v3.26.3
Fair value measurements
 9 Months Ended
Sep. 30, 2026
Fair Value Disclosures [Abstract]  
Fair value measurements
6. Fair value measurements
U.S. GAAP disclosure requirements establish a framework for measuring fair value, including a three-level hierarchy for fair value measurements based upon the transparency of inputs to the valuation of an asset or liability. The three-level hierarchy of inputs is summarized below:
•Level 1 – Quoted prices available in active markets/exchanges for identical investments as of the reporting date.
•Level 2 – Observable inputs to the valuation methodology other than unadjusted quoted market prices for identical assets or liabilities in active markets. Level 2 inputs include, but are not limited to, prices quoted for similar assets or liabilities in active markets/exchanges, prices quoted for identical or similar assets or liabilities in markets that are not active and fair values determined through the use of models or other valuation methodologies.
•Level 3 – Inputs are based all or in part on significant unobservable inputs for the investment, and include situations where there is little, if any, market activity for the investment. The inputs applied in the determination of fair value require significant management judgment and estimation.
Inputs refer broadly to the assumptions that market participants would use in pricing the asset or liability, including, but not limited to, assumptions about risk inherent in a particular valuation technique used to measure fair value such as a pricing model and/or the risk inherent in the inputs to the valuation technique. Inputs may be observable or unobservable.
Observable inputs are inputs that reflect the assumptions market participants would use in pricing the asset or liability based on market data obtained from sources other than those of the reporting entity. Unobservable inputs are inputs that reflect the reporting entity’s own assumptions about the assumptions market participants would use in pricing the asset or liability developed based on the best information available in the circumstances.
In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, an investment’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement requires judgment and considers factors specific to the investment.
The following tables present the Company’s investments measured and reported at fair value, categorized by the level of the fair value hierarchy as of September 30, 2026 and December 31, 2025:
September 30, 2026
 Quoted prices in active markets Significant other observable inputs Significant unobservable inputs Total
 (Level 1) (Level 2) (Level 3)
Assets
Asset-backed securities$— $770.0 $— $770.0 
Residential mortgage-backed securities— 1,066.6 — 1,066.6 
Commercial mortgage-backed securities— 247.5 — 247.5 
Corporate debt securities— 2,380.1 — 2,380.1 
U.S. government and government agency880.8 — — 880.8 
Non-U.S. government and government agency— 19.8 — 19.8 
Total debt securities, available for sale880.8 4,484.0 — 5,364.8 
Asset-backed securities— 5.0 — 5.0 
Residential mortgage-backed securities— 24.9 — 24.9 
Commercial mortgage-backed securities— 19.5 — 19.5 
Corporate debt securities— 2.9 — 2.9 
U.S. government and government agency3.0 — — 3.0 
Total debt securities, trading3.0 52.3 — 55.3 
Short-term investments17.1 — — 17.1 
Other long-term investments— — 56.9 56.9 
Derivative assets— — 2.6 2.6 
$900.9 $4,536.3 $59.5 5,496.7 
Cost and equity method investments60.4 
Investments in funds valued at NAV159.2 
Total assets$5,716.3 
Liabilities
Derivative liabilities $— $— $24.6 $24.6 
Total liabilities$— $— $24.6 $24.6 
December 31, 2025
 Quoted prices in active markets Significant other observable inputs Significant unobservable inputs Total
 (Level 1) (Level 2) (Level 3)
Assets
Asset-backed securities$— $921.1 $— $921.1 
Residential mortgage-backed securities— 963.1 — 963.1 
Commercial mortgage-backed securities— 231.9 — 231.9 
Corporate debt securities— 2,198.2 — 2,198.2 
U.S. government and government agency835.7 — — 835.7 
Non-U.S. government and government agency— 18.6 — 18.6 
Total debt securities, available for sale835.7 4,332.9 — 5,168.6 
Asset-backed securities— 5.9 — 5.9 
Residential mortgage-backed securities— 45.0 — 45.0 
Commercial mortgage-backed securities— 31.9 — 31.9 
Corporate debt securities— 3.7 — 3.7 
U.S. Government and government agency3.8 — — 3.8 
Total debt securities, trading3.8 86.5 — 90.3 
Short-term investments28.3 — — 28.3 
Other long-term investments— 5.2 82.9 88.1 
Derivative assets— — 14.4 14.4 
$867.8 $4,424.6 $97.3 5,389.7 
Cost and equity method investments69.3 
Investments in funds valued at NAV157.7 
Total assets$5,616.7 
Liabilities
Derivative liabilities$— $— $9.0 $9.0 
Total liabilities$— $— $9.0 $9.0 
During the nine months ended September 30, 2026, the Company did not reclassify its assets or liabilities between Levels 2 and 3 (December 31, 2025 - no reclassifications).
Valuation techniques
The Company uses independent pricing services to assist in determining fair values for its investments. For investments in active markets, the Company uses the quoted market prices provided by independent pricing services to determine fair value. In circumstances where quoted market prices are unavailable or are not considered reasonable, the Company estimates the fair value using industry standard pricing models and observable inputs such as benchmark yields, reported trades, broker-dealer quotes, issuer spreads, benchmark securities, bids, offers, prepayment speeds, reference data including research publications, and other relevant inputs. Given that many debt securities do not trade on a daily basis, the independent pricing services evaluate a wide range of fixed maturity investments by regularly drawing parallels from recent trades and quotes of comparable securities with similar features. The characteristics used to identify comparable debt securities vary by asset type and take into account market convention.
The techniques and inputs specific to asset classes within the Company’s debt securities and short-term investments for Level 2 securities that use observable inputs are as follows:
Asset-backed and mortgage-backed securities
The fair value of mortgage and asset-backed securities is primarily priced by independent pricing services using a pricing model that uses information from market sources and leveraging similar securities. Key inputs include benchmark yields, reported trades, underlying tranche cash flow data, collateral performance, plus new issue data, as well as broker-dealer
quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers and reference data including issuer, vintage, loan type, collateral attributes, prepayment speeds, default rates, recovery rates, cash flow stress testing, credit quality ratings and market research publications.
Corporate debt securities
Corporate debt securities consist primarily of investment-grade debt of a wide variety of U.S. and non-U.S. corporate issuers and industries. The corporate fixed maturity investments are primarily priced by independent pricing services. When evaluating these securities, the independent pricing services gather information from market sources regarding the issuer of the security and obtain credit data, as well as other observations, from markets and sector news. Evaluations are updated by obtaining broker dealer quotes and other market information including actual trade volumes, when available. The independent pricing services also consider the specific terms and conditions of the securities, including any specific features which may influence risk.
U.S. government and government agency
U.S. government and government agency securities consist primarily of debt securities issued by the U.S. Treasury and mortgage pass-through agencies such as the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation and the Government National Mortgage Association. Fixed maturity investments included in U.S. government and government agency securities are primarily priced by independent pricing services. When evaluating these securities, the independent pricing services gather information from market sources and integrate other observations from markets and sector news. Evaluations are updated by obtaining broker dealer quotes and other market information including actual trade volumes, when available. The fair value of each security is individually computed using analytical models which incorporate option adjusted spreads and other daily interest rate data.
Non-U.S. government and government agency
Non-U.S. government and government agency securities consist of debt securities issued by non-U.S. governments and their agencies along with supranational organizations (also known as sovereign debt securities). Securities held in these sectors are primarily priced by independent pricing services who employ proprietary discounted cash flow models to value the securities. Key quantitative inputs for these models are daily observed benchmark curves for treasury, swap and high issuance credits. The independent pricing services then apply a credit spread for each security which is developed by in-depth and real time market analysis. For securities in which trade volume is low, the independent pricing services utilize data from more frequently traded securities with similar attributes. These models may also be supplemented by daily market and credit research for international markets.
U.S. states, municipalities, and political subdivisions
The U.S. states, municipalities and political subdivisions portfolio contains debt securities issued by U.S. domiciled state and municipal entities. These securities are generally priced by independent pricing services using the techniques for U.S. government and government agency securities described above.
Short-term investments
Short-term investments consist of U.S. treasury bills, certificates of deposit and other securities, which, at the time of purchase, mature within a period of greater than three months but less than one year. These investments are generally priced by independent pricing services using the techniques for U.S. government and government agency securities and Corporate debt securities described above.
Investments measured using Net Asset Value
The Company measures its investments in limited partnerships, including its investments in hedge funds and private equity funds, at fair value using the net asset value ("NAV") per share, or its equivalent, as a practical expedient. NAV represents the Company's proportionate interest in the partners' or members' equity of each fund, as reported by the fund's administrator or investment manager.

Since final fund valuations are generally not available as of the Company's reporting date, the Company records these investments on a lag of generally one to three months, using the most recent NAV or capital statement available. The reported NAV is adjusted for capital contributions and distributions during the lag period and for significant known events that
indicate a material change in value. Other changes in NAV are recognized in the period in which the capital statement is received.

These investments are included in investment in funds valued at NAV and excluded from the presentation of investments categorized by the level of the fair value hierarchy.
Level 3 Investments
Level 3 valuations are generated from techniques that use assumptions not observable in the market. These unobservable assumptions reflect the Company's assumptions that market participants would use in valuing the investment. Generally, certain securities may start out as Level 3 when they are originally issued but as observable inputs become available in the market, they may be reclassified to Level 2.
The Company employs a number of procedures to assess the reasonableness of the fair value measurements for its other long-term investments, including obtaining and reviewing the audited annual financial statements of hedge funds and private equity funds and periodically discussing each fund's pricing with the fund manager. However, since the fund managers do not provide sufficient information to evaluate the pricing inputs and methods for each underlying investment, the inputs are considered to be unobservable.
The fair values of the Company's investments in private equity securities, private debt instruments, certain private equity funds, and certain hedge funds have been classified as Level 3 measurements. Private equity securities and private debt instruments are initially valued based on transaction price and their valuation is subsequently estimated based on available evidence such as a market transaction in similar instruments and other financial information for the issuer.
For strategic investments carried at fair value, management either engages a third-party valuation specialist to assist in determination of the fair value based on commonly accepted valuation methods (e.g., income approach, market approach) as of the valuation date or performs valuation internally. In addition, investors’ fair value analyses prepared by third party valuation specialists working with strategic investment operating management are referenced where available. Where criteria to be accounted for under the equity method is not met, we have elected to value our strategic investments at the cost adjusted for market observable events less impairment method, a measurement alternative in which the investment is measured at cost and remeasured to fair value when determined to be impaired or upon observable transactions prices becoming available.
See Note 8 for additional information on the fair values of derivative financial instruments used for both risk management and investment purposes.
Underwriting-related derivatives
Underwriting-related derivatives include reinsurance contracts that are accounted for as derivatives. These derivative contracts are initially valued at cost which approximates fair value. In subsequent measurement periods, the fair values of these derivatives are determined using internally developed discounted cash flow models. As the significant inputs used to price these derivatives are unobservable, the fair values of these contracts are classified as Level 3.
The following tables present the reconciliation of investments measured at fair value using Level 3 inputs for the three and nine months ended September 30, 2026 and 2025:
July 1,
2026		Transfers in to (out of) Level 3PurchasesSales & Settlements
Realized and Unrealized Gains (Losses) (1)
September 30,
2026
Other long-term investments$57.5 $— $— $— $(0.6)$56.9 
Net derivatives (2)
$(22.9)$— $— $3.4 $(2.5)$(22.0)
January 1, 2026Transfers in to (out of) Level 3PurchasesSales & Settlements
Realized and Unrealized Gains(Losses) (1)
September 30,
2026
Other long-term investments$82.9 $— $— $(22.7)$(3.3)$56.9 
Net derivatives (2)
$5.4 $— $— $2.1 $(29.5)$(22.0)
July 1,
2025		Transfers in to (out of) Level 3PurchasesSales & Settlements
Realized and Unrealized Gains (Losses) (1)
September 30,
2025
Other long-term investments$87.0 $— $— $— $1.1 $88.1 
Net derivatives (2)
$6.8 $— $— $— $(6.8)$— 
January 1, 2025Transfers in to (out of) Level 3PurchasesSales & Settlements
Realized and Unrealized Gains (Losses) (1)
September 30,
2025
Other long-term investments$86.6 $— $— $— $1.5 $88.1 
Net derivatives (2)
$(13.4)$— $— $5.4 $8.0 $— 
(1)Total change in realized and unrealized gains (losses) recorded on Level 3 financial instruments is included in net investment gains (losses) in the consolidated statements of income. Realized and unrealized gains (losses) related to underwriting related derivative assets and liabilities are included in other revenues, net of foreign exchange (gains) losses, in the consolidated statements of income. See Note 8 “Derivatives” for classifications of gains (losses) on derivatives.
(2)Derivative assets are presented within Other assets on the consolidated balance sheets and derivative liabilities are presented within Other liabilities on the consolidated balance sheets. The amounts are presented net in the tables above for the purposes of the rollforward.
For assets and liabilities that were transferred into Level 3 during the period, gains (losses) are presented as if the assets or liabilities had been transferred into Level 3 at the beginning of the period; similarly, for assets and liabilities that were transferred out of Level 3 during the period, gains (losses) are presented as if the assets or liabilities had been transferred out of Level 3 at the beginning of the period.
The following table includes financial instruments for which the carrying value differs from the estimated fair values as of September 30, 2026 and December 31, 2025. The fair values of the below financial instruments are based on observable inputs and are considered Level 2 measurements.
September 30, 2026December 31, 2025
Fair ValueCarrying ValueFair ValueCarrying Value
2024 Senior Notes$406.8 $396.9 $424.2 $396.0 
2017 SEK Subordinated Notes276.0 270.6 293.3 292.6 
Series B preference shares (1)
$— $— $202.2 $200.0 
(1)The Series B preference shares were fully redeemed on February 26, 2026. See Note 14 for further discussion on the redemption.