AM Best Co has affirmed at A- the financial strength rating of the operating units of Bermuda insurer Ironshore.The ratings agency also affirmed the company’s issuer credit rating of “bbb-” and declared a stable outlook for all ratings.The operating subsidiaries include Ironshore Insurance Ltd (Bermuda), Ironshore Indemnity Inc, Ironshore Specialty Insurance Company and Ironshore Europe Ltd.Best said the ratings reflect Ironshore’s strong risk-adjusted capitalisation, enhanced and developing business profile and highly experienced management team. Furthermore, the ratings recognise the progress made by the organisation, including optimisation of distribution channels in order to view a broad spectrum of submissions, which aids the company in selecting risks.Ironshore continues to build out its business, and at the end of 2010 Ironshore Europe was formed, which provides the organisation with a European operating platform.Best said that these strengths were partially offset by the group’s rapid pace of premium growth, particularly in casualty classes of business, during a soft phase of the casualty market.This growth creates reserve risk due to the uncertainty associated with measuring ultimate loss costs for those longer-tailed classes of business. In addition, Ironshore has continued credit risk from its dependence on reinsurance. The outlook recognises Best’s expectation that performance and risk-adjusted capitalisation will continue to support Ironshore’s operating strategies and growth initiatives.