Arch Capital Group is a holding company. Through its subsidiaries and, through operations in Bermuda, the U.S., Europe and Canada, Co. writes lines of property and casualty insurance and reinsurance, as well as mortgage insurance and reinsurance. Co.'s segments are: insurance, which writes business on both an admitted and non-admitted basis; reinsurance, which writes business on both a proportional and non-proportional basis and writes both treaty and facultative business; and mortgage, which operations include U.S. and international mortgage insurance and reinsurance operations as well as government sponsored enterprise credit risk-sharing transactions.