The underwriting gain in the current quarter reflected a GAAP combined ratio of 93.3 percent, as compared to 105.4 percent in the prior year quarter. This improvement of 12.1 points in the combined ratio was primarily due to higher underlying underwriting margins (6.5 points) and lower catastrophe losses (5.1 points). Also included in the current quarter underwriting gain was net favorable prior year reserve development which primarily resulted from better than expected loss experience in property-related coverages largely for accident years 2009-2011 and in the general liability product line for accident years 2003-2009. These improvements were partially offset by a $108 million after tax ($167 million pre tax) increase to asbestos reserves, which was consistent with the prior year quarter.
The asbestos reserve strengthening in the current quarter was primarily driven by increases in the company’s estimate for projected settlement and defense costs related to a broad number of policyholders and higher projected payments on assumed reinsurance accounts. The increase in the estimate of projected settlement and defense costs resulted from recent payment trends being moderately higher than previously anticipated due to the impact of the current litigation environment. Notwithstanding these payment trends, the company’s overall view of the underlying asbestos environment is essentially unchanged from recent periods and there remains a high degree of uncertainty with respect to future exposure from asbestos claims.
The current quarter underlying underwriting gain, which excludes net favorable prior year reserve development and catastrophe losses, reflected a GAAP combined ratio of 93.0 percent, as compared to 99.5 percent in the prior year quarter. This improvement of 6.5 points primarily resulted from earned rate increases exceeding loss cost trends and lower non-catastrophe weather-related losses.
Business Insurance net written premiums of $2.962 billion in the current quarter increased 5 percent from the prior year quarter primarily driven by continued increases in renewal rate change. Retention rates remained strong and increased from recent quarters. New business volumes were lower than the prior year quarter, consistent with the company’s pricing strategy. Net written premiums also benefited from continued positive exposure change at renewal, as well as a meaningfully higher level of positive audit premiums compared to the prior year quarter.