Arch Insurance Group Names Thomas McMahon Executive Vice President and Northeast Regional Manager

NEW YORK--(BUSINESS WIRE)--Aug. 12, 2003--Arch Insurance Group, a division of Arch Capital Group Ltd., today announced that Thomas McMahon has been named to the position of Executive Vice President in charge of the Northeast Region, beginning August 18. In his new role, Mr. McMahon will focus on opening Arch's Northeast regional office and growing all lines of business in this sector. Mr. McMahon will be based in New York and will report to Ralph Jones, president and CEO, Arch Insurance Group.

"We are very pleased to have a person of Tom's caliber join the Arch team. His vast insurance expertise and abilities will contribute to the growth of our Northeast operations. The addition of Tom in New York also completes our regional office network, which currently includes offices in Atlanta, Chicago and San Francisco. This also aligns our underwriting plans with our distribution management," said Mr. Jones.

Mr. McMahon joins Arch with more than 30 years of insurance industry expertise. Prior to Arch, Mr. McMahon served as Executive Vice President of Royal & SunAlliance's U.S. Operations, where he most recently managed all of the corporate and producer relationships in the U.S. During his tenure at Royal & SunAlliance he held a variety of senior-level management positions, including Chief Marketing Officer and Area President. Mr. McMahon began his insurance career at The Hartford.

Arch Insurance Group is a division of Arch Capital Group Ltd., a Bermuda-based company that provides insurance and reinsurance on a worldwide basis through its wholly owned subsidiaries. Arch Insurance Group's principal insurance subsidiaries - Arch Insurance Company, Arch Specialty Insurance Company and Arch Excess & Surplus Insurance Company - are rated A- (Excellent) by A.M. Best. For more information, visit www.archinsurance.com.

Cautionary Note Regarding Forward-Looking Statements

The Private Securities Litigation Reform Act of 1995 provides a "safe harbor" for forward-looking statements. This release or any other written or oral statements made by or on behalf of Arch Capital Group Ltd. and its subsidiaries (collectively, the "Company") may include forward-looking statements which reflect the Company's current views with respect to future events and financial performance. Forward-looking statements involve the Company's current assessment of risks and uncertainties, which may cause actual events and results and prospects to differ materially from those expressed or implied in these statements. Certain information regarding such risks and uncertainties is set forth in the Company's filings with the Securities and Exchange Commission. The Company undertakes no obligation to publicly update or revise any forward-looking statement, whether as a result of new information, future events or otherwise.