The underwriting gain in the current quarter reflected a GAAP combined ratio of 90.3 percent, as compared to 104.5 percent in the prior year quarter. This improvement of 14.2 points in the combined ratio was primarily due to lower catastrophe losses (9.2 points) and higher underlying underwriting margins (4.9 points). Catastrophe losses in the current quarter were primarily driven by increases in estimated losses related to wind and hail storms that occurred in the second quarter 2012. Also included in the current quarter underwriting gain was net favorable prior year reserve development in all three segments.
The current quarter underlying underwriting gain, which excludes net favorable prior year reserve development and catastrophe losses, reflected a GAAP combined ratio of 92.1 percent, as compared to 97.0 percent in the prior year quarter. This improvement of 4.9 points primarily resulted from lower non-catastrophe weather-related losses as well as earned rate increases exceeding loss cost trends.
Total revenues of $6.512 billion in the current quarter increased $105 million or 2 percent from the prior year quarter. Within total revenues, earned premiums and net investment income increased $61 million and $32 million, respectively. The modest increase in net investment income was due to the non-fixed income portfolio driven by real estate partnerships and hedge fund performance. Net investment income in the fixed income portfolio decreased slightly from the prior year quarter primarily due to lower reinvestment rates.
Net written premiums of $5.697 billion in the current quarter were approximately the same as the prior year quarter. Renewal rate gains continued across all segments. Retention rates remained strong across each segment and were generally consistent with recent quarters. New business volumes were lower than the prior year quarter in all segments, largely as a result of the company’s pricing strategy. Net written premiums in Business Insurance 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.