The Company's reserves for losses and loss expenses are comprised of case reserves and incurred but not reported liabilities ("IBNR"). When a claim is reported, a case reserve is established for the estimated ultimate payment based upon known information about the claim. As more information about the claim becomes available over time, case reserves are adjusted up or down as appropriate. Reserves are also established on an aggregate basis to provide for IBNR liabilities and expected loss reserve development on reported claims.

Loss reserves included in the Company’s financial statements represent management’s best estimates based upon an actuarially derived point estimate and other considerations. The Company uses a variety of actuarial techniques and methods to derive an actuarial point estimate for each operating unit. These methods include paid loss development, incurred loss development, paid and incurred Bornhuetter-Ferguson methods and frequency and severity methods. In circumstances where one actuarial method is considered more credible than the others, that method is used to set the point estimate. The actuarial point estimate may also be based on a judgmental weighting of estimates produced from each of the methods considered. Industry loss experience is used to supplement the Company’s own data in selecting “tail factors” in areas where the Company’s own data is limited. The actuarial data is analyzed by line of business, coverage and accident or policy year, as appropriate, for each operating unit.

The establishment of the actuarially derived loss reserve point estimate also includes consideration of qualitative factors that may affect the ultimate losses. These qualitative considerations include, among others, the impact of re-underwriting initiatives, changes in the mix of business, changes in distribution sources and changes in policy terms and conditions.

The key assumptions used to arrive at the best estimate of loss reserves are the expected loss ratios, rate of loss cost inflation, and reported and paid loss emergence patterns. Expected loss ratios represent management’s expectation of losses at the time the business is priced and written, before any actual claims experience has emerged. This expectation is a significant determinant of the estimate of loss reserves for recently written business where there is little paid or incurred loss data to consider. Expected loss ratios are generally derived from historical loss ratios adjusted for the impact of rate changes, loss cost trends and known changes in the type of risks underwritten. Expected loss ratios are estimated for each key line of business within each operating unit. Expected loss cost inflation is particularly important for the long-tail lines, such as excess casualty, and claims with a high medical component, such as workers’ compensation. Reported and paid loss emergence patterns are used to project current reported or paid loss amounts to their ultimate settlement value. Loss development factors are based on the historical emergence patterns of paid and incurred losses, and are derived from the Company’s own experience and industry data. The paid loss emergence pattern is also significant to excess and assumed workers’ compensation reserves because those reserves are discounted to their estimated present value based upon such estimated payout patterns.

Loss frequency and severity are measures of loss activity that are considered in determining the key assumptions described in our discussion of loss and loss expense reserves, including expected loss ratios, rate of loss cost inflation and reported and paid loss emergence patterns. Loss frequency is a measure of the number of claims per unit of insured exposure, and loss severity is a measure of the average size of claims. Factors affecting loss frequency include the effectiveness of loss controls and safety programs and changes in economic activity or weather patterns. Factors affecting loss severity include changes in policy limits, retentions, rate of inflation and judicial interpretations.

Another factor affecting estimates of loss frequency and severity is the loss reporting lag, which is the period of time between the occurrence of a loss and the date the loss is reported to the Company. The length of the loss reporting lag affects our ability to accurately predict loss frequency (loss frequencies are more predictable for lines with short reporting lags) as well as the amount of reserves needed for incurred but not reported losses (less IBNR is required for lines with short reporting lags). As a result, loss reserves for lines with short reporting lags are likely to have less variation from initial loss estimates. For lines with short reporting lags, which include commercial automobile, primary workers’ compensation, other liability (claims-made) and property business, the key assumption is the loss emergence pattern used to project ultimate loss estimates from known losses paid or reported to date. For lines of business with long reporting lags, which include other liability (occurrence), products liability, excess workers’ compensation and liability reinsurance, the key assumption is the expected loss ratio since there is often little paid or incurred loss data to consider. Historically, the Company has experienced less variation from its initial loss estimates for lines of businesses with short reporting lags than for lines of business with long reporting lags.


	September 30,
(In thousands)	2022		2021
Net reserves at beginning of period	$	12,848,362	$	11,620,393


Net provision for losses and loss expenses:
Claims occurring during the current year (1)	4,260,179		3,598,969
Increase in estimates for claims occurring in prior years (2) (3)	54,632		1,552
Loss reserve discount accretion	24,835		23,109
Total	4,339,646		3,623,630
Net payments for claims:
Current year	643,908		547,082
Prior years	2,499,319		2,161,877
Total	3,143,227		2,708,959
Foreign currency translation	(193,755)		(53,935)
Net reserves at end of period	13,851,026		12,481,129
Ceded reserves at end of period	2,689,097		2,438,447
Gross reserves at end of period	$	16,540,123	$	14,919,576

(3) For certain retrospectively rated insurance policies and reinsurance agreements, reserve development is offset by additional or return premiums. Adverse development, net of additional and return premiums, was $37 million for the nine months ended September 30, 2022, and favorable development was $5 million for the nine months ended September 30, 2021, respectively.

The COVID-19 global pandemic has impacted, and may further impact, the Company’s results through its effect on claim frequency and severity. Loss cost trends have been impacted and may be further impacted by COVID-19-related claims in certain lines of business. Losses incurred from COVID-19-related claims have been offset, to a certain extent, by lower claim frequency in certain lines of our businesses; however, as the economy and legal systems have reopened, the benefit of lower claim frequency has continued to abate. Although as populations continue to be vaccinated against the virus and the effects of the pandemic have receded in many jurisdictions, most particularly the United States, the ultimate net impact of COVID-19 on the Company remains uncertain. New variants of the COVID-19 virus continue to create risks with respect to loss costs and the potential for renewed impact of the other effects of COVID-19 associated with economic conditions, inflation, and social distancing and work from home rules.

Most of the COVID-19-related claims reported to the Company to date involve certain short-tailed lines of business, including contingency and event cancellation, business interruption, and film production delay. The Company has also received COVID-19-related claims for longer-tailed casualty lines of business such as workers’ compensation and other liability; however, the estimated incurred loss impact for these reported claims are not material at this time. Given the continuing uncertainty regarding the pandemic's pervasiveness, the future impact that the pandemic may have on claim frequency and severity remains uncertain at this time.

The Company has estimated the potential COVID-19 impact to its contingency and event cancellation, workers’ compensation, and other lines of business under a number of possible scenarios; however, due to COVID-19’s continued evolving impact, there remains a high degree of uncertainty around the Company’s COVID-19 reserves. In addition, should the pandemic continue or worsen as a result of new COVID-19 variants or otherwise, governments in the jurisdictions where we operate may impose restrictions, including lockdowns, as well as renew their efforts to expand policy coverage terms beyond the policy’s intended coverage. Accordingly, losses arising from these actions, and the other factors described above, could exceed the Company’s reserves established for those related policies.

As of September 30, 2022, the Company had recognized losses for COVID-19-related claims activity, net of reinsurance, of approximately $348 million, of which $299 million relates to the Insurance segment and $49 million relates to the Reinsurance & Monoline Excess segment. Such $348 million of COVID-19-related losses included $343 million of reported losses and $5 million of IBNR. For the nine months ended September 30, 2022, the Company recognized current accident year losses for COVID-19-related claims activity, net of reinsurance, of approximately $4 million, of which $2 million relates to the Insurance segment and $2 million relates to the Reinsurance & Monoline Excess segment.

The adverse development for the Insurance segment primarily related to COVID-19 losses at two businesses. These businesses wrote policies providing coverage for event cancellation and film production delay which were heavily impacted by losses directly caused by the COVID-19 pandemic. Most of this COVID-19 related adverse development emerged during the third quarter as a result of settlements of claims at values higher than our expectations. However, the Company believes that as a result of these settlements the remaining level of uncertainty around the ultimate value of its known COVID-19 claims has been significantly reduced.

The adverse development mentioned above includes favorable prior year development for the Insurance segment primarily attributable to the 2020 and 2021 accident years and adverse development on the 2015 through 2019 accident years. The favorable development on the 2020 and 2021 accident years was concentrated in the other liability lines of business, including professional liability, products liability, commercial multi-peril liability and workers’ compensation. The Company experienced lower reported claim frequency in these lines of business during 2020 and 2021 relative to historical averages, and continues to experience lower reported incurred losses relative to our expectations for these accident years as they develop during 2022. These trends began in 2020 and we believe were caused by the impacts of the COVID-19 pandemic, including for example, lockdowns, reduced driving/traffic and increased work from home. Due to the ongoing uncertainty regarding the ultimate impacts of the pandemic on accident years 2020 and 2021 incurred losses, the Company has been cautious in reacting to these lower trends in setting and updating its loss ratio estimates for these years. As these accident years have continued to mature, the Company has continued to recognize some of the favorable reported experience in its ultimate loss estimates made during 2022.

The adverse development on the 2015 through 2019 accident years was concentrated in the other liability and professional liability, including medical professional, lines of business, as well as commercial auto liability. The development was driven by a larger than expected number of large losses reported. The Company believes social inflation is contributing to an increase in the frequency of large losses for these accident years. Social inflation can include higher settlement demands from plaintiffs, use of tactics such as litigation funding by the plaintiffs’ bar, negative public sentiment towards large businesses and corporations, and erosion of tort reforms, among others.

The overall slight adverse development for the Reinsurance & Monoline Excess segment was driven mainly by adverse development in the professional liability and non-proportional reinsurance assumed property and liability lines of business, substantially offset by favorable development in excess workers’ compensation. The adverse development was spread mainly across accident years 2015 through 2021 and was associated primarily with our U.S. assumed reinsurance business and related to accounts insuring construction projects and professional liability exposures. The favorable excess workers’ compensation development was mainly in 2011 and prior accident years, and was driven by a review of the Company’s claim reporting patterns as well as a number of favorable claim settlements relative to expectations.

During the nine months ended September 30, 2021, favorable prior year development (net of additional and return premiums) of $5 million included $8 million of favorable development for the Insurance segment, partially offset by $3 million of adverse development for the Reinsurance & Monoline Excess segment.

The overall favorable development for the Insurance segment was primarily attributable to favorable development on workers’ compensation business, partially offset by adverse development on professional liability business. The favorable workers’ compensation development was spread across many prior accident years, including prior to 2010, but was especially significant in accident year 2019. The favorable workers’ compensation development reflects a continuation of the benign loss cost trends experienced during recent years, particularly the favorable claim frequency trends. Our ongoing workers’ compensation claims management efforts, including active medical case management and use of networks and specialty vendors to control medical and pharmaceutical benefit costs, have also added to the favorable workers’ compensation prior year development. The adverse professional liability development was mainly concentrated in accident years 2016 through 2018 and was largely driven by higher than expected large losses being reported in the directors and officers and lawyers professional liability lines of business.

The adverse development for the Reinsurance & Monoline Excess segment was mainly driven by non-proportional reinsurance assumed liability business written in the U.K. for accident years 2016 through 2018, partially offset by favorable development on excess workers’ compensation business. The adverse development was driven by a greater than expected number of reported large losses.