Arch Capital Group Ltd. (Arch Capital or ACGL) is a Bermuda-based public limited company which writes insurance, reinsurance and mortgage insurance on a worldwide basis, with a focus on specialty lines, the segment of the insurance industry where the more difficult and unusual risks are written.

It has operations in Bermuda, the United States, Canada, Europe, Australia[1] and, in the case of mortgage insurance, Hong Kong.

[5][6] Following the event of September 11, 2001, Arch Capital launched an underwriting initiative to address the global demand for insurance and reinsurance capacity.

[14] In 2022, Arch Capital was added to the Standard & Poor's (S&P) 500 Index, replacing Twitter (now X).

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