Risk Sleuth
WTM · 10-K filed 27 Feb 2026 · year to 31 Dec 2025

White Mountains Insurance Group

36 named things its latest annual report says its results depend on, each in the company's own words. 22 of them are also named by other companies we've read.

Read the filing on SEC.gov ↗

Customers

Build America Mutual Assurance Company (BAM)

earns fromnamed as a risk
HG Re is only licensed to provide reinsurance to BAM.Risk factors (Item 1A)

Fannie Mae and Freddie Mac

earns from
Ark underwrites a reinsurance portfolio supporting government-sponsored enterprises (Fannie Mae and Freddie Mac) and private mortgage insurers on both a proportional and excess of loss basis.Business (Item 1)

Also named by ELS, ICE, JOE, RF, SOFI, WY

Suppliers

Risk Management Solutions Inc.

depends on
Ark licenses third-party global property catastrophe models from Risk Management Solutions Inc. and Karen Clark & Company, as well as utilizes its own proprietary models to calculate expected probable maximum loss (“PML”) estimates from various property and non-property catastrophe scenarios.Business (Item 1)

Karen Clark & Company

depends on
Ark licenses third-party global property catastrophe models from Risk Management Solutions Inc. and Karen Clark & Company, as well as utilizes its own proprietary models to calculate expected probable maximum loss (“PML”) estimates from various property and non-property catastrophe scenarios.Business (Item 1)

Partners and platforms

Distinguished largest insurance carrier partner

depends on · approximately 22% of its businessnamed as a risk
Distinguished placed approximately 22% of its business with its single largest carrier during the year ended December 31, 2025.Risk factors (Item 1A)

Outrigger Re Ltd.

depends on · $70 million of capitalnamed as a risk
The inability to collect amounts due from reinsurers, including Outrigger Re Ltd., can result from a number of scenarios, including: (i) reinsurers withholding payment due to a dispute, including coverage terms, adverse judicial rulings or failed arbitration, or other factors beyond Ark’s control; (ii) reinsurers becoming unable to pay amounts owed to Ark as a result of a deterioration in their financial condition; and (iii) in the case of Outrigger Re Ltd., losses exceeding amounts within the collateral trust accounts.Risk factors (Item 1A)

Lloyd's of London

operates in · £850 million
Lloyd’s approved stamp capacity in 2026 for Syndicate 4020, including ACSN 3832, is £850 million ($1,148 million based upon the foreign currency exchange spot rate as of December 31, 2025) and for Syndicate 3902 is £250 million ($338 million based upon the foreign currency exchange spot rate as of December 31, 2025).Business (Item 1)

Also named by AJG, BRO, CB, CINF, CNA, HIG, L, MKL and 1 more

Marsh & McLennan Companies, Inc.

depends on · 24.3%
During the years ended December 31, 2025, 2024 and 2023, Ark received a significant portion of its gross written premiums from five insurance and reinsurance intermediaries.Business (Item 1)

Also named by BWIN

Aon plc

depends on · 12.4
During the years ended December 31, 2025, 2024 and 2023, Ark received a significant portion of its gross written premiums from five insurance and reinsurance intermediaries.Business (Item 1)

Also named by BWIN

Arthur J. Gallagher & Co

depends on · 15.2
During the years ended December 31, 2025, 2024 and 2023, Ark received a significant portion of its gross written premiums from five insurance and reinsurance intermediaries.Business (Item 1)

Howden Insurance Group

depends on · 8.7
During the years ended December 31, 2025, 2024 and 2023, Ark received a significant portion of its gross written premiums from five insurance and reinsurance intermediaries.Business (Item 1)

Willis Towers Watson plc

depends on · 4.1
During the years ended December 31, 2025, 2024 and 2023, Ark received a significant portion of its gross written premiums from five insurance and reinsurance intermediaries.Business (Item 1)

Other companies

BAM Surplus Notes

insures or lends to · principal balance of $277 million and accrued interest receivable of $214 millionnamed as a risk
As of December 31, 2025, White Mountains owned BAM Surplus Notes with a principal balance of $277 million and accrued interest receivable of $214 million, both at nominal value.Risk factors (Item 1A)

MediaAlpha

exposed to its price · $231 millionnamed as a risk
Should there be a significant decrease in the publicly-traded share price of MediaAlpha’s common stock, it could materially adversely affect our results of operations and financial condition.Risk factors (Item 1A)

A.M. Best

named as a risk
The maintenance of an “A-” or better financial strength rating is particularly important to Ark’s ability to write property and casualty insurance and reinsurance business in most markets.Risk factors (Item 1A)

Also named by CINF, CNA, KNSL, PGR, PRI, UHAL/B, WRB

Standard & Poor's

named as a risk
The maintenance of an “AA” or better financial strength rating from Standard & Poor’s is particularly important to BAM’s ability to conduct its business.Risk factors (Item 1A)

Also named by PLD, RLI

Competitors

Assured Guaranty Ltd.

competes withnamed as a risk
If BAM is unable to compete effectively against Assured, it could result in fewer policies issued, lower premium levels and less favorable policy terms and conditions, which could materially adversely affect HG Re’s business, and, consequently, could materially adversely affect our results of operations and financial condition.Risk factors (Item 1A)

Places

United Kingdom

operates in · $1,404.7
The following table shows Ark’s gross written premiums by geographic region based on the location of Ark’s underwriting offices for the years ended December 31, 2025, 2024 and 2023:Business (Item 1)

Also named by AGX, AJG, AMP, BAC, BF/B, BGC, BRO, C and 59 more

California

concentrated in · 17.9%
The following tables present the geographic distribution of HG Re’s insured portfolio as of December 31, 2025 and 2024:Business (Item 1)

Also named by A, AAON, AFRM, ALK, ALLY, AN, ARE, AVAV and 88 more

Texas

concentrated in · 16.5%
The following tables present the geographic distribution of HG Re’s insured portfolio as of December 31, 2025 and 2024:Business (Item 1)

Also named by ABR, AFRM, ALLY, AN, ASO, ASTS, ATO, AXP and 70 more

Pennsylvania

concentrated in · 8.4%
The following tables present the geographic distribution of HG Re’s insured portfolio as of December 31, 2025 and 2024:Business (Item 1)

Also named by AWK, CNX, DTM, EQT, FE, GMED, NFG, PEG and 6 more

Illinois

concentrated in · 9.3%
The following tables present the geographic distribution of HG Re’s insured portfolio as of December 31, 2025 and 2024:Business (Item 1)

Also named by AEE, ALL, AWK, CASY, CINF, DRVN, FPI, NNN and 4 more

Bermuda

operates in · $1,152.5
The following table shows Ark’s gross written premiums by geographic region based on the location of Ark’s underwriting offices for the years ended December 31, 2025, 2024 and 2023:Business (Item 1)

Also named by AJG, APO, KKR, PGR

Israel

operates innamed as a risk
For example, reductions of leisure travel, due to (i) travel restrictions imposed by governments due to the COVID-19 pandemic and (ii) fewer international flights in and out of Israel as a result of the regional conflict in the Middle East negatively impacted revenues at PassportCard/DavidShield.Risk factors (Item 1A)

Also named by AIOT, AKAM, AMAT, AMGN, APP, ASTS, AVY, BSX and 31 more

Hazards

U.S. earthquake

concentrated in · 20-35% of its tangible capitalnamed as a risk
Ark’s two largest natural catastrophe PML zones on a per occurrence basis for a 1-in-250 year event, as measured on a net after-tax exposure basis, are U.S. windstorm and U.S. earthquake.Business (Item 1)

Also named by A, ADBE, AEE, ARE, ARES, BLK, CDNA, CRC and 11 more

U.S. windstorm

concentrated in · 20-35% of its tangible capitalnamed as a risk
Ark’s two largest natural catastrophe PML zones on a per occurrence basis for a 1-in-250 year event, as measured on a net after-tax exposure basis, are U.S. windstorm and U.S. earthquake.Business (Item 1)

Also named by TNL

Japanese windstorm

concentrated in · less than 1% of White Mountains’s common equitynamed as a risk
WM Outrigger Re’s two largest remaining natural catastrophe PML zones on a per occurrence basis for a 1-in-250 year event as of January 2026, as measured net of reinstatement premiums, are U.S. earthquake and Japanese windstorm.Business (Item 1)

Commodities and inputs

Foreign currency exchange rates

exposed to its price · $376.4named as a risk
As of December 31, 2025, White Mountains had net assets of $376 million denominated in foreign currencies 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.Market risk (Item 7A)

Also named by ADP, AMT, CPAY, DPZ, DVA, GLW, HLIO, LNN and 1 more

Regulators

New York State Department of Financial Services (NYDFS)

subject tonamed as a risk
We cannot guarantee that the NYDFS will approve payments on the BAM Surplus Notes in the future.Risk factors (Item 1A)

Also named by AFL, AIG, AMP, BPOP, COIN, EFX, FNF, GS and 9 more

Financial Conduct Authority (FCA)

subject to
As an insurer in the United Kingdom, Ark is dual-regulated by the Financial Conduct Authority (the “FCA”) and the Prudential Regulation Authority (the “PRA”) (collectively, the “U.K. Regulators”).Business (Item 1)

Also named by AFRM, AJG, AMG, AMP, BGC, BRO, CBOE, COF and 17 more

Bermuda Monetary Authority (BMA)

subject to
The Insurance Act provides that no person may carry on any insurance business in or from within Bermuda unless registered as an insurer under the Insurance Act by the Bermuda Monetary Authority (“BMA”).Business (Item 1)

Also named by AFL, AIG, APO, ARES, CAT, CB, CG, COIN and 8 more

Prudential Regulation Authority (PRA)

subject to
As an insurer in the United Kingdom, Ark is dual-regulated by the Financial Conduct Authority (the “FCA”) and the Prudential Regulation Authority (the “PRA”) (collectively, the “U.K. Regulators”).Business (Item 1)

Also named by AIG, GS, TRV, UNM, WRB

Laws and programs

Bermuda corporate income tax

subject to · 15%named as a risk
The failure by White Mountains to meet the requirements of the five-year deferral under the Bermuda corporate income tax or the OECD Pillar Two UTPR could materially adversely affect our results of operations and financial condition.Risk factors (Item 1A)

Also named by KKR

OECD Pillar Two

subject tonamed as a risk
White Mountains expects to meet the requirements to be exempt from the U.K. UTPR until January 1, 2030.Risk factors (Item 1A)

Also named by APO, BAM, BAX, BF/B, CHRW, COHR, CPNG, CRM and 45 more

Municipal bond tax treatment

subject tonamed as a risk
Changes to such regulations or to the tax treatment of municipal bonds could affect the issuance of certain municipal bonds or could reduce the attractiveness of and market for BAM’s financial guarantee solutions.Risk factors (Item 1A)

Bermuda Insurance Act 1978

subject to
The Insurance Act 1978 of Bermuda and related regulations, as amended (the “Insurance Act”), regulates the insuranceBusiness (Item 1)