Allied World Assurance Company Holdings, Ltd is a Bermuda-based specialty insurance and reinsurance company that underwrites a diversified portfolio of property and casualty insurance and reinsurance lines of business through operations in Bermuda, the United States, Ireland, Switzerland and the United Kingdom. On October 20, 2008, the Company acquired Darwin Professional Underwriters, Inc. (Darwin). It operates in three geographic markets: Bermuda, Europe and the United States. Its Bermuda insurance operations focus primarily on underwriting risks for United States domiciled clients and other clients with complex insurance needs. European operations focus predominantly on property and casualty insurance for European and international accounts. The United States operations focus on the middle-market companies. It has offices in Atlanta, Boston, Costa Mesa, Chicago, Dallas, Farmington, Los Angeles, New York City, San Francisco and St. Petersburg.