A.M. Best Co. has upgraded the issuer credit ratings (ICR) to “a+” from “a” and affirmed the financial strength rating (FSR) of A (Excellent) of Allied World Assurance Company, Ltd (Allied World) and its operating affiliates. The outlook for the ICRs has been revised to stable from positive, while the outlook for the FSR is stable. A.M. Best also has assigned an FSR of A (Excellent) and an ICR of “a+” to Allied World’s reinsured subsidiary, Vantapro Specialty Insurance Company (headquartered in Farmington, CT). The outlook assigned to both ratings is stable. Concurrently, A.M. Best has upgraded the ICRs to “bbb+” from “bbb” of the ultimate parent, Allied World Assurance Company Holdings, AG (AWH) (Switzerland) (NYSE:AWH), and its downstream holding company Allied World Assurance Company Holdings, Ltd (Allied World Holdings Bermuda). A.M. Best also has upgraded the debt ratings to “bbb+” from “bbb” of Allied World Holdings Bermuda. The outlook for these ratings has been revised to stable from positive. All the above companies are domiciled in Bermuda, unless otherwise specified. (See below for a detailed listing of the companies and debt ratings.) Allied World is a property/casualty insurer/reinsurer with significant geographic reach. The ratings reflect its diversified mix of business, excellent risk-adjusted capitalization, experienced management team and comprehensive enterprise risk management framework. The stable outlook on the ratings reflects Allied World’s consistently strong operating performance, proven risk management culture and successful track record of expansion in terms of geography, products and distribution. These positive rating attributes have placed Allied World in a very strong position to successfully execute its business plans. The breadth of Allied World’s operations has been enhanced while it has delivered strong results over the long term. Partially offsetting these positive rating factors is Allied World’s casualty orientation, as pricing for this class of business is cyclical and presently very competitive. The longer-tail nature of this business lends to greater uncertainty as regards to rate adequacy, which is exacerbated by the current low interest rate environment. Nonetheless, Allied World has chosen a targeted business strategy while taking steps to refine its cycle management capability. Allied World’s continued focus on casualty business also has helped to limit its exposure to the global catastrophes that have taken place over the past few years. Furthermore, Allied World appears to have a prudent reserving philosophy, maintaining a significant cushion of incurred but not reported reserves. This conservative reserving posture has enabled the company to consistently recognize favorable loss reserve development for several years, which has contributed to its strong operating returns through the current soft phase of the casualty market. Accordingly, the outlook is medium term in nature to allow more recent accident years to mature given the current soft pricing dynamics of the casualty market.