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RESERVE FOR LOSSES AND LOSS EXPENSES
 12 Months Ended
Dec. 31, 2024
Insurance Loss Reserves [Abstract]  
RESERVE FOR LOSSES AND LOSS EXPENSES RESERVE FOR LOSSES AND LOSS EXPENSES
Reserving Methodology
Sources of Information
The Company's loss reserving process begins with the collection and analysis of paid and incurred claim data for each of the Company's segments. The segment data is disaggregated by line of business and further disaggregated by underwriting year and accident year. Underwriting year or accident year information is used to analyze the Company's business and to estimate reserves for losses and loss expenses. Lines of business are reviewed to ensure that the underlying contracts have homogeneous loss development characteristics, while remaining large enough to make the estimation of trends credible. The Company's lines of business are reviewed on a regular basis and adjusted over time as the Company's business evolves. The paid and incurred claim data serves as a key input to many of the methods employed by the Company's actuaries.
Actuarial Analysis
Multiple actuarial methods are available to estimate ultimate losses. Each method has its own assumptions and its own advantages and disadvantages, with no single estimation method being better than the others in all situations and no one set of assumption variables being meaningful for all lines of business. The relative strengths and weaknesses of the particular estimation methods when applied to a particular group of claims can also change over time.
The following is a brief description of the reserve estimation methods commonly employed by the Company's actuaries including a discussion of their particular strengths and weaknesses: 
•Expected Loss Ratio Method ("ELR Method"): This method estimates ultimate losses for an accident year or underwriting year by applying an expected loss ratio ("ELR") to the earned or written premium for that year. Generally, expected loss ratios are based on one or more of (a) an analysis of historical loss experience to date, (b) pricing information and (c) industry benchmark information, adjusted as appropriate, to reflect premium rate changes, loss and exposure trends, and terms and conditions. This method is insensitive to actual incurred losses for the accident year or underwriting year in question and is, therefore, often useful in the early stages of development when very few losses have been incurred. Conversely, the lack of sensitivity to incurred/paid losses for the accident year or underwriting year in question means that this method is usually inappropriate in later stages of an accident year or underwriting year’s development.
•Loss Development Method (also referred to as the "Chain Ladder Method" or "Link Ratio Method"): This method assumes that the losses incurred/paid for each accident year or underwriting year at a particular development stage follow a relatively similar pattern. It assumes that on average, every accident year or underwriting year will display the same percentage of ultimate losses incurred/paid at the same point in time after the inception of that year. The percentages incurred/paid are established for each development stage (e.g., 12 months, 24 months, etc.) after examining averages from historical loss development data and/or, in limited instances, industry benchmark information. Ultimate losses are then estimated by multiplying the actual incurred/paid losses by the reciprocal of the established incurred/paid percentage. The strengths of this method are that it reacts to loss emergence/payments and that it makes full use of historical claim emergence/payment experience. However, this method has weaknesses when the underlying assumption of stable loss development/payment patterns is not valid. This could be the consequence of changes in business mix, claim inflation trends or claim reporting practices and/or the presence of large claims, among other things. Furthermore, this method tends to produce volatile estimates of ultimate losses where there is volatility in the underlying incurred/paid patterns. In particular, where the expected percentage of incurred/paid losses is low, small deviations between actual and expected claims can lead to very volatile estimates of ultimate losses. As a result, this method is often unsuitable at early development stages for an accident year or underwriting year.
•Bornhuetter-Ferguson Method ("BF Method"): This method can be seen as a combination of the ELR and Loss Development Methods, under which the Loss Development Method is given progressively more weight as an accident year or underwriting year matures. The main advantage of the BF Method is that it provides a more stable estimate of ultimate losses than the Loss Development Method at earlier stages of development, while remaining more responsive to emerging loss development than the ELR Method. In addition, the BF Method allows for the incorporation of external market information through the use of expected loss ratios, whereas the Loss Development Method does not incorporate such information.
As part of the loss reserving process, the Company's actuaries employ the estimation method(s) that they believe will produce the most reliable estimate of ultimate losses, at that particular evaluation date, for each line of business and accident year or underwriting year combination. Often, this is a blend (i.e., weighted average) of the results of two or more appropriate actuarial methods.
These ultimate loss estimates are generally utilized to evaluate the adequacy of ultimate loss estimates for previous accident or underwriting years, established in the prior reporting period. For the initial estimate of the current accident or underwriting year, the available claim data is typically insufficient to produce a reliable estimate of ultimate losses. As a result, initial estimates for an accident or underwriting year are generally based on the ELR Method for longer tailed lines and a BF Method for shorter tailed lines.
The initial ELR for each line of business is established by the Company's actuaries at the start of the year as part of the planning process, taking into consideration prior accident years’ or underwriting years' experience and industry benchmark information, adjusted after considering factors such as loss and exposure trends, rate differences, changes in contract terms and conditions, business mix changes and other known differences between the current and prior accident or underwriting years. The initial expected loss ratios for a given accident or underwriting year may be modified over time if the underlying assumptions, such as loss development or premium rate changes, differ from the original assumptions.
Key Actuarial Assumptions
The use of the above actuarial methods requires the Company to make certain explicit assumptions, the most significant of which are expected loss ratios and loss development patterns and the Company relies on historical loss experience in establishing these assumptions. In establishing expected loss ratios for the insurance segment, consideration is given to a number of other factors, including exposure trends, rate adequacy on new and renewal business, ceded reinsurance costs, changes in claims emergence and the Company's underwriters’ view of terms and conditions in the market environment. For the reinsurance segment, expected loss ratios are based on a contract-by-contract review, which considers information provided by clients together with estimates provided by the Company's underwriters and actuaries about the impact of changes in pricing, terms and conditions and coverage. Market experience for some lines of business as compiled and analyzed by an independent actuarial firm is also considered, as appropriate.
Reserving for Catastrophic Events

The Company cannot estimate losses from widespread catastrophic events, such as hurricanes and earthquakes, using the traditional actuarial methods described above. The magnitude and complexity of losses associated with certain of these events inherently increase the level of uncertainty and, therefore, the level of management judgment involved in arriving at estimated net reserves for losses and loss expenses. As a result, actual losses for these events may ultimately differ materially from the Company's current estimates.
Net reserves for losses and loss expenses related to catastrophes represent the Company's best estimate of losses and loss expenses that have been incurred at December 31, 2024. The determination of these net reserves for losses and loss expenses is estimated by management after a catastrophe occurs by completing an in-depth analysis of individual contracts which may potentially have been impacted by the catastrophic event. This in-depth analysis may rely on several sources of information including:
•estimates of the size of insured industry losses from the catastrophic event and the Company's corresponding market share;
•a review of the Company's portfolio of contracts to identify those contracts which may be exposed to the catastrophic event;
•a review of the Company's claims notifications
•a review of modeled loss estimates based on information previously reported by customers and brokers, including exposure data obtained during the underwriting process;
•a review of the coverage provided by the Company's ceded reinsurance;
•discussions of the impact of the event with customers and brokers; and
•catastrophe bulletins published by various independent statistical reporting agencies.
A blend of these information sources is generally used to arrive at aggregate estimates of the ultimate losses arising from these catastrophic events.
While the Company believes its estimate of net reserves for losses and loss expenses is adequate for losses and loss expenses that have been incurred at December 31, 2024 based on current facts and circumstances, the Company monitors changes in paid and incurred losses in relation to each catastrophe in subsequent reporting periods and adjustments are made to estimates of ultimate losses for each event if there are developments that are different from previous expectations. Adjustments are recorded in the period in which they are identified. Actual losses for these events may ultimately differ materially from the Company's current estimates.
Selection of Reported Reserves – Management’s Best Estimate
The Company's loss reserving process involves the collaboration of its underwriting, claims, actuarial, ceded reinsurance and finance departments, including multiple committee meetings and culminates with the approval of a single point best estimate by the Company's Group Reserving Committee, which comprises senior management. In selecting this best estimate, management considers actuarial estimates and applies informed judgment regarding qualitative factors that may not be fully captured in these actuarial estimates. Such factors include, but are not limited to, the timing of the emergence of claims, volume and complexity of claims, social and judicial trends, potential severity of individual claims and the extent of Company historical loss data versus industry benchmark information. While these qualitative factors are considered in arriving at the point estimate, no specific provisions for qualitative factors are established.

Reserve for Losses and Loss Expenses

Reserve for losses and loss expenses comprise the following:
At December 31,20242023
Reserve for reported losses and loss expenses$5,433,903 $5,559,261 
Reserve for losses incurred but not reported11,785,026 10,874,757 
Reserve for losses and loss expenses$17,218,929 $16,434,018 
Reserve Roll-forward
The following table presents a reconciliation of the Company's beginning and ending gross reserves for losses and loss expenses and net reserves for unpaid losses and loss expenses:
Year ended December 31,202420232022
Gross reserve for losses and loss expenses, beginning of year$16,434,018 $15,168,863 $14,653,094 
Less reinsurance recoverable on unpaid losses and loss expenses, beginning of year(6,323,083)(5,831,172)(5,017,611)
Net reserve for unpaid losses and loss expenses, beginning of year10,110,935 9,337,691 9,635,483 
Net incurred losses and loss expenses related to:
Current year3,182,810 2,981,220 3,267,943 
Prior years(24,323)411,882 (25,533)
 3,158,487 3,393,102 3,242,410 
Net paid losses and loss expenses related to:
Current year(538,709)(488,016)(457,857)
Prior years(2,360,100)(2,185,588)(2,397,213)
 (2,898,809)(2,673,604)(2,855,070)
Foreign exchange and other7,419 53,746 (685,132)
Net reserve for unpaid losses and loss expenses, end of year10,378,032 10,110,935 9,337,691 
Reinsurance recoverable on unpaid losses and loss expenses, end of year6,840,897 6,323,083 5,831,172 
Gross reserve for losses and loss expenses, end of year$17,218,929 $16,434,018 $15,168,863 
The Company writes business with loss experience generally characterized as low frequency and high severity in nature, which can result in volatility in its financial results. During 2024, 2023 and 2022, the Company recognized catastrophe and weather-related losses, net of reinstatement premiums, of $226 million, $138 million and $403 million.
On September 22, 2023, the Company entered into a retrocession reinsurance agreement with a third-party reinsurer which was deemed to have met the established criteria for retroactive reinsurance accounting. At December 31, 2023, foreign exchange and other included an increase in reinsurance recoverable on unpaid losses of $74 million related to this transaction.
On December 9, 2022, the Company entered into loss portfolio transfer reinsurance agreements with a third-party reinsurer which were deemed to have met the established criteria for retroactive reinsurance accounting. At December 31, 2022, foreign exchange and other included an increase in reinsurance recoverable on unpaid losses of $422 million related to this transaction.
Estimates for Catastrophe Events
At December 31, 2024, net reserves for losses and loss expenses included estimated amounts for numerous catastrophe events. The magnitude and complexity of losses arising from certain of these events inherently increase the level of uncertainty and, therefore, the level of management judgment involved in arriving at estimated net reserves for losses and loss expenses. These events include Hurricane Milton and Hurricane Helene in 2024, Cyclone Gabrielle in 2023, Hurricane Ian, Winter Storm Elliot, June European Convective Storms, the Russia-Ukraine war and COVID-19 in 2022. As a result, actual losses for these events may ultimately differ materially from the Company's current estimates.
Prior Year Reserve Development
The Company's net favorable (adverse) prior year reserve development arises from changes to estimates for losses and loss expenses related to loss events that occurred in previous calendar years. The following table presents net favorable (adverse) prior year reserve development by segment:
Favorable (Adverse)
Insurance ReinsuranceTotal
Year ended December 31, 2024$16,209 $8,114 $24,323 
Year ended December 31, 2023$(176,353)$(235,529)$(411,882)
Year ended December 31, 2022$16,350 $9,183 $25,533 
The following sections provide further details on net favorable (adverse) prior year reserve development by segment, line of business and accident year.
Insurance Segment:
Favorable (Adverse)
Years ended December 31,202420232022
Property $17,718 $16,195 $52,512 
Accident and health4,191 (10,236)(12,856)
Marine and aviation(10,656)26,977 27,927 
Cyber— 35,579 8,416 
Professional lines— (41,243)(29,093)
Credit and political risk4,956 31,691 24,361 
Liability— (235,316)(54,917)
Total$16,209 $(176,353)$16,350 

In 2024, we recognized $16 million of net favorable prior year reserve development, the principal components of which were:

•$18 million of net favorable prior year reserve development on property business primarily due to better than expected loss emergence mainly related to the 2022 accident year.

•$5 million of net favorable prior year reserve development on credit and political risk business primarily due to better than expected loss emergence related to 2013 and older accident years and 2019 through 2022 accident years.

•$4 million of net favorable prior year development on accident and health business primarily due to better than expected loss emergence related to pet insurance business.
•$11 million of net adverse prior year reserve development on marine and aviation business primarily due to an increase in the loss estimate attributable to a specific large claim related to the 2019 accident year.

In 2023, we recognized $176 million of net adverse prior year reserve development, the principal components of which were:

•$235 million of net adverse prior year reserve development on liability business primarily due to reserve strengthening within the U.S. primary casualty book of business mainly related to 2022 and older accident years and U.S. programs books of business mainly related to 2017 through 2022 accident years. The reserve strengthening was attributable to updated trend assumptions, emerging development patterns and new industry data reflecting the impact of current economic and social inflation trends in the U.S. casualty market.

•$41 million of net adverse prior year reserve development on professional lines business primarily due to reserve strengthening within the U.S. financial institutions, U.S. commercial management solutions, U.S. design professional and environmental, and the international book of business related to 2019 and older accident years, and increases in loss estimates attributable to specific large claims within the international book of business related to 2012 and older accident years.

•$10 million of net adverse prior year development on accident and health business primarily due to reserve strengthening within the international book of business mainly related to the 2021 and 2022 accident years.

•$36 million of net favorable prior year reserve development on cyber business primarily due to better than expected loss emergence related to most accident years, partially offset by increases in loss estimates attributable to specific large claims related to the 2020 accident year.

•$32 million of net favorable prior year reserve development on credit and political risk business primarily due to a decrease in the loss estimate attributable to a specific large claim related to the 2020 accident year and better than expected loss emergence related to several accident years.

•$27 million of net favorable prior year reserve development on marine and aviation business primarily due to better than expected loss emergence attributable to the marine cargo and aviation books of business related to several accident years and better than expected loss emergence attributable to several catastrophe events.

•$16 million of net favorable prior year reserve development on property business primarily due to better than expected loss emergence mainly related to 2017 through 2019 accident years and better than expected loss emergence attributable to 2022 catastrophe events, partially offset by increases in loss estimates attributable to two specific large claims within the E&S book of business related to the 2016 and 2022 accident years.

In 2022, we recognized $16 million of net favorable prior year reserve development, the principal components of which were:

•$53 million of net favorable prior year reserve development on property business primarily due to better than expected loss emergence attributable to 2018 and 2020 catastrophe events and decreases in loss estimates attributable to specific large claims related to 2012 and older accident years.

•$28 million of net favorable prior year reserve development on marine and aviation business primarily due to better than expected loss emergence attributable to the marine cargo and specie, and marine offshore energy books of business mainly related to the 2018, 2019 and 2021 accident years, and better than expected loss emergence attributable to aviation business mainly related to the 2021 accident year.

•$24 million of net favorable prior year reserve development on credit and political risk business primarily due to better than expected loss emergence mainly related to 2017 through 2021 accident years.
•$8 million of net favorable prior year reserve development on cyber business primarily due to better than expected loss emergence mainly related to 2020 and older accident years, partially offset by reserve strengthening related to the 2021 accident year.

•$55 million of net adverse prior year reserve development on liability business primarily due to reserve strengthening within the U.S. programs book of business mainly related to 2016 through 2021 accident years, and the U.S. primary casualty book of business mainly related to 2015 through 2018 and the 2021 accident years.

•$29 million of net adverse prior year reserve development on professional lines business primarily due to reserve strengthening within the U.S. commercial management solutions book of business mainly related to the 2015, 2018 and 2019 accident years.

•$13 million of net adverse prior year development on accident and health business primarily due to reserve strengthening mainly related to 2019 through 2021 accident years.
Reinsurance Segment:
Favorable (Adverse)
Years ended December 31,202420232022
Accident and health$— $29,947 $14,199 
Agriculture— 10,781 11,703 
Marine and aviation4,111 12,595 2,597 
Professional lines— (92,181)(54,820)
Credit and surety4,003 8,306 43,567 
Motor— (9,653)18,161 
Liability— (262,114)(58,148)
Run-off lines
Catastrophe— 46,297 (504)
Property— 15,225 42,523 
Engineering— 5,268 (10,095)
Total run-off lines— 66,790 31,924 
Total$8,114 $(235,529)$9,183 
In 2024, we recognized $8 million of net favorable prior year reserve development, the principal components of which were:

•$4 million of net favorable prior year reserve development on marine and aviation business primarily due to better than expected loss emergence mainly related to the 2022 accident year.

•$4 million of net favorable prior year reserve development on credit and surety business primarily due to better than expected loss emergence attributable to the mortgage book of business mainly related to the 2020 accident year.
In 2023, we recognized $236 million of net adverse prior year reserve development, the principal components of which were:
•$262 million of net adverse prior year reserve development on liability business primarily due to reserve strengthening within the U.S. casualty and U.S. multiline/regional books of business related to all accident years. The reserve strengthening was attributable to updated trend assumptions, emerging development patterns and new industry data reflecting the impact of current economic and social inflation trends in the U.S. casualty market.
•$92 million of net adverse prior year reserve development on professional lines business primarily due to reserve strengthening within the U.S. proportional book of business mainly related to 2019 and older accident years, partially offset by better than expected loss emergence mainly related to the 2021 and 2022 accident years.

•$10 million of net adverse prior year reserve development on motor business primarily due to reserve strengthening to reflect increased estimates of future loss trend due to inflation and reserve strengthening attributable to the proportional book of business mainly related to 2018 through 2022 accident years.
•$30 million of net favorable prior year reserve development on accident and health business primarily due to better than expected loss emergence mainly related to 2018 through 2021 accident years.

•$13 million of net favorable prior year reserve development on marine and aviation business primarily due to better than expected loss emergence mainly related to the 2021 and 2022 accident years.
•$11 million of net favorable prior year reserve development on agriculture business primarily due to better than expected loss emergence mainly related to the 2022 accident year.

•$8 million of net favorable prior year reserve development on credit and surety business primarily due to better than expected loss emergence attributable to the international credit and mortgage books of business mainly related to the 2018 and 2019 accident years and the 2021 and 2022 accident years, partially offset by increases in loss estimates attributable to specific large claims related to the 2020 accident year.

Run-off lines

•$46 million of net favorable prior year reserve development on catastrophe business primarily due to better than expected loss emergence mainly attributable to 2022 events.

•$15 million of net favorable prior year reserve development on property business primarily due to better than expected loss emergence mainly attributable to 2022 catastrophe events.

•$5 million of net favorable prior year reserve development on engineering business primarily due to better than expected loss emergence mainly related to older accident years.

In 2022, we recognized $9 million of net favorable prior year reserve development, the principal components of which were:

•$44 million of net favorable prior year reserve development on credit and surety business primarily due to better than expected loss emergence mainly related to 2015 through 2021 accident years, most notably within the mortgage book of business related to the 2020 and 2021 accident years.

•$18 million of net favorable prior year reserve development on motor business primarily due to better than expected loss emergence mainly related to 2017 through 2020 accident years.

•$14 million of net favorable prior year reserve development on accident and health business primarily due to better than expected loss emergence mainly related to 2019 through 2021 accident years.

•$12 million of net favorable prior year reserve development on agriculture business primarily due to better than expected loss emergence mainly related to the 2019 and 2021 accident years.

•$58 million of net adverse prior year reserve development on liability business primarily due to increases in loss estimates attributable to specific large claims related to the 2018 and 2021 accident years and reserve strengthening within the U.S. non-proportional book of business related to 2016 through 2019 accident years.

•$55 million of net adverse prior year reserve development on professional lines business primarily due to increases in loss estimates attributable to one cedant related to several accident years, and reserve strengthening within the U.S. public D&O proportional book of business related to 2017 and older accident years.

Run-off lines

•$43 million of net favorable prior year reserve development on property business primarily due to better than expected loss emergence attributable to 2017 through 2021 catastrophe events and better than expected attritional loss emergence related to the 2021 accident year.

•$10 million of net adverse prior year reserve development on engineering business primarily due to increases in loss estimates attributable to specific large claims mainly related to the 2011, 2018 and 2019 accident years.
Net Incurred and Paid Claims Development Tables by Accident Year
The following tables present net incurred and paid claims development by accident year, total incurred-but-not-reported liabilities plus expected development on reported claims, cumulative reported claims frequency and average annual percentage payout of incurred claims by age for each line of business. The loss development tables are presented on an accident year basis for each line of business in the insurance and reinsurance segments. The Company does not discount reserves for losses and loss expenses.
Non-U.S. dollar denominated loss data is converted to U.S. dollar at the rates of exchange in effect at the balance sheet date for material underlying currencies. Fluctuations in foreign currency exchange rates may cause material shifts in loss development. Reserves for losses and loss expenses disclosed in the consolidated balance sheets are also remeasured using the rates of exchange in effect at the balance sheet date.
There are many considerations in establishing net reserves for losses and loss expenses. An attempt to evaluate net reserves for losses and loss expenses using solely the paid losses and claim counts presented in these tables could be misleading. When projecting net reserves for losses and loss expenses, the Company relies on several inputs in addition to the information presented in this disclosure including case incurred loss projections, changes in mix of business, external trends, and additional qualitative information. The Company cautions against mechanical application of standard actuarial methodologies to project ultimate losses using data presented in this disclosure.
Insurance Segment
The reporting of cumulative claims frequency for the lines of business within the insurance segment has been measured by counting the number of unique claim references including claim references assigned to nil and nominal case reserves. Claim references are grouped by claimant by loss event for each line of business. For certain insurance facilities and business produced by managing general agents where underlying data is reported to the Company in an aggregated format, the information necessary to provide cumulative claims frequency is not available therefore reporting of claims frequency is deemed to be impracticable.
Insurance Property
The property line of business provides physical loss or damage, business interruption and machinery breakdown cover for virtually all types of property, including commercial buildings, residential premises, construction projects, property in transit, onshore renewable energy installations, and physical damage and business interruption following an act of terrorism. This line of business includes primary and excess risks, some of which are catastrophe-exposed.
In general, reporting and payment patterns are relatively short although they can be volatile due to the incidence of catastrophe events.
Insurance property
Incurred claims and allocated claim adjustment expenses, net of reinsuranceAt December 31, 2024
For the years ended December 31,Total of incurred-but-not-reported liabilities plus expected development on reported claimsCumulative number of reported claims
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$207,189 $199,448 $191,577 $189,373 $186,032 $187,860 $177,908 $180,172 $180,785 $184,012 $1,053 4,199
2016261,565 284,462 276,891 262,436 256,514 256,766 256,192 261,379 260,698 (854)6,685
2017789,318 694,953 682,582 673,336 668,663 668,986 663,510 662,072 11,091 10,117
2018600,141 629,218 608,937 601,674 600,469 591,064 585,484 5,167 9,701
2019368,594 357,615 349,495 360,367 343,816 343,852 1,904 9,630
2020644,750 627,229 575,827 584,608 590,238 15,480 12,528
2021375,981 370,445 366,781 366,639 10,732 7,943
2022411,156 413,181 396,296 27,546 7,707
2023395,636 392,842 95,149 7,143
2024539,252 274,741 6,578
Total$4,321,385 
Insurance property
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance
For the years ended December 31,
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$67,399 $144,389 $165,268 $178,896 $178,566 $184,856 $176,079 $180,900 $180,576 $182,683 
201682,296 204,637 240,568 248,054 248,118 252,951 250,353 256,535 260,805 
2017190,148 509,202 616,838 644,936 639,939 629,525 641,640 642,182 
2018218,293 461,816 554,132 564,129 581,594 567,762 576,747 
2019145,556 251,877 298,564 335,077 323,935 328,429 
2020181,138 420,774 474,714 523,474 553,239 
2021133,671 284,332 319,737 338,393 
202296,815 259,261 323,805 
202390,343 206,885 
2024111,368 
Total3,524,536 
All outstanding liabilities before 2015, net of reinsurance13,825 
Liabilities for claims and claim adjustment expenses, net of reinsurance$810,674 
Insurance property
Average annual percentage payout of incurred claims by age, net of reinsurance (unaudited)
Year 1Year 2Year 3Year 4Year 5Year 6Year 7Year 8Year 9Year 10
31.2%40.2%13.2%5.7%0.6%0.5%(0.6%)1.7%0.7%1.1%
Insurance Accident and Health
The accident and health line of business includes personal accident, travel insurance and specialty health products for employer and affinity groups, and pet insurance.
In general, reporting and payment patterns are relatively short although they can be volatile due to the incidence of catastrophe events. An increase in limited benefits medical business written in 2017 resulted in a significant increase in reported claims observed in that year and subsequent years.
Insurance accident and health
Incurred claims and allocated claim adjustment expenses, net of reinsuranceAt December 31, 2024
For the years ended December 31,Total of incurred-but-not-reported liabilities plus expected development on reported claimsCumulative number of reported claims
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$70,003 $68,570 $65,066 $63,278 $63,844 $63,527 $62,860 $63,519 $60,850 $60,933 $1,075 44,138
201684,654 84,824 85,219 86,343 86,029 87,038 86,822 86,249 85,654 860 87,001
2017113,374 119,968 117,761 115,848 115,913 115,798 116,916 117,082 74 688,000
2018110,256 114,418 113,478 111,552 112,563 113,253 114,193 130 745,012
201973,130 74,067 64,562 68,028 67,110 69,578 556 675,633
202069,137 62,944 66,164 62,922 64,902 555 718,518
202168,873 70,639 76,918 75,036 1,664 440,175
202297,576 98,228 95,259 2,660 400,429
2023170,186 163,983 19,627 406,521
2024207,466 74,872 365,749
Total$1,054,086 
Insurance accident and health
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance
For the years ended December 31,
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$31,140 $56,263 $59,293 $60,154 $61,163 $61,032 $61,684 $61,775 $59,672 $59,820 
201641,127 78,239 82,003 82,836 83,897 84,288 84,989 84,125 84,869 
201762,733 108,219 113,393 114,788 115,890 115,070 116,933 117,122 
201861,218 105,324 107,655 111,312 112,202 113,014 114,104 
201944,652 60,623 62,033 66,971 66,828 68,263 
202036,035 51,481 59,608 57,944 61,786 
202138,828 60,470 68,183 69,489 
202245,663 80,164 87,242 
202393,765 135,134 
2024122,628 
Total920,457 
All outstanding liabilities before 2015, net of reinsurance
656 
Liabilities for claims and claim adjustment expenses, net of reinsurance$134,285 
Insurance accident and health
Average annual percentage payout of incurred claims by age, net of reinsurance (unaudited)
Year 1Year 2Year 3Year 4Year 5Year 6Year 7Year 8Year 9Year 10
54.2%33.2%6.0%1.9%1.7%0.5%1.1%(0.2%)(1.3%)0.2%
Insurance Marine and Aviation
The marine line of business provides cover for a range of exposures including offshore energy, renewable offshore energy, cargo, liability including kidnap and ransom, fine art, specie, and hull war. Offshore energy coverages include physical damage, business interruption, operator's extra expense and liability coverage for all aspects of offshore upstream energy from exploration and construction through the operation and distribution phases.

The complex nature of claims arising under marine policies tends to result in reporting and payment patterns that are longer than those of the property line of business with marine liability exhibiting the longest reporting and payment patterns as claims involve passengers and third parties. Exposure to natural perils such as windstorm and earthquake can result in volatility.
The aviation line of business provides cover for hull and liability, and specific war cover primarily for passenger airlines but also for cargo operations, general aviation operations, airports, aviation authorities, security firms and product manufacturers.
The claims reporting pattern varies by insurance coverage provided. Losses arising from war or terrorism and damage to hulls of aircraft are generally reported quickly compared with liability claims which involve passengers and third parties and generally exhibit longer reporting and payment patterns.
Insurance marine and aviation
Incurred claims and allocated claim adjustment expenses, net of reinsuranceAt December 31, 2024
For the years ended December 31,Total of incurred-but-not-reported liabilities plus expected development on reported claimsCumulative number of reported claims
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$186,023 $164,397 $159,304 $151,503 $138,907 $144,418 $143,385 $143,359 $141,862 $141,557 $1 4,316
2016115,442 111,630 109,092 101,322 100,703 99,830 100,732 101,680 100,809 2,930 4,898
2017260,225 227,207 224,246 222,060 213,940 213,545 212,002 211,499 5,926 8,589
2018234,768 251,517 237,372 230,422 223,605 225,057 225,769 11,695 8,787
2019213,917 208,026 210,690 223,032 221,512 246,540 4,556 7,755
2020207,122 178,537 161,953 163,264 167,229 9,134 6,533
2021238,454 219,002 201,232 222,356 20,126 6,922
2022263,742 254,138 255,744 68,596 7,650
2023297,529 261,711 99,643 7,266
2024341,298 185,817 6,103
Total$2,174,512 
Insurance marine and aviation
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance
For the years ended December 31,
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$29,464 $68,918 $123,818 $128,652 $131,418 $134,176 $140,256 $140,443 $140,449 $140,441 
201622,868 50,881 82,738 89,721 91,648 93,576 96,663 97,321 96,224 
201734,748 104,908 137,887 169,479 178,013 181,766 193,220 198,539 
201846,694 121,096 156,641 169,862 181,261 193,550 199,341 
201953,526 101,596 143,642 168,768 176,353 189,630 
202044,330 83,545 105,145 117,734 131,309 
202126,424 68,306 106,333 144,284 
202229,699 99,980 138,256 
202336,159 91,653 
202462,738 
Total1,392,415 
All outstanding liabilities before 2015, net of reinsurance13,787 
Liabilities for claims and claim adjustment expenses, net of reinsurance$795,884 
Insurance marine and aviation
Average annual percentage payout of incurred claims by age, net of reinsurance (unaudited)
Year 1Year 2Year 3Year 4Year 5Year 6Year 7Year 8Year 9Year 10
18.5%25.8%20.5%9.4%4.0%3.3%3.9%1.1%(0.6%)—%
Insurance Cyber

The cyber line of business provides cover for cyber, technology errors and omissions, media and miscellaneous professional liability. Cover is provided for a range of risks including data recovery and bricking, cyber-crime, liability and regulatory actions, business interruption, extortion, reputational harm, Payment Card Industry Data Security Standard and media liability.

Typically, this line of business takes longer to develop but specific first party coverages tend to develop more quickly than third party coverages.
Insurance cyber
Incurred claims and allocated claim adjustment expenses, net of reinsuranceAt December 31, 2024
For the years ended December 31,Total of incurred-but-not-reported liabilities plus expected development on reported claimsCumulative number of reported claims
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$65,231 $63,595 $63,066 $51,250 $50,357 $50,758 $52,526 $49,795 $48,042 $48,036 $2,226 1,428
201658,741 56,565 58,261 40,266 37,322 29,929 27,873 25,258 25,254 1,079 1,671
201753,187 50,794 56,783 51,931 50,910 48,696 48,343 46,036 (4)1,817
201833,429 31,966 33,962 30,558 26,168 23,902 29,447 1,845 2,156
201954,237 56,994 80,098 80,157 71,246 63,767 3,608 2,904
2020113,305 104,869 101,604 124,751 133,525 24,605 2,880
2021124,709 133,593 104,732 105,722 21,145 2,450
2022128,483 119,436 119,484 61,903 1,766
2023126,838 126,343 57,395 2,336
2024158,180 138,542 1,325
Total$855,794 
Insurance cyber
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance
For the years ended December 31,
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$5,572 $15,333 $25,544 $28,501 $30,865 $39,470 $42,515 $43,635 $45,432 $45,318 
20161,348 4,637 14,141 18,502 21,333 23,136 23,207 24,054 24,054 
20179,354 19,165 28,331 35,897 38,029 40,554 39,997 47,274 
20182,171 7,327 9,874 14,790 19,226 18,329 26,263 
20192,764 20,249 31,445 58,696 54,986 55,026 
202017,700 49,529 62,548 81,129 102,650 
202124,077 65,332 74,856 82,803 
20227,796 37,446 52,479 
20239,094 45,086 
202411,906 
Total492,859 
All outstanding liabilities before 2015, net of reinsurance
7,614 
Liabilities for claims and claim adjustment expenses, net of reinsurance$370,549 
Insurance cyber
Average annual percentage payout of incurred claims by age, net of reinsurance (unaudited)
Year 1Year 2Year 3Year 4Year 5Year 6Year 7Year 8Year 9Year 10
10.6%24.0%17.1%17.2%7.7%5.5%8.1%7.2%1.9%(0.2%)
Insurance Professional Lines
The professional lines line of business provides directors’ and officers’ liability, errors and omissions liability, employment practices liability, fiduciary liability, crime, professional indemnity, medical malpractice and other financial insurance related covers for public and private commercial enterprises, financial institutions, not-for-profit organizations and other professional service providers. This business is predominantly written on a claims-made basis.
Typically, this line of business is anticipated to exhibit longer reporting and payment patterns than most other insurance lines of business.
Insurance professional lines
Incurred claims and allocated claim adjustment expenses, net of reinsuranceAt December 31, 2024
For the years ended December 31,Total of incurred-but-not-reported liabilities plus expected development on reported claimsCumulative number of reported claims
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$308,206 $308,832 $315,378 $301,759 $288,635 $271,774 $270,615 $281,645 $280,054 $285,261 $12,111 9,662
2016287,119 291,739 295,992 314,273 326,544 336,376 337,725 354,094 359,445 21,448 10,949
2017336,606 339,010 371,856 372,365 388,467 386,243 390,818 395,866 37,337 12,966
2018323,638 339,960 388,834 419,568 445,299 464,430 467,834 32,176 15,537
2019345,193 360,720 375,361 408,326 455,966 466,546 74,818 14,793
2020320,300 318,886 299,016 290,925 292,430 92,856 9,634
2021375,982 366,527 323,579 320,376 157,986 8,656
2022457,637 443,592 437,668 297,452 8,740
2023438,129 440,324 335,563 10,252
2024488,514 459,342 7,556
Total$3,954,264 
Insurance professional lines
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance
For the years ended December 31,
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$14,128 $51,028 $110,043 $138,151 $169,386 $199,105 $211,577 $223,040 $247,794 $253,620 
201614,341 65,656 130,951 171,190 209,142 233,400 274,502 288,796 315,673 
201711,401 51,055 107,721 165,829 196,246 266,159 287,549 313,285 
201818,147 74,121 141,470 203,168 263,460 333,899 380,200 
201924,714 75,980 132,159 204,491 287,110 333,147 
20208,542 43,600 96,537 124,128 168,911 
20219,677 38,157 82,947 126,636 
202210,815 45,645 100,835 
202312,057 55,586 
202415,815 
Total2,063,708 
All outstanding liabilities before 2015, net of reinsurance143,974 
Liabilities for claims and claim adjustment expenses, net of reinsurance$2,034,530 
Insurance professional lines
Average annual percentage payout of incurred claims by age, net of reinsurance (unaudited)
Year 1Year 2Year 3Year 4Year 5Year 6Year 7Year 8Year 9Year 10
3.5%11.0%15.5%12.5%12.5%12.0%7.8%4.8%8.1%2.0%
Insurance Credit and Political Risk
The credit and political risk line of business provides credit and political risk insurance products for banks, commodity traders, corporations and multilateral and export credit agencies. Cover is provided for a range of risks including sovereign and corporate credit default, political violence, currency inconvertibility and non-transfer, expropriation, aircraft non-repossession and contract frustration due to political events. Surety bonds are also provided to large corporate and commercial clients and to mid to large sized construction clients.
The credit insurance coverage is primarily for lenders seeking to mitigate the risk of non-payment from their borrowers. In order to claim compensation under a credit insurance contract, the insured (most often a bank) cannot assign, without the Company's prior agreement, the insured contract (most often a loan) to any third-party and is normally obliged to hold a material portion of insured asset on their books, unhedged and uninsured. Claims for this business tend to be characterized by their severity risk, as opposed to their frequency risk.
Given the nature of the business, under the notification provisions of credit insurance policies issued by the Company, it anticipates being advised of an insured event within a relatively short time period. Consequently, the Company generally estimates ultimate losses based on a contract-by-contract analysis which considers the contracts’ terms, the facts and circumstances of underlying loss events and qualitative input from claims managers. Despite notification, credit and political risk claim reporting and payment patterns are anticipated to be volatile and can take longer to develop due to the complex nature of claims and the potential additional time that may be required to realize subrogation assets.

Insurance credit and political risk
Incurred claims and allocated claim adjustment expenses, net of reinsuranceAt December 31, 2024
For the years ended December 31,Total of incurred-but-not-reported liabilities plus expected development on reported claimsCumulative number of reported claims
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$30,329 $30,368 $27,524 $26,012 $25,930 $24,851 $24,189 $23,309 $23,309 $23,309 $— 2
201643,327 45,899 43,409 43,980 27,766 26,785 25,705 25,705 25,703 (2)2
201747,743 32,467 25,783 18,118 15,867 10,904 8,404 7,744 3,167 4
201842,339 33,166 32,057 24,093 20,464 23,774 24,379 5,084 2
201952,570 80,386 75,270 73,703 70,922 69,499 10,431 33
202060,857 69,650 60,212 49,018 47,927 18,124 44
202142,063 36,817 26,140 26,769 12,908 24
202245,035 44,078 43,030 34,088 27
202358,702 59,525 40,167 31
202471,968 67,838 20
Total$399,853 
Insurance credit and political risk
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance
For the years ended December 31,
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$— $23,309 $23,309 $23,309 $23,309 $23,309 $23,309 $23,309 $23,309 $23,309 
2016— 25,705 25,705 25,705 25,705 25,705 25,705 25,705 25,705 
2017397 3,985 9,138 11,573 10,786 10,237 8,514 5,940 
20185,327 13,300 15,299 11,376 19,486 23,362 22,928 
201915,859 46,227 53,489 56,682 54,747 53,948 
20209,416 88,017 55,084 50,349 50,018 
20212,769 (378)8,207 12,683 
20222,798 8,096 7,007 
20232,738 16,261 
20244,019 
Total221,818 
All outstanding liabilities before 2015, net of reinsurance5,977 
Liabilities for claims and claim adjustment expenses, net of reinsurance$184,012 
Insurance credit and political risk
Average annual percentage payout of incurred claims by age, net of reinsurance (unaudited)
Year 1Year 2Year 3Year 4Year 5Year 6Year 7Year 8Year 9Year 10
9.6%56.7%5.8%3.8%3.3%1.5%(6.0%)(11.1%)—%—%
Insurance Liability
The liability line of business primarily targets primary and low to mid-level excess and umbrella commercial liability, and environmental liability risks in the U.S. wholesale markets in addition to primary and excess of loss employers, public, and products liability business predominately in the U.K. Target industry sectors include construction, manufacturing, transportation and trucking and other services.
Typically, this line of business is anticipated to exhibit longer claim reporting and payment patterns than most other insurance lines of business and claims are often reported and ultimately paid or settled years, or even decades, after the related loss events occur.
Insurance liability
Incurred claims and allocated claim adjustment expenses, net of reinsuranceAt December 31, 2024
For the years ended December 31,Total of incurred-but-not-reported liabilities plus expected development on reported claimsCumulative number of reported claims
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$128,433 $127,087 $137,188 $164,685 $182,354 $187,650 $186,575 $187,816 $189,335 $194,101 $21,585 6,886
2016124,296 130,074 128,697 127,257 119,989 119,993 125,396 124,751 124,707 11,666 7,755
2017166,690 165,181 183,687 199,054 203,242 213,374 249,403 247,666 27,690 8,903
2018166,951 167,040 189,916 203,849 215,235 250,910 258,462 34,684 8,731
2019191,681 192,509 221,935 236,977 299,503 300,576 42,047 8,398
2020223,954 224,321 230,122 248,412 245,534 54,701 6,408
2021231,577 244,781 301,010 292,933 75,781 7,246
2022322,623 356,752 357,079 162,714 8,258
2023363,821 360,192 255,535 7,085
2024379,635 351,221 3,727
Total$2,760,885 
Insurance liability
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance
For the years ended December 31,
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$5,436 $22,200 $39,394 $92,350 $119,836 $140,484 $150,293 $158,595 $162,235 $166,225 
20166,299 23,211 36,317 56,319 66,157 79,396 95,615 102,588 106,095 
20175,354 29,185 58,560 114,856 142,497 167,554 189,184 201,124 
20189,252 34,843 72,057 118,847 158,255 188,416 200,368 
20197,787 39,694 83,412 138,666 191,870 223,818 
20208,129 25,094 75,733 118,034 155,974 
202113,384 51,736 103,537 166,205 
202213,191 53,365 124,788 
20239,829 54,318 
202412,241 
Total1,411,156 
All outstanding liabilities before 2015, net of reinsurance59,273 
Liabilities for claims and claim adjustment expenses, net of reinsurance$1,409,002 
Insurance liability
Average annual percentage payout of incurred claims by age, net of reinsurance (unaudited)
Year 1Year 2Year 3Year 4Year 5Year 6Year 7Year 8Year 9Year 10
3.4%10.7%14.8%20.2%13.6%10.7%7.9%4.9%2.4%2.1%
Reinsurance Segment
The presentation of net incurred and paid claims development tables by accident year for the reinsurance segment is challenging due to the need to allocate loss information related to proportional treaties to the appropriate accident years. Information related to proportional treaty reinsurance contracts is generally submitted to the Company via quarterly bordereaux reporting by underwriting year, with a supplemental listing of large losses. Large losses can be allocated to the corresponding accident years accurately. The remaining losses can generally only be allocated to accident years based on estimated premiums earned and loss reporting patterns. To the extent management’s assumptions and allocation procedures differ from the actual loss development patterns, the actual loss development may differ materially from the net incurred and paid claims development presented in the tables below.
The reporting of cumulative claims frequency for the lines of business within the reinsurance segment is deemed to be impracticable as the information necessary to provide cumulative claims frequency for these lines of business is not available to the Company.
Reinsurance Accident and Health
The accident and health line of business includes personal accident, specialty health, accidental death, travel, life and disability reinsurance products which are offered on a proportional and catastrophic or per life excess of loss basis.
In general, reporting and payment patterns are relatively short although they can be volatile due to the incidence of catastrophe events.
Reinsurance accident and health
Incurred claims and allocated claim adjustment expenses, net of reinsuranceDecember 31, 2024
For the years ended December 31,Total of incurred-but-not-reported liabilities plus expected development on reported claims
Accident Year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$93,754 $100,350 $93,862 $93,627 $92,906 $93,243 $92,251 $92,221 $92,966 $92,914 $84 
2016170,604 191,077 188,189 189,806 189,280 190,290 190,190 190,319 190,971 655 
2017183,761 189,292 183,173 182,013 183,023 182,973 181,916 182,326 384 
2018193,622 200,151 197,880 200,611 199,949 196,940 197,152 1,119 
2019217,364 211,873 207,308 204,907 198,928 199,155 1,108 
2020226,693 220,449 213,245 199,261 198,843 504 
2021231,917 226,777 222,084 218,106 3,442 
2022267,051 262,981 256,577 19,738 
2023242,835 251,034 43,093 
2024215,960 77,080 
Total$2,003,038 
Reinsurance accident and health
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance
For the years ended December 31,
Accident Year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$23,392 $77,212 $88,583 $91,789 $91,895 $92,362 $93,787 $93,599 $92,328 $92,314 
201650,017 149,814 180,891 187,052 189,036 188,632 189,558 189,146 189,131 
201779,215 156,941 171,794 178,569 179,075 179,725 179,491 179,715 
201872,826 164,972 191,414 190,959 194,064 194,539 194,680 
201967,755 169,294 195,595 196,317 194,411 199,235 
202081,783 171,822 210,093 191,899 192,168 
202168,549 179,195 209,615 212,355 
2022101,488 213,363 234,448 
2023130,720 199,466 
2024123,147 
Total1,816,659 
All outstanding liabilities before 2015, net of reinsurance
1,291 
Liabilities for claims and claim adjustment expenses, net of reinsurance$187,670 
Reinsurance accident and health
Average annual percentage payout of incurred claims by age, net of reinsurance (unaudited)
Year 1Year 2Year 3Year 4Year 5Year 6Year 7Year 8Year 9Year 10
38.7%46.4%13.1%0.4%0.4%0.7%0.5%(0.1%)(0.7%)—%
Reinsurance Agriculture
The agriculture line of business provides protection for risks associated with the production of food and fiber on a global basis for primary insurance companies writing multi-peril crop insurance, crop hail, and named peril covers, as well as custom risk transfer mechanisms for agricultural dependent industries with exposures to crop yield and/or price deviations. This business is written on a proportional and aggregate stop loss reinsurance basis.
In general, reporting and payment patterns are relatively short although they can be volatile due to the incidence of extreme weather events and in some territories take longer to settle due to government involvement in the loss adjustment process.
Reinsurance agriculture
Incurred claims and allocated claim adjustment expenses, net of reinsuranceDecember 31, 2024
For the years ended December 31,Total of incurred-but-not-reported liabilities plus expected development on reported claims
Accident Year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$103,144 $95,576 $95,321 $95,308 $95,314 $95,492 $95,476 $95,608 $96,225 $96,287 $(3)
2016123,359 117,045 110,207 108,795 109,042 108,219 108,167 108,912 108,701 14 
2017151,526 144,159 138,274 139,344 138,810 137,342 136,483 133,371 36 
2018140,830 147,182 140,727 140,457 139,823 142,610 146,050 399 
2019182,793 185,089 187,599 183,213 182,923 184,383 323 
202062,506 62,636 63,702 61,801 59,833 153 
202169,694 61,057 57,608 56,784 3,740 
2022101,001 91,299 90,378 3,573 
2023103,003 104,308 45,157 
202490,163 82,981 
Total$1,070,258 
Reinsurance agriculture
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance
For the years ended December 31,
Accident Year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$1,716 $65,845 $92,954 $94,511 $94,848 $95,442 $95,431 $95,586 $96,198 $96,237 
20169,489 61,772 107,559 109,092 108,564 108,324 108,364 108,915 108,609 
20177,444 124,429 137,338 138,468 137,308 137,255 136,431 133,133 
20185,115 127,449 135,514 141,607 138,233 143,905 144,073 
201928,854 154,426 174,094 178,098 177,587 179,673 
202017,454 47,254 54,101 55,182 55,589 
20212,952 32,715 45,895 48,518 
202215,344 55,371 75,383 
202314,591 47,580 
20243,654 
Total892,449 
All outstanding liabilities before 2015, net of reinsurance
162 
Liabilities for claims and claim adjustment expenses, net of reinsurance$177,971 
Reinsurance agriculture
Average annual percentage payout of incurred claims by age, net of reinsurance (unaudited)
Year 1Year 2Year 3Year 4Year 5Year 6Year 7Year 8Year 9Year 10
10.5%59.2%19.1%2.4%(0.5%)1.1%(0.1%)(0.6%)0.2%—%
Reinsurance Marine and Aviation
The marine line of business includes specialty marine exposures such as cargo, hull, pleasure craft, marine liability, inland marine and offshore energy. The principal perils covered by policies in this portfolio include physical loss, damage and/or liability arising from natural perils of the seas or land, man-made events including fire and explosion, stranding/sinking/salvage, pollution, shipowners and maritime employers liability. This business is written on a non-proportional and proportional basis.
The aviation line of business provides cover for airline, aerospace and general aviation exposures. This business is written on a proportional and non-proportional basis. The Company exited Aviation business effective January 1, 2023.
Losses arising from marine and aviation lines of business are generally reported quickly with the exception of marine and aviation liability claims which tend to exhibit longer reporting and payment patterns as claims involve passengers and third parties.
Reinsurance marine and aviation
Incurred claims and allocated claim adjustment expenses, net of reinsuranceDecember 31, 2024
For the years ended December 31,Total of incurred-but-not-reported liabilities plus expected development on reported claims
Accident Year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$10,360 $9,193 $10,777 $14,938 $12,589 $12,220 $11,986 $11,937 $11,993 $11,964 $441 
201632,111 34,714 35,092 36,486 34,982 35,309 35,715 35,208 35,920 131 
201754,853 42,541 40,935 46,176 42,787 40,443 40,366 41,445 78 
201818,797 27,331 26,877 43,264 46,729 48,103 47,392 1,198 
201969,487 81,921 79,650 81,494 84,590 86,262 4,059 
202040,006 41,273 37,298 36,464 37,990 1,803 
202143,366 40,438 35,108 38,786 1,642 
202268,401 58,762 49,649 17,062 
202340,526 37,916 20,892 
202448,826 41,877 
Total$436,150 
Reinsurance marine and aviation
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance
For the years ended December 31,
Accident Year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$416 $2,646 $6,417 $8,620 $10,177 $10,972 $10,798 $10,879 $11,012 $11,274 
20162,626 18,704 25,747 29,664 32,375 33,422 34,013 34,223 34,605 
20172,674 23,370 28,664 33,578 36,600 36,708 37,610 39,064 
20181,776 10,815 24,223 30,639 34,252 37,601 39,599 
201910,672 27,031 34,246 52,675 67,673 72,288 
20203,983 16,455 23,525 29,316 32,332 
20215,407 12,160 20,118 27,671 
20227,732 18,402 24,732 
20231,472 6,902 
20242,045 
Total290,512 
All outstanding liabilities before 2015, net of reinsurance
3,706 
Liabilities for claims and claim adjustment expenses, net of reinsurance$149,344 
Reinsurance marine and aviation
Average annual percentage payout of incurred claims by age, net of reinsurance (unaudited)
Year 1Year 2Year 3Year 4Year 5Year 6Year 7Year 8Year 9Year 10
8.2%26.4%19.1%15.8%10.1%4.4%1.6%1.6%1.1%2.2%
Reinsurance Professional Lines
The professional lines line of business provides protection for directors' and officers' liability, employment practices liability, medical malpractice, professional indemnity, cyber, and miscellaneous errors and omissions insurance risks. The underlying business is predominantly written on a claims-made basis. This business is written on a proportional and excess of loss basis.
Typically, this line of business is anticipated to exhibit longer claim reporting and payment patterns than most other reinsurance lines of business.
Reinsurance professional lines
Incurred claims and allocated claim adjustment expenses, net of reinsuranceAt December 31, 2024
For the years ended December 31,Total of incurred-but-not-reported liabilities plus expected development on reported claims
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$211,361 $211,024 $213,232 $223,865 $230,444 $227,420 $233,925 $239,843 $250,896 $250,292 $15,211 
2016194,564 195,543 198,934 226,305 253,676 253,578 265,439 277,105 276,527 18,210 
2017154,215 154,560 160,679 176,245 185,849 208,425 237,237 237,500 27,326 
2018144,599 146,713 153,514 164,134 172,179 193,077 190,588 (677)
2019135,866 135,003 138,634 143,617 154,826 149,984 15,699 
2020138,881 138,846 133,815 131,679 135,632 55,500 
2021147,464 139,462 134,870 135,793 77,868 
2022168,535 152,352 152,014 99,800 
2023135,093 135,427 106,522 
2024106,558 96,010 
Total$1,770,315 
Reinsurance professional lines
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance
For the years ended December 31,
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$3,134 $13,502 $41,440 $79,127 $111,504 $131,185 $151,960 $169,894 $183,371 $199,230 
20161,752 20,397 52,347 94,682 124,288 152,878 180,296 201,985 222,284 
20172,812 14,746 39,723 62,483 88,279 115,586 136,560 165,728 
2018273 2,495 30,964 56,426 81,129 112,549 137,940 
2019362 13,463 33,104 52,368 74,942 97,450 
20203,820 13,773 26,460 40,009 57,776 
20214,337 11,320 22,453 38,523 
20223,233 11,684 28,924 
20233,452 12,388 
20242,962 
Total963,205 
All outstanding liabilities before 2015, net of reinsurance136,065 
Liabilities for claims and claim adjustment expenses, net of reinsurance$943,175 
Reinsurance professional lines
Average annual percentage payout of incurred claims by age, net of reinsurance (unaudited)
Year 1Year 2Year 3Year 4Year 5Year 6Year 7Year 8Year 9Year 10
1.7%5.6%11.3%12.6%12.6%12.2%10.1%9.1%6.4%6.3%
Reinsurance Credit and Surety
The credit and surety line of business which provides protection for trade credit insurance and credit and political risk insurance. Trade credit insurance protects sellers of goods and services in the event of a non-payment by the buyer of those goods and services. Credit and political risk insurance covers a range of risks predominantly corporate and sovereign non-payment. Surety reinsurance provides protection for losses arising from a broad array of surety bonds issued by insurers to satisfy regulatory demands, contract, and commercial obligations in a variety of jurisdictions around the world. Mortgage reinsurance is provided to mortgage guaranty insurers, U.S. government-sponsored entities and other mortgage participants. These entities seek to manage their credit risk exposure emanating from defined pools of mortgage loans.
Initial and most recent underwriting year loss projections are generally based on the ELR Method, with consideration given to qualitative factors. Given that there is a quicker and more stable reporting pattern for trade credit and mortgage business, the Company generally commences the transition to experience-based methods sooner for these lines of business than for surety business.
Reinsurance credit and surety
Incurred claims and allocated claim adjustment expenses, net of reinsuranceAt December 31, 2024
For the years ended December 31,Total of incurred-but-not-reported liabilities plus expected development on reported claims
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$156,256 $159,662 $154,425 $150,883 $132,750 $133,679 $134,817 $129,441 $125,761 $125,755 $1,361 
2016138,199 136,760 144,405 119,427 112,113 109,778 107,428 109,579 111,169 592 
2017135,014 128,141 122,255 113,551 111,099 110,948 111,360 110,277 2,239 
2018108,874 115,673 109,266 106,339 101,044 87,774 87,535 3,276 
201972,245 64,952 64,711 62,649 54,467 54,501 3,369 
202076,156 82,568 68,240 94,044 89,395 13,239 
202151,523 43,356 40,832 41,061 13,639 
202263,310 50,474 50,203 30,771 
202385,730 85,451 45,993 
202479,933 54,383 
Total$835,280 
Reinsurance credit and surety
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance
For the years ended December 31,
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$32,721 $78,814 $95,640 $111,972 $113,904 $117,515 $118,370 $117,224 $114,711 $115,099 
201641,639 70,896 88,974 98,411 99,415 97,926 97,638 99,762 99,527 
201737,018 71,362 87,088 98,480 96,569 99,473 100,308 100,954 
201838,619 65,916 69,263 80,736 82,379 83,859 84,092 
201919,163 29,432 42,248 44,277 46,442 46,199 
202025,277 33,572 38,972 43,304 48,666 
20214,460 8,909 16,768 18,726 
20226,845 10,916 13,259 
202310,314 20,167 
202411,398 
Total558,087 
All outstanding liabilities before 2015, net of reinsurance28,849 
Liabilities for claims and claim adjustment expenses, net of reinsurance$306,042 
Reinsurance credit and surety
Average annual percentage payout of incurred claims by age, net of reinsurance (unaudited)
Year 1Year 2Year 3Year 4Year 5Year 6Year 7Year 8Year 9Year 10
25.6%20.4%12.6%8.3%2.1%1.1%0.4%0.5%(1.1%)0.3%
Reinsurance Motor
The motor line of business provides protection to insurers for motor liability and motor property damage losses arising out of any one occurrence. A loss occurrence can involve one or many claimants where the ceding insurer aggregates the claims from the occurrence. The Company offers traditional non-proportional and proportional reinsurance as well as structured solutions predominantly relating to European exposures.
The motor non-proportional business consists of standard excess of loss contracts written for cedants in several European countries with most of the premium related to two major markets, U.K. and France. Since 2009/2010, an increasing number of large bodily injury settlements in the U.K. market were settled using indexed annuities (Periodical Payment Orders "PPOs"). This led to a materially longer development tail on the older accident years for the U.K. non-proportional motor book. This also resulted in the inclusion of capitalization clauses on a number of U.K. motor treaties which allow reinsurers to settle claims arising under PPOs with a lump sum payment, to help mitigate the lengthening of the development tail on more recent accident years.
In 2017, the U.K. Ministry of Justice announced a decrease in the discount rate to be used to calculate lump sum awards in U.K. bodily injury cases, known as the Ogden Rate. Effective March 20, 2017, the Ogden rate changed from plus 2.5% to minus 0.75%. This resulted in a trend toward a lower number of claims settlements using PPOs and an increase in projected ultimate losses, particularly related to recent accident years.
Effective August 5, 2019, the Ogden rate changed from minus 0.75% to minus 0.25%. This resulted in a decrease in projected ultimate losses, particularly related to recent accident years.
The motor proportional business generally has a shorter reported and payment pattern, relative to the motor non-proportional business.
Reinsurance motor
Incurred claims and allocated claim adjustment expenses, net of reinsuranceAt December 31, 2024
For the years ended December 31,Total of incurred-but-not-reported liabilities plus expected development on reported claims
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$215,985 $208,783 $212,699 $214,510 $204,009 $203,169 $200,453 $200,843 $199,519 $199,471 $10,658 
2016239,098 252,847 254,013 244,592 236,810 234,357 238,113 238,717 238,942 1,903 
2017353,883 358,716 347,805 348,494 349,584 344,966 351,598 351,699 21,818 
2018348,090 343,752 354,625 351,594 339,260 351,737 350,894 17,085 
2019331,840 330,204 330,904 321,798 326,641 326,155 7,574 
2020209,930 212,344 208,823 192,333 192,990 7,877 
2021176,116 176,135 178,461 178,561 22,550 
2022154,073 166,810 158,097 24,177 
2023121,411 128,732 23,925 
202484,425 50,610 
Total$2,209,966 
Reinsurance motor
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance
For the years ended December 31,
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$57,035 $90,219 $109,330 $126,014 $141,391 $141,761 $164,226 $169,228 $171,272 $175,513 
201660,117 101,425 124,192 141,526 153,840 177,453 184,773 193,160 202,406 
201771,292 130,330 159,573 193,899 215,552 238,380 256,263 266,624 
201883,155 138,377 201,610 210,849 234,853 254,645 273,683 
201989,950 182,006 198,344 219,950 238,617 257,423 
202043,468 94,350 113,316 125,200 134,082 
202141,657 74,997 92,381 104,602 
202235,075 51,509 63,668 
202325,966 44,970 
202415,114 
Total1,538,085 
All outstanding liabilities before 2015, net of reinsurance262,566 
Liabilities for claims and claim adjustment expenses, net of reinsurance$934,447 
Reinsurance motor
Average annual percentage payout of incurred claims by age, net of reinsurance (unaudited)
Year 1Year 2Year 3Year 4Year 5Year 6Year 7Year 8Year 9Year 10
23.2%18.3%9.7%6.8%6.0%5.6%6.2%3.0%2.5%2.1%
Reinsurance Liability
The liability line of business provides protection to insurers of admitted casualty business, excess and surplus lines casualty business and specialty casualty programs. The primary focus of the underlying business is general liability, workers' compensation, auto liability, environmental liability, and excess casualty.
Typically, this line of business is anticipated to exhibit longer claim reporting and payment patterns than most other reinsurance lines of business and claims are often reported and ultimately paid or settled years, or even decades, after the related loss events occur.
Reinsurance liability
Incurred claims and allocated claim adjustment expenses, net of reinsuranceAt December 31, 2024
For the years ended December 31,Total of incurred-but-not-reported liabilities plus expected development on reported claims
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$213,111 $213,356 $214,303 $214,193 $212,052 $212,453 $202,266 $205,170 $215,869 $215,609 $12,588 
2016238,237 243,345 248,154 251,425 260,727 264,490 271,912 311,876 313,766 30,063 
2017273,121 267,788 276,627 285,245 294,535 303,916 339,798 338,776 25,655 
2018262,170 266,567 271,505 284,659 304,407 349,520 349,317 47,871 
2019262,105 270,541 272,501 271,351 329,313 334,773 82,959 
2020282,298 282,700 277,534 303,976 307,787 104,900 
2021302,849 310,334 343,399 334,588 139,743 
2022346,756 341,727 334,639 165,420 
2023273,950 273,571 170,489 
2024247,866 217,212 
Total$3,050,692 
Reinsurance liability
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance
For the years ended December 31,
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$7,266 $27,432 $54,372 $80,691 $108,548 $130,417 $141,135 $151,506 $166,279 $178,276 
201611,837 37,527 69,136 111,165 142,074 165,531 188,319 215,185 234,297 
201712,394 41,984 78,240 120,145 157,920 192,427 223,321 250,245 
201819,352 49,673 84,839 127,457 165,827 206,294 244,159 
201919,288 45,132 79,439 119,854 158,542 201,377 
202016,930 48,916 82,113 119,248 152,616 
202110,882 58,253 98,671 145,566 
202218,024 51,960 102,346 
202314,979 45,121 
202413,368 
Total1,567,371 
All outstanding liabilities before 2015, net of reinsurance127,910 
Liabilities for claims and claim adjustment expenses, net of reinsurance$1,611,231 
Reinsurance liability
Average annual percentage payout of incurred claims by age, net of reinsurance (unaudited)
Year 1Year 2Year 3Year 4Year 5Year 6Year 7Year 8Year 9Year 10
4.7%9.8%11.5%12.6%11.2%10.4%8.1%7.1%6.5%5.6%
Reinsurance Run-off lines
Run-off lines include catastrophe, property, and engineering lines of business.
The catastrophe line of business provides protection for most catastrophic losses that are covered in the underlying insurance policies written by the Company's cedants. The underlying policies principally cover property-related exposures but other exposures including worker's compensation and personal accident are also covered. The principal perils covered by policies in this portfolio include hurricane and windstorm, earthquake, flood, tornado, hail and fire. In some instances, terrorism may be a covered peril or the only peril. This business is written on a proportional and an excess of loss basis. The Company exited this line of business in June 2022.
The property line of business provides protection for property damage and related losses resulting from natural and man-made perils that are covered in underlying personal and commercial lines insurance policies written by the Company's cedants. The predominant exposure is to property damage, but other risks, including business interruption and other non-property losses, may also be covered when arising from a covered peril. The most significant perils covered by policies in this portfolio include windstorm, tornado and earthquake, but other perils such as freezes, riots, flood, industrial explosions, fire, hail and a number of other loss events are also included. This business is written on a proportional and excess of loss basis. The Company exited this line of business in June 2022.
The engineering line of business provides protection for all types of construction risks and risks associated with erection, testing and commissioning of machinery and plants during the construction stage. This line of business also includes cover for losses arising from operational failures of machinery, plant and equipment, and electronic equipment as well as business interruption. The Company exited this line of business in 2020.

In general, reporting and payment patterns are relatively short although they can be volatile due to the incidence of catastrophe events. Losses from engineering exposures tend to develop slower than the other reinsurance run-off lines of business.
Reinsurance run-off
Incurred claims and allocated claim adjustment expenses, net of reinsuranceAt December 31, 2024
For the years ended December 31,Total of incurred-but-not-reported liabilities plus expected development on reported claims
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$264,343 $252,265 $252,266 $243,094 $241,916 $246,713 $244,566 $242,674 $240,289 $240,152 $1,636 
2016278,963 277,871 275,202 269,952 273,294 273,472 273,184 266,307 265,991 3,048 
2017701,995 702,732 743,852 744,427 742,270 733,045 725,458 729,636 23,633 
2018518,635 603,305 617,932 603,972 589,801 589,927 587,086 14,977 
2019431,902 407,538 387,635 372,883 366,152 368,869 14,143 
2020509,942 538,067 533,206 537,210 533,431 31,778 
2021419,674 427,037 422,974 421,678 28,832 
2022260,346 218,849 221,806 43,059 
202363,904 60,979 21,860 
202428,826 7,873 
Total$3,458,454 
Reinsurance run-off
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance
For the years ended December 31,
Accident year2015 unaudited2016 unaudited2017 unaudited2018 unaudited2019 unaudited2020 unaudited2021 unaudited2022 unaudited2023 unaudited2024
2015$46,281 $117,515 $175,420 $200,069 $210,135 $214,446 $228,479 $230,094 $231,029 $232,580 
201663,381 137,032 195,162 225,752 239,689 246,337 251,662 250,127 252,695 
2017163,739 419,762 533,804 591,946 615,721 650,897 661,617 672,949 
2018116,822 326,092 419,373 471,002 517,408 538,362 546,510 
201955,275 199,958 256,712 291,464 315,548 329,517 
2020104,927 234,874 316,569 383,462 429,759 
202187,733 230,145 292,521 341,460 
202249,727 101,413 133,777 
202322,862 29,381 
202411,372 
Total2,980,000 
All outstanding liabilities before 2015, net of reinsurance38,605 
Liabilities for claims and claim adjustment expenses, net of reinsurance$517,059 
Reinsurance run-off
Average annual percentage payout of incurred claims by age, net of reinsurance (unaudited)
Year 1Year 2Year 3Year 4Year 5Year 6Year 7Year 8Year 9Year 10
24.0%28.8%17.2%10.3%6.0%3.3%2.7%0.6%0.7%0.6%
Reconciliation of Loss Development Tables to Consolidated Balance Sheet
The following table reconciles the reserve for losses and loss expenses at December 31, 2024, included in the loss development tables to the reserve for losses and loss expenses reported in the consolidated balance sheet:
Reconciliation of the disclosure of incurred and paid claims development to the liability
for unpaid claims and claim adjustment expenses
At December 31, 2024
Net outstanding liabilitiesReinsurance recoverable on unpaid claimsGross outstanding liabilities
Insurance segment
Property$810,674 $476,362 $1,287,036 
Accident and health134,285 9,565 143,850 
Marine and aviation795,884 348,062 1,143,946 
Cyber370,549 455,301 825,850 
Professional lines2,034,530 1,365,043 3,399,573 
Credit and political risk184,012 35,302 219,314 
Liability1,409,002 2,106,520 3,515,522 
Total insurance segment5,738,936 4,796,155 10,535,091 
Reinsurance segment
Accident and health187,670 61,724 249,394 
Agriculture177,971 10,917 188,888 
Marine and aviation149,344 26,273 175,617 
Professional lines943,175 440,572 1,383,747 
Credit and surety306,042 132,474 438,516 
Motor934,447 352,438 1,286,885 
Liability1,611,231 813,796 2,425,027 
Run-off lines517,059 206,548 723,607 
Total reinsurance segment4,826,939 2,044,742 6,871,681 
Total$10,565,875 $6,840,897 17,406,772 
Unallocated claims adjustment expenses212,623 
Foreign exchange and other(1)
(10,992)
Ceded reserves related to retroactive transactions (389,474)
Total liability for unpaid claims and claims adjustment expense$17,218,929 
(1)    Non-U.S. dollar denominated loss data is converted to U.S dollar at the rates of exchange in effect at the balance sheet date for material underlying currencies. Fluctuations in currency exchange rates may cause material shifts in loss development. Reserves for losses and loss expenses disclosed in the consolidated balance sheets are also remeasured using rates of exchange in effect at the balance sheet date.