Arch Capital Group Ltd. (NASDAQ: ACGL) reports that net income available to common shareholders for the 2011 third quarter was $162.5 million, or $1.19 per share, compared to $141.6 million, or $0.92 per share, for the 2010 third quarter. The Company also reported after-tax operating income available to common shareholders of $107.4 million, or $0.78 per share, for the 2011 third quarter, compared to $130.7 million, or $0.85 per share, for the 2010 third quarter. All earnings per share amounts discussed in this release are on a diluted basis. All information in this release has been adjusted to reflect the three-for-one share split effected in May 2011. The Company’s book value per common share was $31.20 at September 30, 2011, a 0.6% increase from $31.00 per share at June 30, 2011 and a 4.0% increase from $29.99 per share at December 31, 2010. The Company’s after-tax operating income available to common shareholders represented a 10.4% annualized return on average common equity for the 2011 third quarter, compared to 12.3% for the 2010 third quarter. After-tax operating income available to common shareholders, a non-GAAP measure, is defined as net income available to common shareholders, excluding net realized gains or losses, net impairment losses recognized in earnings, equity in net income or loss of investment funds accounted for using the equity method and net foreign exchange gains or losses, net of income taxes. See page 7 for a further discussion of after-tax operating income available to common shareholders and Regulation G. The Company’s 2011 third quarter results included losses for current year catastrophic events of $59.6 million, net of reinsurance and reinstatement premiums, compared to $24.2 million in the 2010 third quarter. The 2011 third quarter amounts included $45.5 million for catastrophic events that occurred in the quarter, primarily related to Hurricane Irene and the Denmark floods, and $14.1 million related to net increases in loss estimates on catastrophic events that occurred in the first six months of 2011. The Company’s preliminary estimates for these events are based on currently available information derived from modeling techniques, industry assessments of exposure, preliminary claims information obtained from the Company’s clients and brokers to date and a review of in-force contracts. The Company’s actual losses from these events may vary materially from the estimates due to the inherent uncertainties in making such determinations resulting from several factors, including the preliminary nature of available information, the potential inaccuracies and inadequacies in the data provided by clients and brokers, the modeling techniques and the application of such techniques, the contingent nature of business interruption exposures, the effects of any resultant demand surge on claims activity and attendant coverage issues. In addition, actual losses may increase if the Company’s reinsurers or retrocessionaires fail to meet their obligations to the Company or the reinsurance protections purchased by the Company are exhausted or are otherwise unavailable.