2024 compared to 82% in 2023. Ark’s combined ratio included 13 points of catastrophe losses in 2024, driven primarily by Hurricanes Milton, Helene, Debby and Beryl, compared to two points of catastrophe losses in 2023, driven primarily by Hurricanes Otis and Idalia as well as the Maui wildfires. Ark’s combined ratio included four points of net favorable prior year development in 2024, driven primarily by specialty and property lines of business, compared to two points of net unfavorable prior year development in 2023, driven primarily by Hurricane Ian and Winter Storm Elliott, partially offset by net favorable prior year loss reserve development within the specialty and casualty–runoff reserving lines of business. Ark reported gross written premiums of $2,207 million, net written premiums of $1,593 million and net earned premiums of $1,500 million in 2024, compared to gross written premiums of $1,898 million, net written premiums of $1,411 million and net earned premiums of $1,305 million in 2023. 57 Ark reported pre-tax income of $253 million in 2024 compared to $249 million in 2023. Ark’s results included net realized and unrealized investment gains (losses) of $50 million in 2024, driven primarily by net unrealized investment gains on other long-term investments and common equity securities, partially offset by net foreign currency losses, compared to $86 million in 2023, driven primarily by net unrealized investment gains on other long-term investments, fixed maturity investments and common equity securities. Ark’s results in 2024 also included a $61 million increase in the fair value of contingent consideration compared to $49 million in 2023. Ark’s results in 2023 included a $51 million net deferred tax benefit related to the Bermuda economic transition adjustment. WM Outrigger Re’s combined ratio was 60% in 2024, compared to 44% in 2023. The 2024 combined ratio included catastrophe losses from Hurricanes Milton, Helene, Debby and Beryl. Major catastrophe losses affecting WM Outrigger Re in 2023 were minimal. WM Outrigger Re reported gross written premiums of $87 million and net earned premiums of $88 million in 2024, compared to gross written premiums of $110 million and net earned premiums of $104 million in 2023. Net earned premiums in 2024 decreased due to White Mountains’s lower capital commitment to WM Outrigger Re in 2024 compared to 2023. WM Outrigger Re reported pre-tax income of $46 million in 2024, compared to pre-tax income of $69 million in 2023. Gross Written Premiums Ark’s gross written premiums increased 16% to $2,557 million in 2025 compared to $2,207 million in 2024, with risk adjusted rate change of -4%. The increase in gross written premiums was driven primarily by the addition of new underwriting teams and classes of business in the property and specialty lines of business. The risk adjusted rate change on the Outrigger Re Ltd. portfolio of global property reinsurance was -5% in 2025. Ark’s gross written premiums increased 16% to $2,207 million in 2024 compared to $1,898 million in 2023, with flat risk adjusted rate change. The increase in gross written premiums was across all lines of business but driven primarily by structured property transactions placed in Bermuda and the addition of new products and underwriting teams, including accident & health, marine liability and political violence. The risk adjusted rate change on the Outrigger Re Ltd. portfolio of global property reinsurance was -3% in 2024. The following table presents Ark’s gross written premiums by line of business for the years ended December 31, 2025, 2024 and 2023: Year Ended December 31, Millions 2025 2024 2023 Property $ 1,178.0 $ 1,080.8 $ 917.0 Specialty 646.7 450.0 436.6 Marine & Energy 453.6 449.6 375.7 Casualty 168.8 130.6 98.7 Accident & Health 110.1 96.0 70.4 Total Gross Written Premium $ 2,557.2 $ 2,207.0 $ 1,898.4 58 Ark/WM Outrigger Balance Sheets The following tables present amounts from Ark and WM Outrigger Re that are contained within White Mountains’s consolidated balance sheet as of December 31, 2025 and 2024: December 31, 2025 Millions Ark WM Outrigger Re Eliminations and Segment Adjustments Total Assets Fixed maturity investments, at fair value $ 1,917.9 $ — $ — $ 1,917.9 Common equity securities, at fair value 452.3 — — 452.3 Short-term investments, at fair value 620.9 245.7 — 866.6 Other long-term investments 689.7 — — 689.7 Total investments 3,680.8 245.7 — 3,926.5 Cash 104.7 .1 — 104.8 Reinsurance recoverables 874.7 — (38.6) 836.1 Insurance premiums receivable 848.4 23.9 (23.9) 848.4 Deferred acquisition costs 210.4 .7 — 211.1 Goodwill and other intangible assets 292.5 — — 292.5 Other assets 134.7 — — 134.7 Total assets $ 6,146.2 $ 270.4 $ (62.5) $ 6,354.1 Liabilities Loss and LAE $ 2,481.0 $ 34.7 $ (34.7) $ 2,481.0 Unearned insurance premiums 1,026.1 3.9 (3.9) 1,026.1 Debt 159.7 — — 159.7 Reinsurance payable 310.1 — (23.9) 286.2 Contingent consideration 328.3 — — 328.3 Other liabilities 247.1 .1 — 247.2 Total liabilities 4,552.3 38.7 (62.5) 4,528.5 Equity White Mountains’s common shareholders’ equity 1,128.7 231.7 — 1,360.4 Noncontrolling interests 465.2 — — 465.2 Total equity 1,593.9 231.7 — 1,825.6 Total liabilities and equity $ 6,146.2 $ 270.4 $ (62.5) $ 6,354.1 Tangible book value and tangible capital: Total equity $ 1,593.9 $ 231.7 $ — $ 1,825.6 Less: goodwill and other intangible assets, net (1) (248.6) — — (248.6) Plus: contingent consideration 328.3 — — 328.3 Total tangible book value (2) 1,673.6 231.7 — 1,905.3 Debt 159.7 — — 159.7 Total tangible capital (2) $ 1,833.3 $ 231.7 $ — $ 2,065.0 (1) Amount is net of $43.9 in deferred tax liabilities related to the intangible assets. (2) See “NON-GAAP FINANCIAL MEASURES” on page 85. 59 December 31, 2024 Millions Ark WM Outrigger Re Eliminations and Segment Adjustments Total Assets Fixed maturity investments, at fair value $ 1,565.1 $ — $ — $ 1,565.1 Common equity securities, at fair value 425.4 — — 425.4 Short-term investments, at fair value 397.7 203.7 — 601.4 Other long-term investments 547.8 — — 547.8 Total investments 2,936.0 203.7 — 3,139.7 Cash 141.1 .1 — 141.2 Reinsurance recoverables 628.2 — (39.2) 589.0 Insurance premiums receivable 768.6 30.9 (30.9) 768.6 Deferred acquisition costs 164.4 .8 — 165.2 Goodwill and other intangible assets 292.5 — — 292.5 Other assets 202.8 — — 202.8 Total assets $ 5,133.6 $ 235.5 $ (70.1) $ 5,299.0 Liabilities Loss and LAE $ 2,127.5 $ 34.9 $ (34.9) $ 2,127.5 Unearned insurance premiums 853.3 4.3 (4.3) 853.3 Debt 154.5 — — 154.5 Reinsurance payable 180.4 — (30.9) 149.5 Contingent consideration 155.3 — — 155.3 Other liabilities 224.7 — — 224.7 Total liabilities 3,695.7 39.2 (70.1) 3,664.8 Equity White Mountains’s common shareholders’ equity 1,027.5 196.3 — 1,223.8 Noncontrolling interests 410.4 — — 410.4 Total equity 1,437.9 196.3 — 1,634.2 Total liabilities and equity $ 5,133.6 $ 235.5 $ (70.1) $ 5,299.0 Tangible book value and tangible capital: Total equity $ 1,437.9 $ 196.3 $ — $ 1,634.2 Less: goodwill and other intangible assets, net (1) (248.6) — — (248.6) Plus: contingent consideration 155.3 — — 155.3 Total tangible book value (2) 1,344.6 196.3 — 1,540.9 Debt 154.5 — — 154.5 Total tangible capital (2) $ 1,499.1 $ 196.3 $ — $ 1,695.4 (1) Amount is net of $43.9 in deferred tax liabilities related to the intangible assets. (2) See “NON-GAAP FINANCIAL MEASURES” on page 85. 60 HG Global HG Global was established to fund the startup of BAM and, through its reinsurance subsidiary HG Re, to provide up to 15%-of-par, first-loss reinsurance protection for policies underwritten by BAM. The following tables present the components of pre-tax income (loss) included in the HG Global segment for the years ended December 31, 2025, 2024 and 2023. The HG Global segment consists of HG Global, which includes HG Re and its other wholly-owned subsidiaries, and, prior to its deconsolidation on July 1, 2024, BAM. Through June 30, 2024, BAM’s results of operations are presented within the HG Global segment. December 31, 2025 Millions Direct written premiums $ — Assumed written premiums 61.4 Gross written premiums 61.4 Ceded written premiums — Net written premiums $ 61.4 Earned insurance premiums $ 30.8 Net investment income 27.1 Net realized and unrealized investment gains (losses) 23.2 Interest income from BAM Surplus Notes 29.8 Change in fair value of BAM Surplus Notes (37.5) Other revenues (1) 1.0 Total revenues 74.4 Acquisition expenses 8.0 General and administrative expenses 3.1 Interest expense 17.4 Total expenses 28.5 Pre-tax income (loss) $ 45.9 (1) Amount includes $0.8 of intercompany revenues that are eliminated in White Mountains’s consolidated financial statements. For segment reporting, HG Global’s intercompany revenues included within the HG Global segment are eliminated against the offsetting intercompany expense included within Other Operations. 61 December 31, 2024 Millions HG Global BAM (1) Eliminations Total Direct written premiums $ — $ 24.1 $ — $ 24.1 Assumed written premiums 52.4 — (20.5) 31.9 Gross written premiums 52.4 24.1 (20.5) 56.0 Ceded written premiums — (20.5) 20.5 — Net written premiums $ 52.4 $ 3.6 $ — $ 56.0 Earned insurance premiums $ 28.9 $ 2.8 $ — $ 31.7 Net investment income 23.4 8.8 — 32.2 Net realized and unrealized investment gains (losses) (6.4) (5.1) — (11.5) Interest income from BAM Surplus Notes 29.0 — (13.2) 15.8 Change in fair value of BAM Surplus Notes .5 — — .5 Unrealized loss on deconsolidation of BAM (2) (114.5) — — (114.5) Other revenues (3) .6 1.1 — 1.7 Total revenues (38.5) 7.6 (13.2) (44.1) Acquisition expenses 7.8 .4 — 8.2 General and administrative expenses 2.2 33.5 — 35.7 Interest expense (4) 17.7 — — 17.7 Interest expense from BAM Surplus Notes — 13.2 (13.2) — Total expenses 27.7 47.1 (13.2) 61.6 Pre-tax income (loss) $ (66.2) $ (39.5) $ — $ (105.7) Supplemental information: MSC collected (5) $ — $ 26.0 $ — $ 26.0 (1) Effective July 1, 2024, White Mountains no longer consolidates BAM. For the period from January 1, 2024 through June 30, 2024, BAM’s results of operations were presented within the HG Global segment. (2) Upon the deconsolidation of BAM, the BAM Surplus Notes, including accrued interest receivable, were fair valued in accordance with GAAP at $387.4, which resulted in an unrealized loss on deconsolidation of $114.5. (3) Amount includes $0.5 of intercompany revenues that are eliminated in White Mountains’s consolidated financial statements. For segment reporting, HG Global’s intercompany revenues included within the HG Global segment are eliminated against the offsetting intercompany expense included within Other Operations (4) Amount includes $1.0 of intercompany interest expense that is eliminated in White Mountains’s consolidated financial statements. For segment reporting, HG Global’s intercompany interest expense included within the HG Global segment is eliminated against the offsetting intercompany interest income included within Other Operations. (5) MSC collected are recorded directly to BAM’s equity, which was recorded as noncontrolling interests on White Mountains’s balance sheet through June 30, 2024. 62 December 31, 2023 Millions HG Global BAM Eliminations Total Direct written premiums $ — $ 58.6 $ — $ 58.6 Assumed written premiums 50.1 — (50.1) — Gross written premiums 50.1 58.6 (50.1) 58.6 Ceded written premiums — (50.1) 50.1 — Net written premiums $ 50.1 $ 8.5 $ — $ 58.6 Earned insurance premiums $ 26.0 $ 5.2 $ — $ 31.2 Net investment income 17.1 14.6 — 31.7 Net realized and unrealized investment gains (losses) 13.6 13.0 — 26.6 Interest income from BAM Surplus Notes 26.2 — (26.2) — Other revenues — 2.9 — 2.9 Total revenues 82.9 35.7 (26.2) 92.4 Acquisition expenses 7.4 1.2 — 8.6 General and administrative expenses 2.8 66.1 — 68.9 Interest expense (1) 17.0 — — 17.0 Interest expense from BAM Surplus Notes — 26.2 (26.2) — Total expenses 27.2 93.5 (26.2) 94.5 Pre-tax income (loss) $ 55.7 $ (57.8) $ — $ (2.1) Supplemental information: MSC collected (2) $ — $ 72.8 $ — $ 72.8 (1) Amount includes $0.5 of intercompany interest expense that is eliminated in White Mountains’s consolidated financial statements. For segment reporting, HG Global’s intercompany interest expense included within the HG Global segment is eliminated against the offsetting intercompany interest income included within Other Operations. (2) MSC collected are recorded directly to BAM’s equity, which is recorded as noncontrolling interests on White Mountains’s balance sheet. HG Global Results—Year Ended December 31, 2025 versus Year Ended December 31, 2024 HG Global reported gross written premiums of $61 million and earned premiums of $31 million in 2025 compared to gross written premiums of $52 million and earned premiums of $29 million in 2024. HG Global reported gross written premiums net of ceding commission paid of $43 million in 2025 compared to $37 million in 2024. HG Global’s total par value of policies assumed, which represents its first-loss exposure on policies assumed from BAM, was $3,170 million in 2025, of which $2,718 million was in the primary market and $452 million in the secondary market, compared to $2,952 million in 2024, of which $2,614 million was in the primary market and $338 million in the secondary market. The increase in primary market par assumed was driven by increased municipal bond issuance. The increase in secondary market par assumed was driven by increased uncertainty in financial markets, which created more demand for bond insurance. HG Global’s total gross pricing was 194 basis points in 2025, compared to 177 basis points in 2024. Pricing in the primary market increased to 160 basis points in 2025 compared to 140 basis points in 2024, due to an increase in the volume of large, higher-priced issuances insured by BAM in 2025. Pricing in the secondary market, which is more transaction specific than pricing in the primary market, decreased to 398 basis points in 2025 compared to 464 basis points in 2024, due to a decrease in the volume and pricing of larger secondary market issuances insured by BAM in 2025. Total pricing net of ceding commission paid increased to 136 basis points in 2025 compared to 125 basis points in 2024. 63 The following table presents HG Global’s par value assumed, reinsurance premiums and pricing for the years ended December 31, 2025 and 2024: Year Ended December 31, $ in Millions 2025 2024 Par value assumed: Par value of primary market policies assumed (1) $ 2,718.2 $ 2,614.0 Par value of secondary market policies assumed (1) 451.8 338.4 Total par value of policies assumed $ 3,170.0 $ 2,952.4 Reinsurance premiums: Gross written premiums from primary market $ 43.4 $ 36.7 Gross written premiums from secondary market 18.0 15.7 Total gross written premiums 61.4 52.4 Ceding commission paid 18.3 15.4 Total gross written premiums net of ceding commission paid $ 43.1 $ 37.0 Earned premiums $ 30.8 $ 28.9 Pricing: Gross pricing from primary market 160 bps 140 bps Gross pricing from secondary market 398 bps 464 bps Total gross pricing 194 bps 177 bps Total pricing net of ceding commission paid 136 bps 125 bps (1) For capital appreciation bonds, par is adjusted to the estimated equivalent par value for current interest paying bonds. HG Global reported pre-tax income (loss) of $46 million in 2025 compared to $(66) million in 2024. HG Global’s results included net realized and unrealized investment gains (losses) on its fixed income portfolio of $23 million in 2025 compared to $(6) million in 2024, driven by movements in interest rates. HG Global’s results included interest income on the BAM Surplus Notes of $30 million in 2025 compared to $29 million in 2024. HG Global’s results in 2025 included a $38 million decline in the fair value of the BAM surplus notes, which was driven by changes in certain key inputs used in the discounted cash flow analysis. HG Global’s results in 2024 included an increase $1 million in the fair value of the BAM surplus notes. In addition, HG Global’s results in 2024 included the $115 million unrealized loss on deconsolidation of BAM. See Note 10 — “Municipal Bond Guarantee Insurance - BAM Surplus Notes” on page F-61. HG Global’s results in 2025 also included the reversal of the $22 million deferred tax asset associated with the Bermuda economic transition adjustment. During 2025, HG Global received cash payments of principal and interest on the BAM Surplus Notes totaling $35 million. Of these payments, $24 million was a repayment of principal held in the Supplemental Trust, less than $1 million was a payment of accrued interest held in the Supplemental Trust and $11 million was a payment of accrued interest held outside the Supplemental Trust. During 2024, HG Global received cash payments of principal and interest on the BAM Surplus Notes totaling $30 million. Of these payments, $21 million was a repayment of principal held in the Supplemental Trust, $1 million was a payment of accrued interest held in the Supplemental Trust and $8 million was a payment of accrued interest held outside the Supplemental Trust. During 2025, HG Re received a distribution from the Supplemental Trust of $61 million, which consisted of an assignment of accrued interest on the BAM Surplus Notes of $30 million and a cash distribution of $31 million. During 2024, HG Re received a distribution from the Supplemental Trust of $80 million, which consisted of an assignment of accrued interest on the BAM Surplus Notes of $59 million and a cash distribution of $21 million. 64 HG Global Results—Year Ended December 31, 2024 versus Year Ended December 31, 2023 Effective July 1, 2024, White Mountains no longer consolidates BAM. Upon deconsolidation, the BAM Surplus Notes, including accrued interest receivable, were fair valued in accordance with GAAP at $387 million, which resulted in an unrealized loss on deconsolidation of $115 million. As of December 31, 2024, the BAM Surplus Notes were fair valued at $382 million. The decrease in fair value of $5 million was driven by a $22 million cash payment of principal and interest, partially offset by $16 million of accrued interest and a $1 million increase in fair value as a result of lower market interest rates. HG Global reported gross written premiums of $52 million and earned premiums of $29 million in 2024 compared to gross written premiums of $50 million and earned premiums of $26 million in 2023. HG Global reported gross written premiums net of ceding commission paid of $37 million in 2024 compared to $35 million in 2023. HG Global’s total par value of policies assumed, which represents its first-loss exposure on policies assumed from BAM, was $2,952 million in 2024, of which $2,614 million was in the primary market and $338 million in the secondary market, compared to $2,356 million in 2023, of which $1,930 million was in the primary market and $426 million in the secondary market. HG Global’s total gross pricing was 177 basis points in 2024 compared to 213 basis points in 2023. Pricing in the primary market decreased to 140 basis points in 2024 compared to 164 basis points in 2023, due to tighter municipal bond spreads and an increase in the volume of large, higher-credit issuances insured by BAM. Pricing in the secondary market, which is more transaction specific than pricing in the primary market, increased to 464 basis points in 2024 compared to 434 basis points in 2023. Total pricing net of ceding commission paid decreased to 125 basis points in 2024 compared to 148 basis points in 2023. The following table presents HG Global’s par value assumed, reinsurance premiums and pricing for the years ended December 31, 2024 and 2023: Year Ended December 31, $ in Millions 2024 2023 Par value assumed: Par value of primary market policies assumed (1) $ 2,614.0 $ 1,929.9 Par value of secondary market policies assumed (1) 338.4 426.4 Total par value of policies assumed $ 2,952.4 $ 2,356.3 Reinsurance premiums: Gross written premiums from primary market $ 36.7 $ 31.6 Gross written premiums from secondary market 15.7 18.5 Total gross written premiums 52.4 50.1 Ceding commission paid 15.4 15.2 Total gross written premiums net of ceding commission paid $ 37.0 $ 34.9 Earned premiums $ 28.9 $ 26.0 Pricing: Gross pricing from primary market 140 bps 164 bps Gross pricing from secondary market 464 bps 434 bps Total gross pricing 177 bps 213 bps Total pricing net of ceding commission paid 125 bps 148 bps (1) For capital appreciation bonds, par is adjusted to the estimated equivalent par value for current interest paying bonds. HG Global reported pre-tax income (loss) of $(66) million in 2024 compared to $56 million in 2023. The change in pre-tax income (loss) was driven primarily by the loss on deconsolidation of BAM of $115 million in 2024. HG Global’s results included net realized and unrealized investment gains (losses) on its fixed income portfolio of $(6) million in 2024 compared to $14 million in 2023, driven by movements in interest rates. HG Global’s results included interest income on the BAM Surplus Notes of $29 million in 2024 compared to $26 million in 2023. The increase in interest income is driven by an increase in the interest rate on the BAM Surplus Notes in 2024. See Note 10 — “Municipal Bond Guarantee Insurance - BAM Surplus Notes” on page F-61. HG Global’s results also included a $5 million net deferred tax benefit related to the Bermuda economic transition adjustment in 2024 compared to $17 million in 2023. 65 During 2024, HG Global received cash payments of principal and interest on the BAM Surplus Notes totaling $30 million. Of these payments, $21 million was a repayment of principal held in the Supplemental Trust, $1 million was a payment of accrued interest held in the Supplemental Trust and $8 million was a payment of accrued interest held outside the Supplemental Trust. During 2023, HG Global received a cash payment of principal and interest on the BAM Surplus Notes of $27 million. Of this payment, $18 million was a repayment of principal held in the Supplemental Trust, $2 million was a payment of accrued interest held in the Supplemental Trust and $7 million was a payment of accrued interest held outside the Supplemental Trust. During 2024, HG Re received a distribution out of the Supplemental Trust of $80 million, which was comprised of the assignment of $59 million of accrued interest on the BAM Surplus Notes and a cash distribution of $21 million. During 2023, HG Re did not receive any distributions out of the Supplemental Trust. HG Global Balance Sheets The following tables present amounts for the HG Global segment that are presented within White Mountains’s consolidated balance sheet as of December 31, 2025 and 2024: December 31, Millions 2025 2024 Assets Fixed maturity investments, at fair value $ 693.4 $ 612.1 Short-term investments, at fair value 90.8 55.5 Total investments 784.2 667.6 Cash .1 11.5 BAM Surplus Notes, at fair value (1) 339.0 381.7 Insurance premiums receivable 11.4 4.4 Deferred acquisition costs 96.9 86.6 Other assets 5.2 27.6 Total assets $ 1,236.8 $ 1,179.4 Liabilities Preferred dividends payable to White Mountains (2) $ 527.2 $ 462.1 Preferred dividends payable to noncontrolling interests 16.3 14.2 Unearned insurance premiums 327.9 297.3 Debt 147.8 147.4 Accrued incentive compensation 1.8 1.4 Other liabilities 5.7 3.8 Total liabilities 1,026.7 926.2 Equity White Mountains’s common shareholders’ equity 228.5 266.6 Noncontrolling interests (18.4) (13.4) Total equity 210.1 253.2 Total liabilities and equity $ 1,236.8 $ 1,179.4 HG Global total equity after intercompany eliminations: White Mountains’s common shareholders’ equity $ 228.5 $ 266.6 Preferred dividends payable to White Mountains elimination (2) 527.2 462.1 HG Global total equity attributable to White Mountains’s common shareholders after intercompany eliminations $ 755.7 $ 728.7 (1) The fair value of the BAM Surplus Notes includes accrued interest receivable. (2) HG Global’s preferred dividends payable to White Mountains are eliminated in White Mountains’s consolidated financial statements. For segment reporting, these amounts are included within the HG Global segment and are eliminated against the offsetting receivables included within Other Operations. 66 Kudu Kudu provides capital solutions for boutique asset and wealth managers for a variety of purposes, including generational ownership transfers, management buyouts, acquisition and growth finance and legacy partner liquidity. Kudu also provides strategic advice to managers from time to time. Kudu deployed a total of $197 million, including transaction costs, into three new asset management firms in 2025. As of December 31, 2025, Kudu had deployed a total of $1.2 billion, including transaction costs, into 30 asset and wealth management firms globally, including three that have been exited. As of December 31, 2025, the asset and wealth management firms have combined assets under management (“AUM”) of approximately $153 billion, spanning a range of asset classes, including real estate, real assets, wealth management, hedge funds, private equity and alternative credit strategies. Since inception, Kudu’s capital was deployed at an initial average gross cash yield of 9.3% based on expected cash flows in the first year following deployment. The following table presents the components of GAAP net income (loss), EBITDA and adjusted EBITDA included in the Kudu segment for the years ended December 31, 2025, 2024 and 2023: Year Ended December 31, Millions 2025 2024 2023 Net investment income (1) $ 78.7 $ 66.7 $ 71.0 Net realized and unrealized investment gains (losses) 103.5 51.3 106.1 Other revenues 1.2 .8 — Total revenues 183.4 118.8 177.1 General and administrative expenses 17.9 15.4 19.4 Interest expense 25.9 22.1 21.2 Total expenses 43.8 37.5 40.6 GAAP pre-tax income (loss) 139.6 81.3 136.5 Income tax (expense) benefit (24.2) (16.8) (31.9) GAAP net income (loss) 115.4 64.5 104.6 Add back: Interest expense 25.9 22.1 21.2 Income tax expense (benefit) 24.2 16.8 31.9 General and administrative expenses – depreciation .2 .1 .1 Amortization of other intangible assets .3 .3 .3 EBITDA (2) 166.0 103.8 158.1 Exclude: Net realized and unrealized investment (gains) losses (103.5) (51.3) (106.1) Non-cash equity-based compensation expense .5 .3 1.0 Transaction expenses 1.9 1.7 3.5 Adjusted EBITDA (2) $ 64.9 $ 54.5 $ 56.5 (1) Net investment income includes revenues from Participation Contracts and income from short-term and other long-term investments. (2) See “NON-GAAP FINANCIAL MEASURES” on page 85. 67 The following table presents the changes to the fair value of Kudu’s Participation Contracts for the years ended December 31, 2025 and 2024: December 31, Millions 2025 2024 Beginning balance of Kudu’s Participation Contracts (1) $ 1,008.4 $ 890.5 Contributions to Participation Contracts (2) 201.7 103.5 Proceeds from Participation Contracts sold (2) (3) (28.2) (37.5) Net realized and unrealized investment gains (losses) on Participation Contracts sold and pending sale (4) 7.6 (6.3) Net unrealized investment gains (losses) on Participation Contracts - all other (5) 95.5 58.2 Ending balance of Kudu’s Participation Contracts (1) $ 1,285.0 $ 1,008.4 (1) As of December 31, 2025, 2024 and 2023, Kudu’s other long-term investments also include $6.4, $5.6 and $5.8 related to a private debt instrument. (2) Includes $6.6 of non-cash contributions to (proceeds from) Participation Contracts for the year ended December 31, 2025. (3) Includes $28.1 of proceeds receivable from Participation Contracts sold during the year ended December 31, 2024. (4) Includes net realized and unrealized investment gains (losses) recognized from Participation Contracts beginning in the quarter a contract is classified as pending sale. (5) Includes net unrealized investment gains (losses) recognized from (i) ongoing Participation Contracts and (ii) Participation Contracts prior to classification as pending sale. Kudu Results — Year Ended December 31, 2025 versus Year Ended December 31, 2024 Kudu reported total revenues of $183 million, pre-tax income of $140 million and adjusted EBITDA of $65 million in 2025 compared to total revenues of $119 million, pre-tax income of $81 million and adjusted EBITDA of $55 million in 2024. Total revenues, pre-tax income and adjusted EBITDA included $79 million of net investment income in 2025 compared to $67 million in 2024. The increase in net investment income was driven primarily by amounts earned from new deployments that Kudu made in 2024 and 2025. Total revenues and pre-tax income also included $104 million of net realized and unrealized investment gains in 2025 compared to $51 million in 2024. Net realized and unrealized investment gains in 2025 were driven by an increase in the fair value of Kudu’s Participation Contracts, primarily due to growth in assets under management at several managers and foreign currency exchange gains from a weakening U.S. dollar. Net realized and unrealized investment gains in 2024 were driven by an increase in the fair value of Kudu’s Participation Contracts, primarily due to growth in assets under management at several managers and lower discount rates across the portfolio, partially offset by foreign currency exchange losses resulting from a strengthening U.S. dollar and an unrealized loss from a publicly listed security received by Kudu in a prior sales transaction. Kudu Results—Year Ended December 31, 2024 versus Year Ended December 31, 2023 Kudu reported total revenues of $119 million, pre-tax income of $81 million and adjusted EBITDA of $55 million in 2024 compared to total revenues of $177 million, pre-tax income of $137 million and adjusted EBITDA of $57 million in 2023. Total revenues, pre-tax income and adjusted EBITDA included $67 million of net investment income in 2024 compared to $71 million in 2023. The decrease in net investment income was driven primarily by a $12 million realization of carried interest for one of Kudu’s Participation Contracts in 2023, partially offset by amounts earned from new deployments that Kudu made during 2023 and 2024. Total revenues and pre-tax income also included $51 million of net realized and unrealized investment gains in 2024 compared to $106 million in 2023. Net realized and unrealized investment gains in 2024 were driven by an increase in the fair value of Kudu’s Participation Contracts, primarily due to growth in assets under management at several managers and lower discount rates across the portfolio, partially offset by foreign currency exchange losses resulting from a strengthening U.S. dollar and an unrealized loss from a publicly listed security received by Kudu in a prior sales transaction. Net realized and unrealized investment gains in 2023 were driven by an increase in the fair value of Kudu’s Participation Contracts, primarily due to a step-up in valuation related to a pending transaction, lower discount rates across the portfolio and growth in assets under management at several managers. 68 Bamboo On January 2, 2024, White Mountains acquired a controlling interest in Bamboo. On December 5, 2025, White Mountains completed the Bamboo Sale Transaction. As a result, White Mountains deconsolidated the Bamboo Group on December 5, 2025, and Bamboo is no longer a reportable segment. Through December 5, 2025, Bamboo’s results of operations are presented within the Bamboo segment. White Mountains’s noncontrolling equity interest in the Bamboo SPV is accounted for at fair value in other long-term investments within Other Operations. See Note 2 — “Significant Transactions” on page F-19. Bamboo is a capital-light, tech- and data-enabled insurance distribution platform providing homeowners’ insurance and related products to the residential property market in California and, beginning in the third quarter of 2025, in Texas. Bamboo operates primarily through Bamboo MGA, its full-service MGA business, where the company manages all aspects of the placement process on behalf of its Capacity Providers, including product development, marketing, underwriting, policy issuance and claims oversight, and it earns commissions based on the volume and profitability of the insurance that it places. The following table presents the components of GAAP net income (loss), MGA net income (loss), MGA EBITDA and MGA adjusted EBITDA included in White Mountains’s Bamboo segment for the period from January 1, 2025 to December 5, 2025 and for the year ended December 31, 2024: Millions January 1, 2025 - December 5, 2025 Year Ended December 31, 2024 Commission and fee revenues $ 211.4 $ 134.6 Earned insurance premiums 26.7 39.4 Other revenues 8.2 5.8 Total revenues 246.3 179.8 Broker commission expenses 72.0 51.3 Loss and LAE 18.0 20.6 Acquisition expenses 9.7 14.1 General and administrative expenses 96.8 61.1 Interest expense 9.7 — Total expenses 206.2 147.1 GAAP pre-tax income (loss) 40.1 32.7 Income tax (expense) benefit (12.0) (6.9) GAAP net income (loss) 28.1 25.8 Exclude: Net (income) loss, Bamboo Captive 1.0 (1.0) MGA net income (loss) (1) 29.1 24.8 Add back: Interest expense 9.7 — Income tax expense (benefit) 12.0 6.9 Depreciation expense 1.4 .3 Amortization of other intangible assets 12.0 16.4 MGA EBITDA (1) 64.2 48.4 Exclude: Non-cash equity-based compensation expense 19.8 1.6 Software implementation expenses 4.3 1.9 Restructuring expenses 2.3 .8 Transaction expenses .8 — MGA adjusted EBITDA (1) $ 91.4 $ 52.7 (1) See “NON-GAAP FINANCIAL MEASURES” on page 85. 69 Bamboo Results—Period ended December 5, 2025 versus Year Ended December 31, 2024 Bamboo reported commission and fee revenues of $211 million and pre-tax income of $40 million for the period from January 1, 2025 to December 5, 2025, while Bamboo reported commission and fee revenues of $135 million and pre-tax income of $33 million for the year ended December 31, 2024. Bamboo reported MGA pre-tax income of $41 million and MGA adjusted EBITDA of $91 million for the period from January 1, 2025 to December 5, 2025, while Bamboo reported MGA pre-tax income of $32 million and MGA adjusted EBITDA of $53 million for the year ended December 31, 2024. Managed Premiums Managed premiums represent the total premiums placed by Bamboo during the period. Managed premiums were $705 million for the period from January 1, 2025 to December 5, 2025 and $484 million for the year ended December 31, 2024. The increase in managed premiums was driven by growth in the renewal book as well as new business volume. The following table presents Bamboo’s managed premiums for the years ended December 31, 2025, 2024 and 2023, which includes periods prior to White Mountains’s ownership of Bamboo and subsequent to the deconsolidation of Bamboo. White Mountains believes this information is useful in understanding the overall growth in Bamboo’s premium base. Year Ended December 31, Millions 2025 (1) 2024 2023 New $ 298.9 $ 301.5 $ 146.4 Net renewals, endorsements, reinstatements and cancellations 466.9 182.6 68.6 Total Managed Premiums $ 765.8 $ 484.1 $ 215.0 (1) Total managed premiums were $705.2 for the period from January 1, 2025 to December 5, 2025, including $271.7 related to new business and $433.5 related to net renewals, endorsements, reinstatements and cancellations. Distinguished On September 2, 2025, White Mountains acquired a controlling financial interest in Distinguished. White Mountains funded the Distinguished Transaction through a combination of cash on hand and new borrowings by Distinguished. White Mountains paid $225 million of cash consideration, including a post-closing purchase price adjustment of $1 million. In addition, Distinguished borrowed $50 million of incremental debt and utilized $7 million of cash on hand as part of the transaction. The consideration is subject to customary purchase price adjustments. At closing, White Mountains owned 55.5%, inclusive of its 1.7% previously-held interest, of Distinguished on a basic units outstanding basis (43.6% on a fully-diluted/ fully-converted basis, taking account of management’s equity incentives), while Distinguished management owned 4.2% of the basic units outstanding (24.7% on a fully-diluted/fully-converted basis). See Note 2 — “Significant Transactions” on page F-19. Distinguished is a full-service MGA and program administrator for specialty property and casualty insurance. Distinguished places insurance across a diversified portfolio of programs broadly grouped into two verticals. The ScaleCo vertical consists of established programs, primarily focused on real estate and hospitality end markets. The GrowthCo vertical consists of start-up programs, focused on a diversified set of specialty property and casualty insurance products across multiple industries. On behalf of its insurance carrier partners, Distinguished typically manages all aspects of the placement process, including product development, marketing, underwriting and policy issuance. Distinguished earns commissions based on the volume and profitability of the insurance that it places. Distinguished does not retain insurance risk. 70 The following table presents the components of GAAP net income (loss), ScaleCo net income (loss), ScaleCo EBITDA and ScaleCo adjusted EBITDA included in White Mountains’s Distinguished segment for the period from September 2, 2025, the date of acquisition, through December 31, 2025: Millions September 2, 2025 - December 31, 2025 Commission and fee revenues $ 56.7 Other revenues 1.0 Total revenues 57.7 Broker commission expenses 22.1 General and administrative expenses 47.0 Interest expense 5.1 Total expenses 74.2 GAAP pre-tax income (loss) (16.5) Income tax (expense) benefit 2.6 GAAP net income (loss) (13.9) Exclude: Net (income) loss, GrowthCo 9.8 ScaleCo net income (loss) (1) (4.1) Add back: Interest expense 5.1 Income tax expense (benefit) (2.6) Depreciation expense .2 Amortization of other intangible assets 7.8 ScaleCo EBITDA (1) 6.4 Exclude: Non-cash equity-based compensation expense 2.2 Transaction expenses .5 ScaleCo adjusted EBITDA (1) $ 9.1 (1) See “NON-GAAP FINANCIAL MEASURES” on page 85. Distinguished Results – Period from September 2, 2025 through December 31, 2025 Distinguished reported commission and fee revenues of $57 million, pre-tax loss of $17 million and ScaleCo adjusted EBITDA of $9 million for the period from September 2, 2025 through December 31, 2025. Managed Premiums and Commission and Fee Revenues Managed premiums, which represent the total premiums placed by Distinguished, were $188 million for the period from September 2, 2025 through December 31, 2025. The following table presents Distinguished’s managed premiums and commission and fee revenues by vertical for the period from September 2, 2025 through December 31, 2025. September 2, 2025 - December 31, 2025 Millions Managed Premiums Commission and Fee Revenues ScaleCo $ 141.1 $ 41.3 GrowthCo 46.8 15.4 Total $ 187.9 $ 56.7 For the year ended December 31, 2025, Distinguished’s total managed premiums were $568 million, which increased 6% compared to the year ended December 31, 2024. This includes periods prior to White Mountains’s ownership of Distinguished, which White Mountains believes is useful in understanding the overall size and growth in Distinguished’s premium base. 71 Other Operations On December 5, 2025, White Mountains closed the Bamboo Sale Transaction. White Mountains received net cash proceeds at closing of $848 million and retained an indirect equity interest valued at $250 million. White Mountains’s indirect equity interest is held through the Bamboo SPV. White Mountains’s Other Operations recognized a net gain of $816 million, which was comprised of an $849 million net gain on sale of the Bamboo Group, partially offset by $33 million of parent company compensation costs recorded within general and administrative expenses. See Note 2 — “Significant Transactions” on page F-19. The following table presents the components of pre-tax income (loss) included in White Mountains’s Other Operations for the years ended December 31, 2025, 2024 and 2023: Year Ended December 31, Millions 2025 2024 2023 Earned insurance premiums $ 22.2 $ 32.7 $ — Net investment income 32.1 35.6 30.1 Net realized and unrealized investment gains (losses) 80.0 57.0 188.5 Net realized and unrealized investment gains (losses) from investment in MediaAlpha 29.6 38.0 27.1 Commission and fee revenues 16.4 14.8 13.2 Net gain on sale of the Bamboo Group 849.3 — — Other revenues 200.6 56.8 80.5 Total revenues 1,230.2 234.9 339.4 Loss and LAE 20.0 12.1 — Acquisition expenses 8.3 12.1 — Cost of sales 151.8 29.6 40.4 General and administrative expenses 236.7 169.5 182.3 Interest expense 3.2 2.5 3.7 Total expenses 420.0 225.8 226.4 Pre-tax income (loss) $ 810.2 $ 9.1 $ 113.0 Other Operations Results—Year Ended December 31, 2025 versus Year Ended December 31, 2024 White Mountains’s Other Operations reported pre-tax income of $810 million in 2025 compared to $9 million in 2024. Results in 2025 were driven primarily by the Bamboo Sale Transaction, which resulted in a net gain of $816 million, including the impact of parent company compensation costs recorded within general and administrative expenses. White Mountains’s Other Operations reported unrealized investment gains from its investment in MediaAlpha of $30 million in 2025 compared to net realized and unrealized investment gains of $38 million in 2024. Excluding MediaAlpha, White Mountains’s Other Operations reported net realized and unrealized investment gains of $80 million in 2025 compared to $57 million in 2024. The increase in net realized and unrealized investment gains was driven primarily by higher gains from other long-term investments in 2025 compared to 2024. White Mountains’s Other Operations reported net investment income of $32 million in 2025 compared to $36 million in 2024. See “Summary of Investment Results” on page 74. White Mountains’s Other Operations reported $201 million of other revenues in 2025 compared to $57 million in 2024. White Mountains’s Other Operations reported $152 million of cost of sales in 2025 compared to $30 million in 2024. The increases in other revenues and cost of sales were driven primarily by the acquisition of Enterprise Solutions by WTM Partners in 2025. 72 White Mountains’s Other Operations reported general and administrative expenses of $237 million in 2025 compared to $170 million in 2024. The increase in general and administrative expenses was driven primarily by higher incentive compensation costs, largely in connection with the Bamboo Sale Transaction, higher transaction costs and the consolidation of Enterprise Solutions. General and administrative expenses included $120 million of parent company compensation and benefits in 2025 compared to $92 million in 2024. The Bamboo CRVs reported $5 million of pre-tax loss in 2025 compared to $9 million of pre-tax income in 2024. The Bamboo CRVs’ results included earned premiums of $22 million, loss and LAE of $20 million and acquisition expenses of $8 million in 2025 compared to earned premiums of $33 million, loss and LAE of $12 million and acquisition expenses of $12 million in 2024. Loss and LAE in 2025 included approximately $12 million related to the January 2025 California wildfires. Share Repurchases In the year ended December 31, 2025, White Mountains repurchased and retired 100,581 of its common shares for $203 million at an average share price of $2,013.67, or 92% of White Mountains’s book value per share as of December 31, 2025. This included 64,064 shares repurchased through the self-tender offer in December. Other Operations Results—Year Ended December 31, 2024 versus Year Ended December 31, 2023 White Mountains’s Other Operations reported pre-tax income of $9 million in 2024 compared to $113 million in 2023. White Mountains’s Other Operations reported net realized and unrealized investment gains from its investment in MediaAlpha of $38 million in 2024 compared to unrealized investment gains of $27 million in 2023. Excluding MediaAlpha, White Mountains’s Other Operations reported net realized and unrealized investment gains of $57 million in 2024 compared to $189 million in 2023. The decrease in net realized and unrealized investment gains was driven primarily by lower unrealized gains from other long-term investments in 2024 compared to 2023. White Mountains’s Other Operations reported net investment income of $36 million in 2024 compared to $30 million in 2023. See “Summary of Investment Results” on page 74. White Mountains’s Other Operations reported $57 million of other revenues in 2024 compared to $81 million in 2023. White Mountains’s Other Operations reported $30 million of cost of sales in 2024 compared to $40 million in 2023. The decreases in other revenues and cost of sales were driven primarily by a business sold within Other Operations in 2023. White Mountains’s Other Operations reported general and administrative expenses of $170 million in 2024 compared to $182 million in 2023. General and administrative expenses included $92 million of parent company compensation and benefits in 2024 compared to $94 million in 2023. White Mountains’s Other Operations reported $9 million of pre-tax income in 2024 related to the Bamboo CRV that incepted on April 1, 2024. The Bamboo CRV’s results included earned premiums of $33 million, loss and LAE of $12 million and acquisition expenses of $12 million. Share Repurchases In the year ended December 31, 2024, White Mountains repurchased and retired 5,269 of its common shares for $8 million at an average share price of $1,505.01. 73 II. Summary of Investment Results White Mountains’s total investment results include results from all segments. For purposes of discussing rates of return, percentages are presented gross of management fees and trading expenses. Effective December 5, 2025, White Mountains no longer consolidates Bamboo. Through December 5, 2025, White Mountains’s consolidated financial statements included Bamboo’s investment results. Effective July 1, 2024, White Mountains no longer consolidates BAM. Through June 30, 2024, White Mountains’s consolidated financial statements included BAM’s investment results. See Note 2 — “Significant Transactions” on page F-19. Gross Investment Returns and Benchmark Returns The following table presents the pre-tax time-weighted investment returns for White Mountains’s consolidated portfolio for the years ended December 31, 2025, 2024 and 2023: Year Ended December 31, 2025 2024 2023 Fixed income investments 5.9 % 4.3 % 5.8 % Bloomberg U.S. Intermediate Aggregate Index 7.5 % 2.5 % 5.2 % Common equity securities 10.6 % 11.3 % 13.4 % Investment in MediaAlpha 14.7 % (0.9) % 11.8 % Other long-term investments 13.2 % 8.9 % 20.6 % Total common equity securities, investment in MediaAlpha and other long-term investments 13.1 % 10.0 % 18.5 % Total common equity securities and other long-term investments 13.0 % 9.4 % 19.0 % S&P 500 Index (total return) 17.9 % 25.0 % 26.3 % Total consolidated portfolio 9.1 % 6.9 % 11.4 % Total consolidated portfolio - excluding MediaAlpha (1) 8.9 % 6.5 % 11.4 % (1) See “NON-GAAP FINANCIAL MEASURES” on page 85. Investment Returns—Year Ended December 31, 2025 versus Year Ended December 31, 2024 White Mountains’s total consolidated portfolio return on invested assets was 9.1% in 2025, which included $30 million of unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, the total consolidated portfolio return on invested assets was 8.9% in 2025. Excluding MediaAlpha, investment returns in 2025 were driven primarily by net investment income and net unrealized investment gains from other long-term investments, net investment income from the fixed income portfolio and net realized gains from common equity securities. White Mountains’s total consolidated portfolio return on invested assets was 6.9% in 2024, which included $38 million of net realized and unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, the total consolidated portfolio return on invested assets was 6.5% in 2024. Excluding MediaAlpha, investment returns in 2024 were driven primarily by net investment income and net realized and unrealized investment gains from other long-term investments, net investment income from the fixed income portfolio and net unrealized gains from common equity securities. Fixed Income Results White Mountains’s fixed income portfolio, including short-term investments, totaled $4.7 billion and $3.5 billion as of December 31, 2025 and 2024, which represented 56% and 54% of total invested assets. The duration of White Mountains’s fixed income portfolio, including short-term investments, was 1.5 years and 1.9 years as of December 31, 2025 and 2024. The change in the fair value and duration was driven primarily by cash inflows into the fixed income portfolio, principally related to the proceeds from the Bamboo Sale Transaction. White Mountains’s fixed income portfolio includes fixed maturity and short-term investments held on deposit or as collateral. See Note 3 — “Investment Securities” on page F-23. White Mountains’s fixed income portfolio returned 5.9% in 2025 compared to 4.3% in 2024, underperforming and outperforming the Bloomberg U.S. Intermediate Aggregate Index returns of 7.5% and 2.5% for the comparable periods. Results in 2025 were driven primarily by net investment income and White Mountains’s short duration positioning as interest rates declined in the period. Results in 2024 were driven primarily by net investment income. 74 Common Equity Securities, Investment in MediaAlpha and Other Long-Term Investments Results White Mountains’s portfolio of common equity securities, its investment in MediaAlpha and other long-term investments totaled $3.7 billion and $3.0 billion as of December 31, 2025 and 2024, which represented 44% and 46% of total invested assets. The change was driven primarily by increased exposure to other long-term investments, principally due to investments in new unconsolidated equities and an increase in the fair value of Kudu’s Participation Contracts. See Note 3 — “Investment Securities” on page F-23. White Mountains’s portfolio of common equity securities, its investment in MediaAlpha and other long-term investments returned 13.1% in 2025, which included $30 million of unrealized investment gains from White Mountains’s investment in MediaAlpha. White Mountains’s portfolio of common equity securities and other long-term investments returned 13.0% in 2025. White Mountains’s portfolio of common equity securities, its investment in MediaAlpha and other long-term investments returned 10.0% in 2024, which included $38 million of net realized and unrealized investment gains from White Mountains’s investment in MediaAlpha. White Mountains’s portfolio of common equity securities and other long-term investments returned 9.4% in 2024. White Mountains’s portfolio of common equity securities generally consists of international listed equity funds, primarily held at Ark, and passive ETFs. White Mountains’s ETFs seek to provide investment results generally corresponding to the performance of the S&P 500 Index. White Mountains’s portfolio of common equity securities was $483 million and $650 million as of December 31, 2025 and 2024. The decrease in common equity securities in 2025 was due to the sale of White Mountains’s ETF portfolio in the first half of 2025 to fund planned capital deployments. See Note 2 — “Significant Transactions” on page F-19. Subsequent to the Bamboo Sale Transaction, White Mountains began to reestablish its ETF portfolio. White Mountains’s portfolio of common equity securities returned 10.6% in 2025 compared to 11.3% in 2024, underperforming the S&P 500 Index returns of 17.9% and 25.0% for the comparable periods. The underperformance in each period was driven primarily by certain international listed equity funds that employ a market neutral strategy. In 2025, the underperformance was also attributable to the sale of White Mountains’s ETF portfolio in the first half of the year. White Mountains maintains a portfolio of other long-term investments that consists primarily of unconsolidated entities, including Kudu’s Participation Contracts, the Bamboo SPV, PassportCard/DavidShield and the BroadStreet SPV, as well as private equity funds and hedge funds, a bank loan fund and Lloyd’s trust deposits. White Mountains’s portfolio of other long-term investments totaled $3.0 billion and $2.2 billion as of December 31, 2025 and 2024. White Mountains’s portfolio of other long-term investments returned 13.2% in 2025 compared to 8.9% in 2024. Returns for 2025 were driven primarily by net investment income and net realized and unrealized investment gains from Kudu’s Participation Contracts, as well as net investment income and net realized and unrealized investment gains from certain unconsolidated entities, private equity funds and hedge funds. Returns for 2024 were driven primarily by net investment income and net realized and unrealized investment gains from Kudu’s Participation Contracts, as well as net unrealized investment gains from a bank loan fund and ILS funds. Investment Returns—Year Ended December 31, 2024 versus Year Ended December 31, 2023 White Mountains’s total consolidated portfolio return on invested assets was 6.9% in 2024, which included $38 million of net realized and unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, the total consolidated portfolio return on invested assets was 6.5% in 2024. Excluding MediaAlpha, investment returns in 2024 were driven primarily by net investment income and net unrealized investment gains from other long-term investments, net investment income from the fixed income portfolio and net unrealized gains from common equity securities. White Mountains’s total consolidated portfolio return on invested assets, both including and excluding White Mountains’s investment in MediaAlpha, was 11.4% in 2023. The total consolidated portfolio return included $27 million of unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, investment returns in 2023 were driven primarily by net investment income and net realized and unrealized investment gains from the other long-term investments and fixed income portfolios. Fixed Income Results White Mountains’s fixed income portfolio, including short-term investments, totaled $3.5 billion and $3.6 billion as of December 31, 2024 and 2023, which represented 54% and 56% of total invested assets. The duration of White Mountains’s fixed income portfolio, including short-term investments, was 1.9 years as of both December 31, 2024 and 2023. White Mountains’s fixed income portfolio includes fixed maturity and short-term investments held on deposit or as collateral. See Note 3 — “Investment Securities” on page F-23. White Mountains’s fixed income portfolio returned 4.3% in 2024 compared to 5.8% in 2023, outperforming the Bloomberg U.S. Intermediate Aggregate Index returns of 2.5% and 5.2% for the comparable periods. Results in 2024 were driven primarily by net investment income. Results in 2023 were driven primarily by net investment income and net unrealized investment gains as shorter-term interest rates declined marginally in the period. 75 Common Equity Securities, Investment in MediaAlpha and Other Long-Term Investments Results White Mountains’s portfolio of common equity securities, its investment in MediaAlpha and other long-term investments totaled $3.0 billion and $2.8 billion as of December 31, 2024 and 2023, which represented 46% and 44% of total invested assets. See Note 3 — “Investment Securities” on page F-23. White Mountains’s portfolio of common equity securities, its investment in MediaAlpha and other long-term investments returned 10.0% in 2024, which included $38 million of net realized and unrealized investment gains from White Mountains’s investment in MediaAlpha. White Mountains’s portfolio of common equity securities and other long-term investments returned 9.4% in 2024. White Mountains’s portfolio of common equity securities, its investment in MediaAlpha and other long-term investments returned 18.5% in 2023, which included $27 million of unrealized investment gains from White Mountains’s investment in MediaAlpha. White Mountains’s portfolio of common equity securities and other long-term investments returned 19.0% in 2023. White Mountains’s portfolio of common equity securities was $650 million and $538 million as of December 31, 2024 and 2023. White Mountains’s portfolio of common equity securities returned 11.3% in 2024 compared to 13.4% in 2023, underperforming the S&P 500 Index returns of 25.0% and 26.3% for the comparable periods. The underperformance in 2024 and 2023 was driven primarily by certain international listed equity funds that employ a market neutral strategy. White Mountains’s portfolio of other long-term investments totaled $2.2 billion and $2.0 billion as of December 31, 2024 and 2023. White Mountains’s portfolio of other long-term investments returned 8.9% in 2024 compared to 20.6% in 2023. Returns for 2024 were driven primarily by net investment income and net realized and unrealized investment gains from Kudu’s Participation Contracts, as well as net unrealized investment gains from a bank loan fund and ILS funds. Returns for 2023 were driven primarily by net investment income and net realized and unrealized investment gains from Kudu’s Participation Contracts, net realized and unrealized investment gains from private equity funds, hedge funds and unconsolidated entities, as well as net investment income and unrealized gains from ILS funds. Portfolio Composition The following table presents the composition of White Mountains’s total investment portfolio as of December 31, 2025 and 2024: December 31, 2025 December 31, 2024 $ in Millions Carrying Value % of Total Carrying Value % of Total Fixed maturity investments $ 2,770.5 33.3 % $ 2,511.6 38.8 % Short-term investments 1,881.7 22.6 964.2 14.9 Common equity securities 483.0 5.8 650.0 10.0 Investment in MediaAlpha 231.2 2.8 201.6 3.1 Other long-term investments 2,958.5 35.5 2,150.2 33.2 Total investments $ 8,324.9 100.0 % $ 6,477.6 100.0 % The following table presents the breakdown of White Mountains’s fixed maturity investments as of December 31, 2025 and 2024 by credit class, based upon issuer credit ratings provided by Standard & Poor’s, or if unrated by Standard & Poor’s, long-term obligation ratings provided by Moody’s: December 31, 2025 $ in Millions Amortized Cost % of Total Carrying Value % of Total U.S. government and government-sponsored entities (1) $ 826.0 29.8 % $ 814.2 29.4 % AAA/Aaa 270.2 9.7 271.9 9.8 AA/Aa 242.8 8.8 244.4 8.8 A/A 713.1 25.7 711.7 25.7 BBB/Baa 710.9 25.6 716.9 25.9 BB/Ba 3.2 0.1 3.2 0.1 Other/not rated 8.6 0.3 8.2 0.3 Total fixed maturity investments $ 2,774.8 100.0 % $ 2,770.5 100.0 % (1)Includes 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). 76 December 31, 2024 $ in Millions Amortized Cost % of Total Carrying Value % of Total U.S. government and government-sponsored entities (1) $ 857.7 33.4 % $ 831.7 33.1 % AAA/Aaa 154.7 6.0 154.3 6.1 AA/Aa 221.4 8.6 215.9 8.6 A/A 627.7 24.5 608.5 24.2 BBB/Baa 693.7 27.0 688.7 27.5 BB/Ba 5.5 0.2 5.4 0.2 Other/not rated 8.5 0.3 7.1 0.3 Total fixed maturity investments $ 2,569.2 100.0 % $ 2,511.6 100.0 % (1)Includes 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). 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, 2025 and 2024. 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, 2025 December 31, 2024 Millions Cost or Amortized Cost Carrying Value Cost or Amortized Cost Carrying Value Due in one year or less $ 455.3 $ 455.2 $ 205.8 $ 203.9 Due after one year through five years 1,349.8 1,354.1 1,494.5 1,478.7 Due after five years through ten years 199.0 199.3 206.1 193.2 Due after ten years 21.7 21.9 25.3 25.2 Mortgage and asset-backed securities and collateralized loan obligations 749.0 740.0 637.5 610.6 Total fixed maturity investments $ 2,774.8 $ 2,770.5 $ 2,569.2 $ 2,511.6 77 The following table presents the composition of White Mountains’s other long-term investments portfolio as of December 31, 2025 and 2024: December 31, 2025 December 31, 2024 $ in Millions Carrying Value % of Total Carrying Value % of Total Kudu’s Participation Contracts $ 1,285.0 43.4 % $ 1,008.4 46.9 % Bamboo SPV 250.0 8.5 — — PassportCard/DavidShield 170.0 5.7 150.0 7.0 BroadStreet SPV 160.0 5.4 — — Elementum 35.0 1.2 35.0 1.6 Other unconsolidated entities 73.7 2.5 63.6 3.0 Total unconsolidated entities 1,973.7 1,257.0 Private equity funds and hedge funds 395.2 13.4 360.6 16.8 Bank loan fund 308.5 10.4 264.7 12.3 Lloyd’s trust deposits 180.4 6.1 149.9 7.0 ILS funds 50.1 1.7 74.0 3.4 Private debt instruments 16.9 0.6 14.9 0.7 Other 33.7 1.1 29.1 1.3 Total other long-term investments $ 2,958.5 100.0 % $ 2,150.2 100.0 % Foreign Currency Exposure As of December 31, 2025, White Mountains had foreign currency exposure on $376 million of net assets, primarily related to Ark/WM Outrigger’s non-U.S. contracts, Kudu’s non-U.S. Participation Contracts and a private debt instrument, as well as certain other foreign consolidated and unconsolidated entities. The following table presents the fair value of White Mountains’s foreign denominated net assets (liabilities) by segment as of December 31, 2025: $ in Millions Currency Ark/ WM Outrigger Kudu Other Operations Total Fair Value % of Total Shareholders’ Equity CAD $ 109.4 $ 55.0 $ — $ 164.4 2.7 % AUD 54.4 76.5 — 130.9 2.1 EUR (13.8) 64.9 — 51.1 0.8 GBP 28.6 — — 28.6 0.5 All other — — 1.4 1.4 — Total $ 178.6 $ 196.4 $ 1.4 $ 376.4 6.1 % 78 III. Income Taxes As of December 31, 2025, the primary jurisdictions in which the Company’s subsidiaries and branches operated and were subject to tax are Israel, Luxembourg, the United Kingdom and the United States. On December 15, 2022, European Union Member States voted to adopt the EU Minimum Tax Directive in conformity with the OECD Pillar Two initiative. The Pillar Two initiative includes a set of model rules that are generally designed to impose a top-up tax on a large multinational enterprise group to the extent that the group is not subject to an effective tax rate of at least 15% in each jurisdiction in which the group has a consolidated affiliate or permanent establishment. The EU Minimum Tax Directive required European Union Member States to enact conforming law by December 31, 2023. The main rule of the EU Minimum Tax Directive, the IIR, was to become effective for fiscal years beginning on or after December 31, 2023, while the UTPR was to become effective for fiscal years beginning on or after December 31, 2024. The EU Minimum Tax Directive also permits European Union Member States to elect to apply a QDMTT for fiscal years beginning on or after December 31, 2023. On July 11, 2023, the United Kingdom enacted conforming Pillar Two legislation including the IIR and QDMTT, which became effective for fiscal years beginning on or after December 31, 2023. On March 20, 2025, the United Kingdom enacted legislation adopting the Pillar Two UTPR effective for fiscal years beginning on or after December 31, 2024. Under the legislation, the effective date of the UTPR is deferred until fiscal years beginning on or after December 31, 2029 for U.K. companies in consolidated groups that meet certain requirements. To qualify for the deferral, generally the group must (i) have consolidated affiliates and permanent establishments in six or fewer countries and (ii) have no more than €50 million of net tangible assets outside of the country where the group has the largest amount of net tangible assets. White Mountains expects to meet the requirements to be exempt from the U.K. UTPR until January 1, 2030. On December 20, 2023, Luxembourg enacted conforming Pillar Two legislation including the IIR and QDMTT, which became effective for fiscal years beginning on or after December 31, 2023, and the UTPR, which became effective for fiscal years beginning on or after December 31, 2024. The Luxembourg Pillar Two legislation defers the effective date of the QDMTT and UTPR until fiscal years beginning on or after December 31, 2028 and 2029, respectively, for Luxembourg companies in consolidated groups that meet certain requirements. To qualify for the deferral, generally the group must (i) have consolidated affiliates and permanent establishments in six or fewer countries and (ii) have no more than €50 million of net tangible assets outside of the country where the group has the largest amount of net tangible assets. White Mountains expects to meet the requirements to be exempt from the Luxembourg QDMTT and UTPR until January 1, 2029 and 2030, respectively. On December 27, 2023, Bermuda enacted a 15% corporate income tax that became effective on January 1, 2025. The Bermuda legislation defers the effective date for five years for Bermuda companies in consolidated groups that meet certain requirements. To qualify for the deferral, generally the group must (i) have consolidated affiliates and permanent establishments in six or fewer countries, (ii) have no more than €50 million of net tangible assets outside of the country where the group has the largest amount of net tangible assets and (iii) not have a consolidated Bermuda affiliate or Bermuda permanent establishment directly or indirectly owned by a parent entity that is subject to the Pillar Two IIR in any jurisdiction. White Mountains expects to meet the requirements to be exempt from the Bermuda corporate income tax until January 1, 2030. The Bermuda legislation also provides for an optional economic transition adjustment that can decrease or increase future years’ taxable income. Under GAAP, this economic transition adjustment was required to be recorded as a deferred tax asset or liability as of December 31, 2023 if a company intended to apply the adjustment to compute its taxable income. Accordingly, White Mountains recognized a net deferred tax benefit of $68 million in 2023, of which $51 million was recognized at Ark and $17 million was recognized at HG Global. As of July 1, 2024, White Mountains no longer consolidates BAM. As a result of the deconsolidation, the BAM Surplus Notes are recorded at fair value, which resulted in the reversal of a $5 million deferred tax liability related to the economic transition adjustment, generating a $5 million deferred tax benefit in 2024. On December 11, 2025, Bermuda enacted legislation that changed the scope of assets and liabilities subject to the economic transition adjustment. This legislation resulted in the reversal of a $5 million deferred tax liability related to the economic transition adjustment, generating a $5 million deferred tax benefit in 2025. On January 15, 2025, the OECD released administrative guidance on its Pillar Two model rules. The January 2025 OECD Administrative Guidance provides that, subject to limited exceptions, deferred tax expense attributable to deferred tax assets resulting from the introduction of a new corporate income tax after November 30, 2021 is to be excluded when assessing whether a multinational enterprise group has an effective tax rate of at least 15% in the jurisdiction that adopted the corporate income tax. Deferred tax assets associated with the economic transition adjustment recorded under the Bermuda corporate income tax are expected to be within the scope of the January 2025 OECD Administrative Guidance. On December 17, 2025, Luxembourg enacted legislation that adopts the January 2025 OECD Administrative Guidance. Accordingly, in any future year in which the economic transition adjustment deferred tax asset is utilized, White Mountains expects to incur a top-up tax under the Luxembourg UTPR equal to the amount of the deferred tax expense for that year associated with the economic transition adjustment. Consequently, White Mountains expects to derive no economic benefit from the Bermuda economic transition adjustment and intends to opt out of the economic transition adjustment upon becoming subject to Bermuda corporate income tax. Accordingly, White Mountains recognized a deferred tax expense of $78 million in 2025 to reverse the net deferred tax asset related to the Bermuda economic transition adjustment. 79 On December 11, 2025, the Bermuda government enacted legislation providing certain incentives for Bermuda-based employment, training, local expenditure and community development. The incentives are based on qualifying expenditures of eligible Bermuda entities and are provided in the form of a refundable tax credit. A Bermuda entity may be eligible for the incentives regardless of whether it is subject to the Bermuda corporate income tax. For the year ended December 31, 2025, White Mountains accrued a $10 million benefit for the incentives as a reduction to general and administrative expenses. On July 4, 2025, the U.S. enacted the OBBBA. White Mountains does not expect the OBBBA to have a material impact on its financial statements. White Mountains reported income tax expense of $127 million in 2025 on pre-tax income of $1,329 million. The difference between White Mountains’s effective tax rate and the current U.S. statutory rate of 21% was driven primarily by income generated in jurisdictions with lower tax rates than the United States, income attributable to certain gains not subject to tax in Luxembourg, a full valuation allowance on net deferred tax assets in certain U.S. operations (consisting of Other Operations), withholding taxes and state income taxes. The effective rate also differed from the U.S. statutory rate of 21% due to the $73 million net deferred tax expense related to the reversal of the Bermuda economic transition adjustment. White Mountains reported income tax expense of $33 million in 2024 on pre-tax income of $317 million. The difference between White Mountains’s effective tax rate and the current U.S. statutory rate of 21% was driven primarily by income generated in jurisdictions with lower tax rates than the United States, a full valuation allowance on net deferred tax assets in certain U.S. operations (consisting of Other Operations and BAM), withholding taxes and state income taxes. White Mountains reported income tax benefit of $16 million in 2023 on pre-tax income of $565 million. The difference between White Mountains’s effective tax rate and the current U.S. statutory rate of 21% was driven primarily by income generated in jurisdictions with lower tax rates than the United States, a full valuation allowance on net deferred tax assets in certain U.S. operations (consisting of Other Operations and BAM), withholding taxes and state income taxes. The effective rate also differed from the U.S. statutory rate of 21% due to the $68 million deferred tax benefit related to the Bermuda economic transition adjustment. LIQUIDITY AND CAPITAL RESOURCES Operating Cash and Short-term Investments Holding Company Level The primary sources of cash for the Company and certain of its intermediate holding companies are expected to be distributions from its insurance, reinsurance and other operating subsidiaries, net investment income, proceeds from sales, repayments and maturities of investments, borrowings from credit facilities, capital raising activities and, from time to time, proceeds from sales of operating subsidiaries. The primary uses of cash are expected to be general and administrative expenses, purchases of investments, payments to tax authorities, payments on and repurchases/retirements of debt obligations, dividend payments to holders of the Company’s common shares, distributions to noncontrolling interest holders of consolidated subsidiaries, contributions to operating subsidiaries and, from time to time, purchases of operating subsidiaries and repurchases of the Company’s common shares. Operating Subsidiary Level The primary sources of cash for White Mountains’s insurance, reinsurance and other operating subsidiaries are expected to be premium and fee collections, commissions, net investment income, proceeds from sales, repayments and maturities of investments, contributions from holding companies, borrowings from credit facilities and capital raising activities. The primary uses of cash are expected to be claim payments, policy acquisition costs, general and administrative expenses, broker commission expenses, cost of sales, purchases of investments, payments to tax authorities, payments on and repurchases/retirements of debt obligations, distributions to holding companies, distributions to noncontrolling interest holders and, from time to time, purchases of operating subsidiaries. Both internal and external forces influence White Mountains’s financial condition, results of operations and cash flows. Premium and fee collections, investment returns, claim payments and cost of sales may be impacted by changing rates of inflation and other economic conditions. Some time may lapse between the occurrence of an insured loss, the reporting of the loss to White Mountains’s insurance and reinsurance operating subsidiaries and the settlement of the liability for that loss. The exact timing of the payment of losses cannot be predicted with certainty. White Mountains’s insurance and reinsurance operating subsidiaries maintain portfolios of invested assets with varying maturities and a substantial amount of cash and short-term investments to provide adequate liquidity for the payment of claims. Management believes that White Mountains’s cash balances, cash flows from operations and routine sales and maturities of investments are adequate to meet expected cash requirements for the foreseeable future at both a holding company and insurance, reinsurance and other operating subsidiary level. 80 Dividend Capacity Following is a description of the dividend capacity of White Mountains’s insurance and reinsurance and other operating subsidiaries: Ark/WM Outrigger During any 12-month period, GAIL, a class 4 licensed Bermuda insurer, has the ability to (i) make capital distributions of up to 15% of its total statutory capital per the previous year’s statutory financial statements or (ii) make dividend payments of up to 25% of its total statutory capital and surplus per the previous year’s statutory financial statements, without prior approval of Bermuda regulatory authorities. Accordingly, GAIL will have the ability to pay a dividend of up to $425 million during 2026, which is equal to 25% of its statutory capital and surplus of $1,700 million as of December 31, 2025, subject to meeting all appropriate liquidity and solvency requirements and the filing of its December 31, 2025 statutory financial statements. During 2025, GAIL did not pay any dividends to its immediate parent. During 2025, Ark paid a $41 million dividend to shareholders, including $30 million that was paid to White Mountains. As of December 31, 2025, Ark and its intermediate holding companies had $9 million of net unrestricted cash and short-term investments outside of its regulated and unregulated insurance and reinsurance operating subsidiaries. WM Outrigger Re is a special purpose insurer subject to regulation and supervision by the BMA. WM Outrigger Re does not require regulatory approval to pay dividends; however, its dividend capacity is limited to amounts held outside of the collateral trust pursuant to its reinsurance agreement with GAIL. As of December 31, 2025, WM Outrigger Re had less than $1 million of net unrestricted cash held outside the collateral trust. As of December 31, 2025, WM Outrigger Re had $232 million of statutory capital and surplus and $246 million of assets held in the collateral trusts pursuant to the reinsurance agreement with GAIL. During 2025, White Mountains received a distribution of $10 million from WM Outrigger Re. HG Global As of December 31, 2025, HG Global had $619 million face value of preferred shares outstanding, of which White Mountains owned 96.9%. Holders of the HG Global preferred shares are entitled to receive cumulative dividends at a fixed annual rate of 6.0% on a quarterly basis, payable when and if declared by HG Global. As of December 31, 2025, HG Global has accrued $544 million of dividends payable to holders of its preferred shares, $527 million of which is payable to White Mountains and is eliminated in consolidation. As of December 31, 2025, HG Global and its subsidiaries had $32 million of net unrestricted cash and short-term investments outside of HG Re. HG Re is a special purpose insurer subject to regulation and supervision by the BMA. HG Re does not require regulatory approval to pay dividends; however, its dividend capacity is limited to amounts held outside of the Collateral Trusts. As of December 31, 2025, HG Re had $4 million of net unrestricted cash and short-term investments. As of December 31, 2025, HG Re had $179 million of accrued interest on the BAM Surplus Notes held outside the Collateral Trusts. As of December 31, 2025, HG Re had $732 million of statutory capital and surplus and $1,007 million of assets held in the Collateral Trusts. HG Global has two primary sources of cash flows: (i) interest payments on the BAM Surplus Notes that are made outside the Collateral Trusts and (ii) releases of excess balances from the Collateral Trusts. During 2025, HG Global received cash payments of principal and interest on the BAM Surplus Notes totaling $35 million. Of these payments, $24 million was a repayment of principal held in the Supplemental Trust, less than $1 million was a payment of accrued interest held in the Supplemental Trust and $11 million was a payment of accrued interest held outside the Supplemental Trust. During 2025, HG Re received a distribution from the Supplemental Trust of $61 million, which consisted of an assignment of accrued interest on the BAM Surplus Notes of $30 million and a cash distribution of $31 million. See Note 10 — “Municipal Bond Guarantee Reinsurance” on page F-60. Kudu During 2025, Kudu distributed $15 million to unitholders, substantially all of which was paid to White Mountains. As of December 31, 2025, Kudu had $49 million of net unrestricted cash and short-term investments. Bamboo During the period from January 1, 2025 through December 5, 2025, Bamboo distributed $121 million to shareholders, $87 million of which was paid to White Mountains. Distinguished For the period from September 2, 2025, the date of acquisition, through December 31, 2025, Distinguished did not make any distributions to unitholders. As of December 31, 2025, Distinguished had $40 million of net unrestricted cash and short-term investments. 81 Other Operations During 2025, White Mountains paid a $3 million common share dividend. As of December 31, 2025, the Company and its intermediate holding companies had $975 million of net unrestricted cash, short-term investments and fixed maturity investments, $231 million of MediaAlpha common stock, $31 million of common equity securities and $294 million of private equity and hedge funds, ILS funds and certain unconsolidated entities. During 2025, White Mountains received a distribution of $17 million from the Bamboo CRVs. Financing The following table presents White Mountains’s capital structure as of December 31, 2025 and 2024: December 31, $ in Millions 2025 2024 Ark 2021 Subordinated Notes (1) (2) $ 159.7 $ 154.5 HG Global Senior Notes (1) (2) 147.8 147.4 Kudu Credit Facility (1) (2) 350.4 238.6 Distinguished Credit Facility (1) (2) 129.9 — Distinguished Other Debt (1) (2) 10.9 — Other Operations debt (1) (2) 38.3 22.0 Total debt 837.0 562.5 Redeemable noncontrolling interests 131.5 — Nonredeemable noncontrolling interests 698.2 647.3 Total White Mountains’s common shareholders’ equity 5,425.4 4,483.7 Total capital $ 7,092.1 $ 5,693.5 Total debt to total capital 11.8 % 9.9 % (1)See Note 7 — “Debt” on page F-49 for details of debt arrangements. (2) Net of unamortized issuance costs and original issue discount. On July 16, 2025, the Company entered into a credit agreement, which established a senior unsecured revolving credit facility of up to $250 million that matures on July 16, 2028 (the “WTM Credit Facility”). As of December 31, 2025, the WTM Credit Facility is undrawn. Management believes that White Mountains has the flexibility and capacity to obtain funds externally through debt or equity financing on both a short-term and long-term basis. However, White Mountains can provide no assurance that, if needed, it would be able to obtain additional debt or equity financing on satisfactory terms, if at all. It is possible that, in the future, one or more of the rating agencies may lower White Mountains’s existing ratings. If one or more of its ratings were lowered, White Mountains could incur higher borrowing costs on future borrowings, and its ability to access the capital markets could be impacted. Covenant Compliance As of December 31, 2025, White Mountains was in compliance, in all material respects, with all of the covenants under its debt instruments. 82 Contractual Obligations and Commitments The following table presents White Mountains’s material contractual obligations and commitments as of December 31, 2025: Millions Due in Less Than One Year Due in Two to Three Years Due in Four to Five Years Due After Five Years Total Loss and LAE reserves (1) $ 935.6 $ 958.6 $ 334.0 $ 266.4 $ 2,494.6 Debt 8.1 45.1 173.3 625.6 852.1 Interest on debt 47.3 123.2 114.4 232.0 516.9 Long-term incentive compensation 88.9 121.7 17.6 — 228.2 Ark’s contingent consideration (2) 328.3 — — — 328.3 Redeemable noncontrolling interests (3) — 131.5 — — 131.5 Operating leases 9.2 18.4 16.6 47.6 91.8 Total contractual obligations and commitments $ 1,417.4 $ 1,398.5 $ 655.9 $ 1,171.6 $ 4,643.4 (1) Represents expected future cash outflows resulting from loss and LAE payments. The amounts presented are gross of reinsurance recoverables on unpaid losses of $508 as of December 31, 2025. (2) See “Contingent Consideration Liabilities” in Note 1 — “Basis of Presentation and Significant Accounting Policies” on page F-18. (3) See “Redeemable Noncontrolling Interests” in Note 13 — “Common Shareholders’ Equity and Noncontrolling Interests” on page F-68. The long-term incentive compensation balances included in the table above include amounts payable for performance shares. Exact amounts to be paid for performance shares cannot be predicted with certainty, as the ultimate amounts of these liabilities are based on the future performance of White Mountains and the market price of the Company’s common shares at the time the payments are made. The estimated payments reflected in the table are based on current accrual factors (including performance relative to targets and common share price) and assume that all outstanding balances were 100% vested as of December 31, 2025. There are no provisions within White Mountains’s operating lease agreements that would trigger acceleration of future lease payments. White Mountains does not finance its operations through the securitization of its trade receivables, through special purpose entities or through synthetic leases. Further, White Mountains has not entered into any material arrangements requiring it to guarantee payment of third-party debt or lease payments or to fund losses of an unconsolidated special purpose entity. White Mountains also has future binding commitments to fund certain other long-term investments. These commitments, which totaled approximately $176 million as of December 31, 2025, do not have fixed funding dates and are therefore excluded from the table above. Share Repurchase Programs The Company’s Board of Directors has authorized the Company to repurchase its common shares from time to time, subject to market conditions. Shares may be repurchased on the open market or through privately negotiated transactions. The repurchase authorizations do not have a stated expiration date. As of December 31, 2025, White Mountains may repurchase an additional 269,594 shares under these Board authorizations. In addition, from time to time White Mountains has also repurchased its common shares through self-tender offers that were separately authorized by its Board of Directors. The following table presents common shares repurchased by the Company as well as the average price per share as a percent of December 31, 2025 book value per share and market value per share. Average Price Per Average Price Per Share as % of Share as % of Average December 31, 2025 December 31, 2025 Shares Cost Price Book Value Market Value Year Ended Repurchased (Millions) Per Share Per Share Per Share December 31, 2025 100,581 $ 202.5 $ 2,013.67 92% 97% December 31, 2024 5,269 $ 7.9 $ 1,505.01 69% 72% . December 31, 2023 24,165 $ 32.7 $ 1,354.88 62% 65% 83 Cash Flows Detailed information concerning White Mountains’s cash flows during 2025, 2024 and 2023 follows: Cash flows from operations for the years ended 2025, 2024 and 2023 Net cash flows provided from operations was $551 million, $587 million and $404 million for the years ended December 31, 2025, 2024 and 2023. The decrease in cash provided from operations in 2025 was driven primarily by higher deployments at Kudu and an increase in cash outflows from Other Operations, partially offset by an increase in cash provided from operations at Ark/WM Outrigger, HG Global and Bamboo. The increase in cash provided from operations in 2024 was driven primarily by cash provided from operations at Ark/WM Outrigger Re, Kudu and Bamboo. As of December 31, 2025, the Company and its intermediate holding companies had $975 million of net unrestricted cash, short-term investments and fixed maturity investments, $231 million of MediaAlpha common stock, $31 million of common equity securities and $294 million of private equity funds and hedge funds, ILS funds and certain unconsolidated entities. Cash flows from investing and financing activities for the year ended December 31, 2025 Financing and Other Capital Activities During 2025, the Company declared and paid a $3 million cash dividend to its common shareholders. During 2025, White Mountains repurchased and retired 100,581 of its common shares for $203 million. The majority of these shares were repurchased through the self-tender offer that White Mountains completed in December 2025, through which it repurchased 64,064 of its common shares at a purchase price of $2,082.60 per share ($2,050.00 excluding expenses) for a total cost of approximately $133 million, including expenses. Of the shares White Mountains repurchased in 2025, 5,097 were to satisfy employee income tax withholding pursuant to employee benefit. During 2025, HG Global received $24 million in cash payments of principal on the BAM Surplus Notes. During 2025, Kudu borrowed $113 million in term loans under the Kudu Credit Facility. During 2025, White Mountains contributed $76 million to Kudu, of which $15 million was used to repurchase certain management equity incentives that were then replaced with new equity incentive units. During 2025, Bamboo borrowed $110 million in term loans under the Bamboo Credit Facility. Acquisitions and Dispositions On April 1, 2025, White Mountains closed on its acquisition of Enterprise Solutions. White Mountains paid $58 million of cash consideration, which included a post-acquisition contribution of $2 million, and Enterprise Solutions borrowed $15 million in new debt as part of the transaction. On July 18, 2025, White Mountains deployed $150 million into BroadStreet through the BroadStreet SPV. On September 2, 2025, White Mountains closed its acquisition of Distinguished. White Mountains paid $225 million of cash consideration, including a post-closing purchase price adjustment of $1 million. In addition, Distinguished borrowed $50 million of incremental debt and utilized $7 million of cash on hand as part of the transaction. On December 5, 2025, White Mountains completed the Bamboo Sale Transaction for net cash proceeds at closing of $848 million. Cash flows from investing and financing activities for the year ended December 31, 2024 Financing and Other Capital Activities During 2024, the Company declared and paid a $3 million cash dividend to its common shareholders. During 2024, White Mountains repurchased and retired 5,269 of its common shares for $8 million, all of which were to satisfy employee income tax withholding pursuant to employee benefit plans. During 2024, Ark repaid the outstanding balance of $30 million and extinguished the Ark 2007 Subordinated Notes. During 2024, Kudu borrowed $35 million in term loans under the Kudu Credit Facility. During the six months ended December 31, 2024, subsequent to BAM’s deconsolidation, HG Global received a $16 million cash payment of principal on the BAM Surplus Notes. BAM received $26 million in MSC during the six months ended June 30, 2024, prior to its deconsolidation. Acquisitions and Dispositions On January 2, 2024, White Mountains completed the acquisition of Bamboo, investing $297 million in equity into Bamboo, which included the contribution of $36 million to retire Bamboo’s legacy credit facility and the contribution of $20 million of primary capital. On May 10, 2024, MediaAlpha completed a secondary offering of 7.6 million shares at $19.00 per share ($18.24 per share net of underwriting fees). In the secondary offering, White Mountains sold 5.0 million shares for net proceeds of $91 million. 84 Cash flows from investing and financing activities for the year ended December 31, 2023 Financing and Other Capital Activities During 2023, the Company declared and paid a $3 million cash dividend to its common shareholders. During 2023, White Mountains repurchased and retired 24,165 of its common shares for $33 million. Of the shares White Mountains repurchased in 2023, 4,629 were to satisfy employee income tax withholding pursuant to employee benefit plans. During 2023, Kudu borrowed $12 million in term loans under the Kudu Credit Facility. During 2023, Kudu repaid $17 million in term loans under the Kudu Credit Facility. Acquisitions and Dispositions On June 28, 2023, White Mountains completed a tender offer to purchase 5.9 million additional shares of MediaAlpha at a purchase price of $10.00 per share for a total cost of $59 million. TRANSACTIONS WITH RELATED PERSONS White Mountains does not have any transactions with related persons to report as of December 31, 2025. NON-GAAP FINANCIAL MEASURES This report includes 12 non-GAAP financial measures that have been reconciled from their most comparable GAAP financial measures. Ark’s tangible book value and tangible capital Ark’s tangible book value is a non-GAAP financial measure derived by adjusting GAAP book value to exclude goodwill, other intangible assets, the related deferred tax liability and the contingent consideration liability. The contingent consideration liability represents the estimated fair value of the additional shares that could be earned by management rollover shareholders if and to the extent that White Mountains achieves certain MOIC return thresholds. If earned, these additional shares would result in a reallocation of economics among Ark’s shareholders, which is reflected in the fair value of the contingent consideration liability recorded by White Mountains, but would have no impact on Ark’s stand-alone book value or tangible book value. White Mountains believes that this non-GAAP financial measure is useful to management and investors in evaluating Ark’s enterprise value. See page 59 for the reconciliation of Ark’s GAAP equity to tangible book value. Ark’s tangible capital is a non-GAAP financial measure derived by adding debt to tangible book value. See page 59 for the reconciliation of Ark’s GAAP equity to tangible capital. Kudu’s EBITDA and adjusted EBITDA Kudu's EBITDA and adjusted EBITDA are non-GAAP financial measures. EBITDA is a non-GAAP financial measure that adds back interest expense on debt, income tax (expense) benefit, depreciation and amortization of other intangible assets to GAAP net income (loss). Adjusted EBITDA is a non-GAAP financial measure that excludes certain other items in GAAP net income (loss) in addition to those added back to calculate EBITDA. The items relate to (i) net realized and unrealized investment gains (losses) on Kudu's Participation Contracts, (ii) non-cash equity-based compensation expense and (iii) transaction expenses. A description of each item follows: •Net realized and unrealized investment gains (losses) - Represents net unrealized investment gains and losses on Kudu’s Participation Contracts, which are recorded at fair value under GAAP, and realized investment gains and losses recorded on Kudu’s Participation Contracts sold during the period. •Non-cash equity-based compensation expense - Represents non-cash expenses related to Kudu’s management compensation that are settled with equity units in Kudu. •Transaction expenses - Represents costs directly related to Kudu’s mergers and acquisitions activity, such as external lawyer, banker, consulting and placement agent fees, which are not capitalized and are expensed under GAAP. White Mountains believes that these non-GAAP financial measures are useful to management and investors in evaluating Kudu’s performance. The reconciliation of Kudu’s GAAP net income (loss) to EBITDA and adjusted EBITDA is included on page 67. 85 Bamboo’s MGA pre-tax income (loss), MGA net income (loss), MGA EBITDA and MGA adjusted EBITDA Bamboo’s MGA pre-tax income (loss), MGA net income (loss), MGA EBITDA and MGA adjusted EBITDA are non-GAAP financial measures. MGA pre-tax income (loss) and MGA net income (loss) are non-GAAP financial measures that exclude the results of the Bamboo Captive, which is consolidated by Bamboo MGA under GAAP, from Bamboo’s consolidated GAAP pre-tax income (loss) and net income (loss). The following table presents the reconciliation from Bamboo’s consolidated GAAP pre-tax income (loss) to MGA pre-tax income (loss): Millions January 1, 2025 - December 5, 2025 Year Ended December 31, 2024 Bamboo’s consolidated GAAP pre-tax income (loss) $ 40.1 $ 32.7 Remove pre-tax (income) loss, Bamboo Captive 1.0 (1.0) MGA pre-tax income (loss) $ 41.1 $ 31.7 MGA EBITDA is a non-GAAP financial measure that adds back interest expense on debt, income tax (expense) benefit, depreciation and amortization of other intangible assets to MGA net income (loss). MGA adjusted EBITDA is a non-GAAP financial measure that excludes certain other items in GAAP net income (loss) in addition to those added back to calculate MGA EBITDA. The items relate to (i) non-cash equity-based compensation expense, (ii) software implementation expenses, (iii) restructuring expenses and (iv) transaction expenses. A description of each item follows: •Non-cash equity-based compensation expense - Represents non-cash expenses related to Bamboo’s management compensation that are settled with equity units in Bamboo. •Software implementation expenses - Represents costs directly related to Bamboo’s implementation of new software. •Restructuring expenses - Represents costs directly related to Bamboo’s corporate restructuring and capital planning activities. •Transaction expenses - Represents costs directly related to transaction activities at Bamboo, which are not capitalized and are expensed under GAAP. White Mountains believes that these non-GAAP financial measures are useful to management and investors in evaluating Bamboo’s performance. See page 69 for the reconciliation of Bamboo’s consolidated GAAP net income (loss) to MGA net income (loss), MGA EBITDA and MGA adjusted EBITDA. Distinguished’s ScaleCo net income (loss), ScaleCo EBITDA and ScaleCo adjusted EBITDA Distinguished’s ScaleCo net income (loss), ScaleCo EBITDA and ScaleCo adjusted EBITDA are non-GAAP financial measures. ScaleCo net income (loss) is a non-GAAP financial measure that excludes the results of the GrowthCo vertical, which is consolidated under GAAP, from Distinguished’s consolidated GAAP net income (loss). ScaleCo EBITDA is a non-GAAP financial measure that adds back interest expense on debt, income tax (expense) benefit, depreciation and amortization of other intangible assets to ScaleCo net income (loss). ScaleCo adjusted EBITDA is a non-GAAP financial measure that excludes certain other items in GAAP net income (loss) in addition to those items added back to calculate ScaleCo EBITDA. The items relate to (i) non-cash equity-based compensation expense and (ii) transaction expenses. A description of each item follows: •Non-cash equity-based compensation expense - Represents non-cash expenses related to Distinguished’s management compensation that are settled with equity units in Distinguished. •Transaction expenses - Represents costs directly related to transaction activities at Distinguished, which are not capitalized and are expensed under GAAP. White Mountains believes that these non-GAAP financial measures are useful to management and investors in evaluating Distinguished’s performance. White Mountains also believes that excluding the results of the GrowthCo vertical, which Distinguished views as an investment in start-up programs, is useful to understanding the performance of Distinguished’s established programs. See page 71 for the reconciliation of Distinguished’s consolidated GAAP net income (loss) to ScaleCo net income (loss), ScaleCo EBITDA and ScaleCo adjusted EBITDA. Total consolidated portfolio return excluding MediaAlpha Total consolidated portfolio return excluding MediaAlpha is a non-GAAP financial measure that removes the net investment income and net realized and unrealized investment gains (losses) from White Mountains’s investment in MediaAlpha. White Mountains believes this non-GAAP measure to be useful to management and investors by showing the underlying performance of White Mountains’s investment portfolio without regard to White Mountains’s investment in MediaAlpha. 86 The following table presents return reconciliations from GAAP to the reported percentages: Year Ended December 31, 2025 2024 2023 Total consolidated portfolio return 9.1 % 6.9 % 11.4 % Remove MediaAlpha (0.2) (0.4) — Total consolidated portfolio return excluding MediaAlpha 8.9 % 6.5 % 11.4 % CRITICAL ACCOUNTING ESTIMATES Management’s Discussion and Analysis of Financial Condition and Results of Operations discuss the Company’s consolidated financial statements, which have been prepared in accordance with GAAP. The financial statements presented herein include all adjustments considered necessary by management to fairly present the financial condition, results of operations and cash flows of White Mountains. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Certain of these estimates are considered critical in that they involve a higher degree of judgment and are subject to a significant degree of variability. On an ongoing basis, management evaluates its estimates and bases its estimates on historical experience and on various other factors that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. 1. Fair Value Measurements General White Mountains records certain assets and liabilities at fair value in its consolidated financial statements. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants (an exit price) at a particular measurement date. Fair value measurements are categorized into a hierarchy that distinguishes between inputs based on market data from independent sources (observable inputs) and a reporting entity’s internal assumptions based upon the best information available when external market data is limited or unavailable (unobservable inputs). Quoted prices in active markets for identical assets have the highest priority (“Level 1”), followed by observable inputs other than quoted prices including prices for similar but not identical assets or liabilities (“Level 2”) and unobservable inputs, including the reporting entity’s estimates of the assumptions that market participants would use, having the lowest priority (“Level 3”). The valuation of assets and liabilities measured at fair value requires management to make estimates and apply judgment to matters that may carry a significant degree of uncertainty. In determining its estimates of fair value, White Mountains uses a variety of valuation approaches and inputs. Whenever possible, White Mountains estimates fair value using valuation methods that maximize the use of quoted market prices or other observable inputs. Where appropriate, assets and liabilities measured at fair value have been adjusted for the effect of counterparty credit risk. Fair value estimates for instruments that trade infrequently and have few or no quoted market prices or other observable inputs are classified as Level 3 measurements. The determination of the fair value of these Level 3 instruments involves significant management judgment and the use of valuation analyses and unobservable inputs that are inherently subjective and uncertain. These unobservable inputs reflect White Mountains’s assumptions of what market participants would use in valuing the instrument. See Item 1A. Risk Factors, “Our investment portfolio includes securities that do not have readily observable market prices. We use valuation methodologies that are inherently subjective and uncertain to value these securities. The values of securities established using these methodologies may never be realized, which could materially adversely affect our results of operations and financial condition.” on page 36. See Note 1 — “Basis of Presentation and Significant Accounting Policies” on page F-8 for White Mountains’s accounting policies for investment securities. As of December 31, 2025, White Mountains’s most significant assets classified as Level 3 measurements include the BAM Surplus Notes, Kudu’s Participation Contracts, the Bamboo SPV and PassportCard/DavidShield. 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” on page F-19. 87 BAM Surplus Notes As of December 31, 2025, the fair value of the BAM Surplus Notes was $339 million. On a quarterly basis, White Mountains values the BAM Surplus Notes using a discounted cash flow analysis. The discounted cash flow analysis used to fair value the BAM Surplus Notes depends on key inputs, such as projections of future revenues and earnings for BAM, expected payments on the BAM Surplus Notes through maturity and a discount rate to reflect time value and related uncertainty of the repayment pattern. The expected payments on the BAM Surplus Notes are based on management judgment, considering current performance, budgets and projected future results. These expected payments depend on BAM’s ability to generate excess cash flows from its operations, driven primarily by assumptions regarding future trends for the issuance of municipal bonds, interest rates, credit spreads, insured market penetration, competitive activity in the market for municipal bond insurance and other factors affecting the demand for and pricing of BAM’s municipal bond insurance, as well as BAM’s investment returns. The discount rate considers comparably-rated companies and instruments, adjusted for risks specific to BAM and the BAM Surplus Notes. As of December 31, 2025, White Mountains concluded that a discount rate of 8.05% was appropriate for the valuation of the BAM Surplus Notes. When making its fair value selection, which is within a range of reasonable values derived from the discounted cash flow analysis, White Mountains considers all available information, facts and circumstances specific to BAM’s business and industry and any infrequent or unusual results for the period. See Item 1A. Risk Factors, “We may be subject to volatility from the valuation of the BAM Surplus Notes, which could materially adversely affect our results of operations and financial condition.” on page 33. With a discounted cash flow analysis, small changes to key inputs may result in significant changes to fair value. The following table presents the estimated effect on the fair value of the BAM Surplus Notes as of December 31, 2025, resulting from changes to the discount rate used in the discounted cash flow analysis: Millions Discount Rate 6.0% 7.0% 8.05% 9.0% 10.0% BAM Surplus Notes, at fair value $ 398 $ 369 $ 339 $ 312 $ 283 Kudu’s Participation Contracts As of December 31, 2025, Kudu has a portfolio of Participation Contracts with a total fair value of $1,285 million. On a quarterly basis, White Mountains fair values each of Kudu’s Participation Contracts, typically using a discounted cash flow analysis. The discounted cash flow analyses used to fair value Kudu’s Participation Contracts include key inputs, such as projections of future revenues and earnings of Kudu’s managers, a discount rate and a terminal cash flow exit multiple. The expected future cash flows are based on management judgment, considering current performance, budgets and projected future results. The discount rates reflect the weighted average cost of capital, considering comparable public company data and adjusted for risks specific to the business and industry. The terminal cash flow exit multiple is generally based on expectations of annual cash flow to Kudu from each of its managers in the terminal year of the discounted cash flow analysis. In determining fair value, White Mountains considers factors for each of Kudu’s managers, such as performance of products and vehicles, expected asset growth rates, new fund launches, fee rates by product, capacity constraints, operating cash flows and other qualitative factors, including the assessment of key personnel. The inputs to each discounted cash flow analysis vary depending on the nature of each of Kudu’s managers. As of December 31, 2025, White Mountains concluded that pre-tax discount rates in the range of 16% to 25% and terminal cash flow exit multiples in the range of 7 to 22 times were appropriate for the valuations of Kudu’s Participation Contracts. When making its fair value selections, which are within a range of reasonable values derived from the discounted cash flow analysis, White Mountains considers all available information, including any relevant market multiples and multiples implied by recent transactions, facts and circumstances specific to Kudu’s managers and any infrequent or unusual results for the period. 88 With a discounted cash flow analysis, small changes to key inputs may result in significant changes to fair value. The following table presents the estimated effect on the fair value of Kudu’s Participation Contracts as of December 31, 2025, resulting from changes in key inputs to the discounted cash flow analysis, including discount rates and terminal cash flow exit multiples: Millions Discount Rate(1) Terminal Cash Flow Exit Multiple -2% -1% 16% - 25% +1% +2% +2 $ 1,554 $ 1,457 $ 1,368 $ 1,283 $ 1,209 +1 $ 1,504 $ 1,412 $ 1,326 $ 1,245 $ 1,174 7x to 22x $ 1,455 $ 1,366 $ 1,285 $ 1,207 $ 1,139 -1 $ 1,406 $ 1,321 $ 1,243 $ 1,169 $ 1,104 -2 $ 1,356 $ 1,276 $ 1,202 $ 1,136 $ 1,075 (1) 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. PassportCard/DavidShield As of December 31, 2025, the fair value of White Mountains’s investment in PassportCard/DavidShield was $170 million. On a quarterly basis, White Mountains values its investment in PassportCard/DavidShield using a discounted cash flow analysis. The discounted cash flow analysis used to fair value PassportCard/DavidShield includes key inputs, such as projections of future revenues and earnings, a discount rate and a terminal revenue growth rate. The expected future cash flows are based on management judgment, considering current performance, budgets and projected future results. The discount rate reflects the weighted average cost of capital, considering comparable public company data and adjusted for risks specific to the business and industry. The terminal revenue growth rate is based on company, industry and macroeconomic expectations of perpetual revenue growth subsequent to the end of the discrete period in the discounted cash flow analysis. As of December 31, 2025, White Mountains concluded that an after-tax discount rate of 24% and a terminal revenue growth rate of 4% were appropriate for the valuation of its investment in PassportCard/DavidShield. When making its fair value selection, which is within a range of reasonable values derived from the discounted cash flow analysis, White Mountains considers all available information, including any relevant market multiples and multiples implied by recent transactions, facts and circumstances specific to PassportCard/DavidShield’s businesses and industries and any infrequent or unusual results for the period. With a discounted cash flow analysis, small changes to key inputs may result in significant changes to fair value. The following table presents the estimated effect on the fair value of White Mountains’s investment in PassportCard/DavidShield as of December 31, 2025, resulting from changes in key inputs to the discounted cash flow analysis, including the discount rate and terminal revenue growth rate: Millions Discount Rate Terminal Revenue Growth Rate 22% 23% 24% 25% 26% 5.0% $ 200 $ 186 $ 173 $ 162 $ 152 4.0% $ 195 $ 182 $ 170 $ 159 $ 150 3.0% $ 191 $ 179 $ 167 $ 157 $ 148 89 2. Ark’s Loss and LAE Reserves General Ark establishes loss and LAE reserves that are estimates of amounts needed to pay claims and related expenses in the future for insured events that have already occurred. The process of estimating loss and LAE reserves involves a considerable degree of judgment by management and, as of any given date, is inherently uncertain. See Note 5 — “Loss and Loss Adjustment Expense Reserves” on page F-36 for a description of Ark’s loss and LAE reserves and actuarial methods. Ark performs an actuarial review of its recorded loss and LAE reserves each quarter, using several generally accepted actuarial methods to evaluate its loss reserves, each of which has its own strengths and weaknesses. Management bases its level of reliance on a particular method based on the facts and circumstances at the time the reserve estimates are made. As part of Ark’s quarterly actuarial review, Ark compares the previous quarter’s projections of incurred, paid and case reserve activity, including amounts incurred but not reported, to actual amounts experienced in the quarter. Differences between previous estimates and actual experience are evaluated to determine whether a given actuarial method for estimating loss and LAE reserves should be relied upon to a greater or lesser extent than it had been in the past. While some variance is expected each quarter due to the inherent uncertainty in estimating loss and LAE reserves, persistent or large variances would indicate that prior assumptions and/or reliance on certain actuarial methods may need to be revised going forward. Upon completion of each quarterly review, Ark selects indicated loss and LAE reserve levels based on the results of the relevant actuarial methods, which are the primary consideration in determining management’s best estimate of required loss and LAE reserves. However, in making its best estimate, management also considers other qualitative factors that may lead to a difference between held reserves and actuarially indicated reserve levels. Typically, these qualitative factors are considered when management and Ark’s actuaries conclude that there is insufficient historical incurred and paid loss information or that there is particular uncertainty about whether trends included in the historical incurred and paid loss information are likely to repeat in the future. Such qualitative factors include, among others, recent entry into new markets or new products, improvements in the claims department that are expected to lessen future ultimate loss costs, legal and regulatory developments, inflation, climate change or other uncertainties that may arise. The process of establishing loss and LAE reserves, including amounts incurred but not reported, is complex and imprecise, as it must consider many variables that are subject to the outcome of future events. As a result, informed subjective estimates and judgments as to Ark’s ultimate exposure to losses are an integral component of the loss and LAE reserving process. Ark categorizes and tracks insurance and reinsurance reserves by “reserving class of business” for each underwriting office, London and Bermuda, and then aggregates the reserving classes by line of business, which are summarized herein as property and accident & health, marine & energy, specialty, casualty-active and casualty-runoff. Ark regularly reviews the appropriateness of its loss and LAE reserves at the reserving class of business level, considering a variety of trends that impact the ultimate settlement of claims for the subsets of claims in each particular reserving class. Loss and LAE are categorized by the year in which the policy is underwritten (the year of account, or underwriting year) for purposes of Ark’s claims management and estimation of the ultimate loss and LAE reserves. For purposes of Ark’s reporting under GAAP, loss and LAE are categorized by the accident year. Loss and LAE Reserves by Line of Business The following table summarizes Ark’s loss and LAE reserves, net of reinsurance recoverables on unpaid losses, as of December 31, 2025: December 31, 2025 Millions Case IBNR Total Property and Accident & Health $ 236.8 $ 341.5 $ 578.3 Marine & Energy 146.4 422.6 569.0 Specialty 96.8 411.4 508.2 Casualty-Active 36.0 194.6 230.6 Casualty-Runoff 28.2 28.9 57.1 Total loss and LAE reserves, net of reinsurance recoverables $ 544.2 $ 1,399.0 $ 1,943.2 90 For loss and LAE reserves as of December 31, 2025, Ark considers that the impact of the various reserving factors, as described in Note 5 — “Loss and Loss Adjustment Expense Reserves” on page F-36, on future paid losses would be similar to the impact of those factors on historical paid losses. The major causes of material uncertainty (i.e., reserving factors) generally will vary for each line of business, as well as for each separately analyzed reserving class of business within the line of business. Also, reserving factors can have offsetting or compounding effects on estimated loss and LAE reserves. In most cases, it is not possible to measure the effect of a single reserving factor and construct a meaningful sensitivity expectation. Actual results will likely vary from expectations for each of these assumptions, resulting in an ultimate claim liability that is different from that being estimated currently. Additional causes of material uncertainty exist in most product lines and may impact the types of claims that could occur within a particular line of business or reserving class of business. Examples where reserving factors within a line of business or reserving class of business are subject to change include changing types of insureds (e.g., size of account, industry insured, jurisdiction), changing underwriting standards or changing policy provisions (e.g., deductibles, policy limits, endorsements). Ark Loss and LAE Development See Note 5 — “Loss and Loss Adjustment Expense Reserves” on page F-36 for prior year loss and LAE development discussions for the year ended December 31, 2025. Range of Reserves The following table shows the recorded loss and LAE reserves and the high and low ends of Ark’s range of reasonable loss and LAE reserve estimates, net of reinsurance recoverables on unpaid losses, as of December 31, 2025. See Note 5 — “Loss and Loss Adjustment Expense Reserves” on page F-36 for a description of Ark’s loss and LAE reserves and actuarial methods. December 31, 2025 Millions Low Recorded High Total loss and LAE reserves, net of reinsurance recoverables $1,510.2 $1,943.2 $2,023.8 The recorded reserves represent management's best estimate of unpaid loss and LAE reserves. Management’s best estimate of reserves is in the upper portion of the actuarial range of estimates in response to potential volatility in the actuarial indications and estimates for large claims. Ark uses the results of several different standard actuarial methods to develop its best estimate of ultimate loss and LAE reserves. On an annual basis, Ark uses an independent external actuary to provide actuarial opinions on the reasonableness of loss and LAE reserves for its operating subsidiaries. Ark uses the independent actuarial review solely to corroborate Ark’s recorded loss and LAE reserves. The result of the independent actuarial review indicated that Ark’s net recorded loss and LAE reserves fall within the range noted above. Although Ark believes its loss and LAE reserves are reasonably stated, ultimate losses may deviate, perhaps materially, from the recorded reserve amounts and could be above the high end of the range of actuarial projections. This is because ranges are developed based on known events as of the valuation date, whereas the ultimate disposition of losses is subject to the outcome of events and circumstances that may be unknown as of the valuation date. 91 Sensitivity Analysis Below is a discussion of possible variations from current estimates of loss and LAE reserves due to changes in certain key assumptions. Each of the impacts described below is estimated individually, without consideration for any correlation among key assumptions. Further, there is uncertainty around other assumptions not explicitly quantified in the discussion below. Therefore, it would be inappropriate to take each of the amounts described below and add them together in an attempt to estimate volatility for Ark’s reserves in total. It is important to note that the volatilities and variations discussed below are not meant to be worst-case scenarios or an all-inclusive list, and therefore it is possible that future volatilities and variations may be more than amounts discussed below. •Sustained elevated levels of inflation: Elevated levels of economic inflation have been observed since 2021. While most global economies are seeing these elevated levels begin to decline, inflation continues to be a key focus point for central bank policy. The extent to which inflation will impact the ultimate cost of insurance claims remains uncertain, particularly in the casualty lines of business with key social inflation drivers being court awards, changes in technology and the legal environment. For example, a hypothetical increase in inflation rates by 4% per annum would increase the recorded loss and LAE reserves, net of reinsurance recoverables on unpaid losses, for the casualty reserving lines of business by approximately $20 million, or approximately 7% of the recorded casualty loss and LAE reserves of $288 million. •Catastrophe losses: The years 2017 through 2025 have been active for major loss events, including natural catastrophes. As time has passed, the emerging claims information for major loss events has been better than expected. As of December 31, 2025, Ark has recorded $230 million of loss and LAE reserves, net of reinsurance recoverables on unpaid losses, for major loss events, of which $171 million is held as IBNR reserves. Some, but perhaps not all, of the IBNR reserves may be needed to handle adverse reporting from clients. •Conflict in Ukraine and Russia: The conflict in Ukraine and Russia has and will continue to have a significant impact on the insurance industry. Recent U.K. High Court rulings on leasing claims provided more certainty on coverages related to aviation hull war risk claims, but there are additional court cases to be decided and there is uncertainty as to how claims will be presented to reinsurers. For the year ended December 31, 2025, Ark recognized $91 million of unfavorable loss reserve development related to aviation losses from the conflict in Ukraine and Russia, driven by the U.K. High Court rulings. This is a complex loss event that will continue to be litigated and negotiated in the future. As such, there remains uncertainty with respect to the ultimate impact to both insurers and reinsurers. 92 Loss and LAE Reserve Summary The following table summarizes the loss and LAE reserve activity of Ark’s insurance and reinsurance subsidiaries for the year ended December 31, 2025. The amounts in the table include balances ceded by Ark to WM Outrigger Re, which eliminate in White Mountains’s consolidated financial statements. Millions Year Ended December 31, 2025 Gross beginning balance $ 2,127.5 Less: beginning reinsurance recoverable on unpaid losses (466.2) Net loss and LAE reserves 1,661.3 Loss and LAE incurred relating to: Current year losses 925.1 Prior year losses (106.3) Net incurred loss and LAE 818.8 Loss and LAE paid relating to: Current year losses (187.9) Prior year losses (370.1) Net paid loss and LAE (558.0) Foreign currency translation and other adjustments to loss and LAE reserves 21.1 Net ending balance 1,943.2 Plus: ending reinsurance recoverable on unpaid losses 537.8 Gross ending balance $ 2,481.0 During the year ended December 31, 2025, Ark experienced $106 million of net favorable prior year loss reserve development, driven primarily by the property and accident & health ($85 million) and specialty ($27 million) reserving lines of business, partially offset by net unfavorable development in the marine & energy ($5 million) and casualty-active ($4 million) reserving lines of business. For property and accident & health, the net favorable prior year loss reserve development was driven primarily by positive claims experience for the 2024 and 2023 accident years. For specialty, the net favorable prior year loss reserve development was driven primarily by positive claims experience for the 2023 accident year, partially offset by negative claims experience for the 2022 and 2024 accident years. In addition, the net favorable prior year loss reserve development for specialty includes $91 million of unfavorable development related to aviation losses from the conflict in Ukraine and Russia resulting from the 2025 U.K. High Court rulings on leasing claims. 93 The following table summarizes the unpaid loss and LAE reserves, net of reinsurance recoverables on unpaid losses, for each of Ark’s major reserving lines of business as of December 31, 2025. The amounts in the table include balances ceded by Ark to WM Outrigger Re, which eliminate in White Mountains’s consolidated financial statements. Millions As of December 31, 2025 Property and Accident & Health $ 578.3 Marine & Energy 569.0 Specialty 508.2 Casualty-Active 230.6 Casualty-Runoff 57.1 Unpaid loss and LAE reserves, net of reinsurance recoverables on unpaid losses 1,943.2 Plus: Reinsurance recoverables on unpaid losses Property and Accident & Health 171.9 Marine & Energy 208.9 Specialty 44.4 Casualty-Active 113.0 Casualty-Runoff (.4) Total Reinsurance recoverables on unpaid losses 537.8 Total unpaid loss and LAE reserves $ 2,481.0 The following five tables cover each of Ark’s property and accident & health, marine & energy, specialty, casualty-active and casualty-runoff reserving lines of business and are net of reinsurance. Each of the five tables includes three sections as follows: The top section of the table presents, for each of the previous ten accident years, (1) cumulative total undiscounted incurred loss and LAE as of each of the previous ten year-end evaluations, (2) total IBNR plus expected development on reported claims as of December 31, 2025 and (3) the cumulative number of reported claims as of December 31, 2025. The middle section of the table presents cumulative paid loss and LAE for each of the previous ten accident years as of each of the previous ten year-end evaluations. Also included in this section is a calculation of the loss and LAE reserves as of December 31, 2025, which is then included in the reconciliation to the consolidated balance sheet presented above. The total unpaid loss and LAE reserves as of December 31, 2025 is calculated as the cumulative incurred loss and LAE from the top section less the cumulative paid loss and LAE from the middle section, plus any outstanding liabilities from accident years prior to 2015. The bottom section of the table is supplementary information about the average historical claims duration as of December 31, 2025. It shows the weighted average annual percentage payout of incurred loss and LAE by accident year as of each age. For example, the first column is calculated as the incremental paid loss and LAE in the first calendar year for each given accident year (e.g., calendar year 2025 for accident year 2025, calendar year 2024 for accident year 2024) divided by the cumulative incurred loss and LAE as of December 31, 2025 for that accident year. The resulting ratios are weighted using cumulative incurred loss and LAE as of December 31, 2025. 94 Property and Accident & Health $ in Millions Incurred Loss and LAE, Net of Reinsurance For the Years Ended December 31, As of December 31, 2025 Accident Year 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 Total IBNR plus expected development on reported claims Cumulative number of reported claims 2016 $ 22.7 $ 17.8 $ 18.6 $ 18.7 $ 18.7 $ 18.9 $ 18.8 $ 18.8 $ 18.8 $ 18.8 $ .2 3,434 2017 31.6 38.3 45.8 44.8 43.4 42.9 44.3 43.9 43.3 15.6 4,629 2018 41.4 47.8 49.7 47.4 47.4 47.0 47.0 49.0 2.7 4,293 2019 34.6 31.7 27.4 24.2 23.5 23.2 21.5 .5 4,030 2020 78.1 76.3 75.3 79.1 81.0 84.8 6.0 4,664 2021 173.0 156.8 168.9 171.5 169.7 8.1 3,533 2022 245.7 269.6 280.0 281.9 9.0 4,100 2023 216.9 178.6 130.4 20.8 3,688 2024 364.8 324.6 106.4 4,495 2025 394.1 171.7 3,899 Total $ 1,518.1 Property and Accident & Health Millions Cumulative Paid Loss and LAE, Net of Reinsurance For the Years Ended December 31, Accident Year 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2016 $ 8.6 $ 13.3 $ 16.6 $ 17.0 $ 17.1 $ 17.4 $ 18.0 $ 18.2 $ 18.4 $ 18.4 2017 17.0 26.1 31.9 33.1 29.9 27.7 25.9 28.7 29.3 2018 15.8 32.7 40.6 40.6 41.4 43.4 44.2 45.2 2019 6.9 17.0 18.6 18.8 19.6 20.9 19.9 2020 11.4 34.5 47.5 56.3 67.4 72.4 2021 31.0 87.5 132.3 145.6 150.9 2022 71.7 194.5 232.0 250.2 2023 20.2 53.8 78.5 2024 55.4 134.6 2025 142.8 Total 942.2 All outstanding liabilities before 2016, net of reinsurance 2.4 Loss and LAE reserves, net of reinsurance $ 578.3 Property and Accident & Health Average Annual Percentage Payout of Incurred Loss and LAE by Age, Net of Reinsurance Years 1 2 3 4 5 6 7 8 9 10 27.4% 31.9% 18.4% 6.4% 2.9% 1.9% 0.4% 0.9% 0.2% 0.1% 95 Marine & Energy $ in Millions Incurred Loss and LAE, Net of Reinsurance For the Years Ended December 31, As of December 31, 2025 Accident Year 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 Total IBNR plus expected development on reported claims Cumulative number of reported claims 2016 $ 23.8 $ 20.0 $ 16.0 $ 14.9 $ 14.6 $ 15.2 $ 14.5 $ 14.0 $ 13.7 $ 13.8 $ — 3,776 2017 26.5 19.7 17.9 17.3 16.9 16.0 16.3 16.4 16.4 .2 4,141 2018 26.2 20.6 18.1 18.5 18.0 18.4 17.4 17.0 .2 3,245 2019 24.2 22.0 22.1 21.9 22.3 21.6 21.8 .4 2,413 2020 30.4 27.7 29.1 27.9 27.6 27.6 .8 1,594 2021 87.7 70.5 68.4 75.6 79.8 3.8 1,530 2022 150.8 154.9 157.5 218.6 56.8 2,083 2023 198.6 189.9 123.2 36.8 2,341 2024 243.3 248.1 138.4 2,195 2025 235.3 184.9 1,618 Total $ 1,001.6 Marine & Energy Millions Cumulative Paid Loss and LAE, Net of Reinsurance For the Years Ended December 31, Accident Year 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2016 $ 5.6 $ 10.2 $ 12.9 $ 13.3 $ 13.4 $ 14.1 $ 13.8 $ 13.8 $ 13.8 $ 13.8 2017 5.2 11.3 13.1 14.4 14.4 14.3 14.3 14.6 15.9 2018 2.7 12.9 14.6 15.3 16.0 15.9 16.1 16.3 2019 3.4 10.9 12.9 14.7 15.7 18.4 19.3 2020 3.2 12.9 16.3 18.9 22.4 23.2 2021 6.4 24.9 38.9 52.7 64.4 2022 12.3 66.7 98.6 145.5 2023 10.6 42.7 61.3 2024 21.4 60.1 2025 19.4 Total 439.2 All outstanding liabilities before 2016, net of reinsurance 6.6 Loss and LAE reserves, net of reinsurance $ 569.0 Marine & Energy Average Annual Percentage Payout of Incurred Loss and LAE by Age, Net of Reinsurance Years 1 2 3 4 5 6 7 8 9 10 12.1% 27.1% 17.3% 12.1% 6.4% 6.5% 0.5% 0.4% 0.1% 0.1% 96 Specialty $ in Millions Incurred Loss and LAE, Net of Reinsurance For the Years Ended December 31, As of December 31, 2025 Accident Year 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 Total IBNR plus expected development on reported claims Cumulative number of reported claims 2016 $ 18.5 $ 14.5 $ 11.1 $ 11.4 $ 12.0 $ 12.0 $ 9.1 $ 8.6 $ 12.5 $ 12.2 $ .2 1,936 2017 18.3 13.2 12.3 11.8 11.9 10.9 10.6 11.2 11.1 — 2,201 2018 14.7 16.6 17.0 16.2 15.1 15.9 16.9 17.5 .9 2,129 2019 22.1 19.8 18.9 25.9 30.1 20.0 26.8 .7 2,396 2020 24.5 23.5 19.3 20.4 17.3 17.7 1.3 2,028 2021 71.8 63.0 51.8 44.0 41.7 6.6 1,735 2022 181.9 178.5 172.6 179.6 58.3 1,577 2023 216.6 199.4 153.4 41.3 1,734 2024 223.2 231.3 133.2 1,798 2025 226.8 169.4 1,831 Total $ 918.1 Specialty Millions Cumulative Paid Loss and LAE, Net of Reinsurance For the Years Ended December 31, Accident Year 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2016 $ 3.2 $ 8.0 $ 9.2 $ 10.0 $ 10.4 $ 10.5 $ 8.7 $ 8.4 $ 11.8 $ 11.8 2017 3.3 6.8 8.6 8.8 8.8 9.5 9.3 9.9 9.9 2018 2.9 8.5 10.2 10.6 12.0 13.2 14.4 14.8 2019 5.0 7.2 7.6 18.5 25.2 17.7 19.8 2020 5.4 11.0 13.4 18.8 18.5 19.2 2021 5.1 24.1 35.8 34.6 35.3 2022 16.1 62.5 84.9 113.2 2023 19.2 76.3 109.1 2024 28.9 53.8 2025 24.1 Total 411.0 All outstanding liabilities before 2016, net of reinsurance 1.1 Loss and LAE reserves, net of reinsurance $ 508.2 Specialty Average Annual Percentage Payout of Incurred Loss and LAE by Age, Net of Reinsurance Years 1 2 3 4 5 6 7 8 9 10 18.2% 26.8% 13.2% 8.7% 6.3% 2.5% 2.1% 1.8% (1.2)% 1.0% 97 Casualty-Active $ in Millions Incurred Loss and LAE, Net of Reinsurance For the Years Ended December 31, As of December 31, 2025 Accident Year 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 Total IBNR plus expected development on reported claims Cumulative number of reported claims 2016 $ 8.8 $ 8.3 $ 8.9 $ 9.0 $ 9.1 $ 9.2 $ 9.2 $ 10.1 $ 11.8 $ 11.9 $ .4 1,606 2017 11.6 11.7 10.8 9.3 9.1 10.5 10.7 10.9 10.6 .7 1,693 2018 12.9 13.3 11.1 10.9 8.6 9.2 9.4 10.5 .9 1,175 2019 14.8 13.7 12.3 10.6 11.4 13.0 14.4 1.4 1,062 2020 13.5 12.1 10.9 9.2 8.8 9.5 1.7 731 2021 21.4 22.4 16.6 16.3 21.7 4.1 1,050 2022 33.0 38.1 34.7 17.3 9.8 1,774 2023 61.0 65.9 57.1 39.4 2,234 2024 60.0 82.0 71.9 2,171 2025 68.2 63.4 1,723 Total $ 303.2 Casualty-Active Millions Cumulative Paid Loss and LAE, Net of Reinsurance For the Years Ended December 31, Accident Year 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2016 $ .2 $ 1.0 $ 2.3 $ 4.0 $ 4.6 $ 5.3 $ 6.5 $ 8.1 $ 9.7 $ 10.3 2017 .8 1.7 2.8 3.4 4.2 5.7 7.5 8.3 9.1 2018 .3 1.4 3.5 4.3 4.3 6.2 7.1 8.0 2019 .3 1.4 2.3 3.0 5.7 8.3 10.2 2020 .5 1.0 2.0 3.3 5.3 6.0 2021 .5 .9 3.1 9.6 12.6 2022 .5 1.6 2.5 3.6 2023 .9 5.6 10.8 2024 1.9 4.6 2025 1.0 Total 76.2 All outstanding liabilities before 2016, net of reinsurance 3.6 Loss and LAE reserves, net of reinsurance $ 230.6 Casualty-Active Average Annual Percentage Payout of Incurred Loss and LAE by Age, Net of Reinsurance Years 1 2 3 4 5 6 7 8 9 10 3.8% 7.5% 11.4% 12.9% 10.0% 11.2% 7.2% 5.1% 4.2% 3.4% 98 Casualty-Runoff $ in Millions Incurred Loss and LAE, Net of Reinsurance For the Years Ended December 31, As of December 31, 2025 Accident Year 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 Total IBNR plus expected development on reported claims Cumulative number of reported claims 2016 $ 32.6 $ 32.3 $ 40.5 $ 38.6 $ 38.9 $ 38.6 $ 37.7 $ 37.5 $ 37.5 $ 38.1 $ 1.9 2,156 2017 30.7 34.0 31.5 32.1 31.6 29.9 28.3 28.5 27.9 2.0 1,606 2018 33.6 28.2 27.3 26.6 26.2 28.0 27.8 28.2 2.9 1,284 2019 26.5 23.3 23.4 24.9 23.6 23.7 22.5 4.2 976 2020 15.9 12.3 13.9 10.9 9.5 9.2 2.3 573 2021 10.5 7.0 5.5 4.5 3.9 1.5 284 2022 .8 2.6 2.6 2.3 1.3 80 2023 2.7 3.6 3.1 1.8 40 2024 1.2 1.1 .5 20 2025 .7 — 41 Total $ 137.0 Casualty-Runoff Millions Cumulative Paid Loss and LAE, Net of Reinsurance For the Years Ended December 31, Accident Year 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2016 $ 3.9 $ 10.2 $ 17.7 $ 22.7 $ 25.4 $ 27.8 $ 28.8 $ 31.0 $ 32.5 $ 34.1 2017 3.2 9.4 14.7 18.5 21.4 22.5 22.8 23.5 24.8 2018 3.4 7.4 12.6 14.9 16.3 18.2 21.3 22.7 2019 3.3 5.8 7.8 12.1 15.1 15.9 17.3 2020 .8 1.3 3.1 6.0 6.3 6.5 2021 .5 1.7 1.9 2.3 2.4 2022 .3 .6 .7 .9 2023 .9 1.0 1.1 2024 .5 .5 2025 .6 Total 110.9 All outstanding liabilities before 2016, net of reinsurance 31.0 Loss and LAE reserves, net of reinsurance $ 57.1 Casualty-Runoff Average Annual Percentage Payout of Incurred Loss and LAE by Age, Net of Reinsurance Years 1 2 3 4 5 6 7 8 9 10 8.8% 13.9% 15.3% 14.8% 8.5% 6.7% 5.9% 4.2% 3.2% 2.2% 99 3. Goodwill and Other Intangible Assets As of December 31, 2025, goodwill and other intangible assets recognized in connection with business and asset acquisitions totaled $1,020 million, of which $642 million was attributable to White Mountains’s common shareholders. Under the acquisition method, White Mountains recognizes and measures the assets acquired, including other intangible assets, at their acquisition date fair values. Goodwill represents the excess of the amount paid to acquire a business over the fair value of identifiable net assets at the acquisition date. Goodwill and other intangible assets with indefinite lives are not amortized but rather are evaluated for impairment on an annual basis, or whenever indications of potential impairment exist. In the absence of any indications of potential impairment, the evaluation of goodwill and indefinite-lived intangible assets is performed no later than the interim period in which the anniversary of the acquisition date falls. White Mountains initially evaluates goodwill and indefinite-lived intangible assets using a qualitative approach (step zero) to determine whether it is more likely than not that the implied fair value is greater than the carrying value. If the results of the qualitative evaluation indicate that it is more likely than not that the carrying value of goodwill or the indefinite-lived intangible assets exceeds the implied fair value, White Mountains performs a quantitative analysis to compare the fair value with the carrying value. If the carrying value exceeds the estimated fair value, then an impairment charge is recognized through current period pre-tax income (loss). Other intangible assets with finite lives are initially measured at their acquisition date fair values and subsequently amortized over their economic lives. Finite-lived intangible assets are presented net of accumulated amortization on the balance sheet. Finite-lived intangible assets are reviewed for impairment when events occur or there are changes in circumstances indicating that their carrying value may exceed fair value. An impairment exists when the carrying value of a finite-lived intangible asset exceeds the fair value. During the year ended December 31, 2025, White Mountains performed its periodic reviews for potential impairment and recognized an impairment of goodwill of $9 million and other intangible assets of $1 million related to an Other Operating Business within Other Operations. Impairment charges are presented within general and administrative expenses on the statement of operations. As of December 31, 2025, White Mountains had total goodwill and other intangible assets of $1,020 million, $578 million of which relates to Distinguished and $293 million of which relates to Ark. See Note 4 — “Goodwill and Other Intangible Assets” on page F-34. See Item 1A. Risk Factors, “If we are required to write down goodwill and other intangible assets, it could materially adversely affect our results of operations and financial condition.” on page 29. 100 FORWARD-LOOKING STATEMENTS This report may contain “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. All statements, other than statements of historical facts, included or referenced in this report which address activities, events or developments which White Mountains expects or anticipates will or may occur in the future are forward-looking statements. The words “could”, “will”, “believe”, “intend”, “expect”, “anticipate”, “project”, “estimate”, “predict” and similar expressions are also intended to identify forward-looking statements. These forward-looking statements include, among others, statements with respect to White Mountains’s: •change in book value per share or return on equity; •business strategy; •financial and operating targets or plans; •incurred loss and LAE and the adequacy of its loss and LAE reserves and related reinsurance; •projections of revenues, income (or loss), earnings (or loss) per share, EBITDA, adjusted EBITDA, dividends, market share or other financial forecasts of White Mountains or its businesses; •expansion and growth of its business and operations; and •future capital expenditures. These statements are based on certain assumptions and analyses made by White Mountains in light of its experience and perception of historical trends, current conditions and expected future developments, as well as other factors believed to be appropriate in the circumstances. However, whether actual results and developments will conform to its expectations and predictions is subject to risks and uncertainties that could cause actual results to differ materially from expectations, including: •the risks associated with Item 1A of this Report on Form 10-K; •claims arising from catastrophic events, such as hurricanes, windstorms, earthquakes, floods, wildfires, tornadoes, tsunamis, severe weather, public health crises, terrorist attacks, war and war-like actions, explosions, infrastructure failures or cyber attacks; •recorded loss reserves subsequently proving to have been inadequate; •the market value of White Mountains’s investment in MediaAlpha; •business opportunities (or lack thereof) that may be presented to it and pursued; •actions taken by rating agencies, such as financial strength or credit ratings downgrades or placing ratings on negative watch; •the continued availability of capital and financing; •the continued availability of fronting and reinsurance capacity; •deterioration of general economic, market or business conditions, including due to outbreaks of contagious disease and corresponding mitigation efforts; •competitive forces, including the conduct of other insurers; •changes in domestic or foreign laws or regulations, or their interpretation, applicable to White Mountains, its competitors or its customers; and •other factors, most of which are beyond White Mountains’s control. Consequently, all of the forward-looking statements made in this report are qualified by these cautionary statements, and there can be no assurance that the actual results or developments anticipated by White Mountains will be realized or, even if substantially realized, that they will have the expected consequences to, or effects on, White Mountains or its business or operations. White Mountains assumes no obligation to publicly update any such forward-looking statements, whether as a result of new information, future events or otherwise. 101