Arch Reinsurance Ltd. (Arch) (Bermuda) and its strategic affiliates have had their outlook revised to positive from stable and been affirmed the financial strength rating (FSR) of A (Excellent) and issuer credit ratings (ICR) of “a+” by AM Best Co.Best has also revised the outlook to positive from stable and affirmed the ICRs of “bbb” and “bbb+” of Arch Capital Group (US) Inc. and the ultimate holding company, Arch Capital Group Ltd., respectively, as well as all debt ratings of Arch Capital Group Ltd.The ratings agency said that the revised outlook reflected Arch's continued superior operating performance, consistently excellent capitalisation and demonstrated risk management prowess. It said that Arch maintained a very strong underwriting culture, which focuses on active cycle management and being adaptive to varied market conditions.Best added that overall operating results since Arch's inception had been strong and in certain instances have exceeded most peers in the sector. Typically, Arch has had a smaller share of major industry losses, which demonstrates the superior risk management of the company, it said.Furthermore, the ratings agency said that Arch had a prudent investment portfolio and conservative reserving philosophy, which helped to maintain a strong balance sheet.Partially offsetting these positive rating attributes, however, it said were the current soft market conditions in which Arch, as well as all industry participants, must navigate.The FSR of A (Excellent) and ICRs of “a+” have been affirmed for Arch Reinsurance Ltd. and its affiliates Arch Reinsurance Company, Arch Insurance Company, Arch Specialty Insurance Company, Arch Excess & Surplus Insurance Company, and Arch Insurance Company (Europe) Ltd.