Arch Capital Group has topped Wall Street expectations for the sixth quarter in a row.Analysts expected Arch to come in last night with earnings of 82 cents per share on revenues of $757.7 million, but the company beat those estimates by 20 cents, reporting earnings per share of $1.02 and revenues of $842.5 million.Revenue was up 8.6 percent from $775.6 million in the second quarter of last year — also beating analysts’ projections.The Bermuda-based re/insurer also posted a net income of $212.6 million or $1.54 per share for the three months ending on June 30 — more than doubling the $90.1 million or $0.65 per share it reported in Q2 of 2011.The company’s book value per share was $34.45 at June 30, 2012 — a 3.4 percent increase from the $33.33 per share at the end of Q1 of this year and an 8.5 percent increase from the $31.76 per share at the end of Q4 2011.In terms of price changes of Arch stock, the best recent streak was when it gained $2.86 per share between June 25 and July 3 of 2012.For the second quarter of 2012, the company reported a combined ratio of 87.2 percent — better than the 100 percent it reported in the same period of 2011. The combined ratio measures profitability, excluding investment income, and is the sum of the loss ratio and expense ratio. A combined ratio under 100 percent represents an underwriting profit.The combined ratio of the company’s insurance and reinsurance subsidiaries consisted of a loss ratio of 55 percent and an underwriting expense ratio or 32.2 percent in Q2 of 2012, compared to a loss ratio of 67.1 percent and an underwriting expense ratio of 32.9 percent for the 2011 second quarter.Gross premiums written by the insurance segment in the 2012 second quarter were 6.5 percent higher than in the 2011 second quarter, while net premiums written were six percent higher than in the 2011 second quarter. The growth in net premiums written reflected increases in programmes, professional liability and construction business, partially offset by a lower level of onshore energy business (included in the ‘property, energy, marine and aviation’ line). The higher level of programme business was primarily due to growth in exposures on existing accounts and rate improvements while the higher level of professional liability business primarily resulted from an increase in international small and medium sized accounts.Net premiums earned by the insurance segment in the 2012 second quarter were 8.7 percent higher than in the 2011 second quarter, and reflect changes in net premiums written over the previous five quarters.The 2012 second quarter loss ratio reflected minimal current year catastrophic event activity, with a low level of current quarter activity and a reduction in amounts recorded for 2012 first quarter storm activity, compared to 8.0 points in the 2011 second quarter.In April 2012, Arch completed the acquisition of the credit and surety reinsurance operations of Ariel Reinsurance Company Ltd. based in Zurich, Switzerland. In the transaction the company acquired $83.1 million of net unearned premiums along with other insurance balances. Under applicable accounting rules for business combinations, the recording of such unearned premiums was not reflected as net premiums written but will result in net premiums earned (primarily over a two-year period). Net premiums earned for the 2012 second quarter included $17.3 million related to the acquired net unearned premiums.Gross premiums written by the reinsurance segment in the 2012 second quarter were 35.7 percent higher than in the 2011 second quarter, while net premiums written were 32.6 percent percent higher than in the 2011 second quarter, primarily due to increases in other speciality, property catastrophe and mortgage business.The growth in other speciality primarily resulted from new business written in UK motor while the higher level of property catastrophe primarily resulted from new business and share increases in Florida, Japan and other international risks. The mortgage business primarily resulted from a reinsurance treaty written in the 2012 second quarter which covers newly originated residential mortgages beginning in October 2011.For the 2012 second quarter, such business contributed $21.6 million of premiums written of which $13.5 million related to the period from October 2011 to March 2012. Net premiums earned in the 2012 second quarter were 20.7 percent higher than in the 2011 second quarter, and reflect changes in net premiums written over the previous five quarters, including the mix and type of business written. In addition, net premiums earned included $17.3 million related to the credit and surety business acquired in April 2012.