Exhibit 15
November 9, 2012
Securities and Exchange Commission
100 F Street, N.E.
Washington, DC 20549
Commissioners:
We are aware that our report dated November 9, 2012 on our review of interim financial information of Arch Capital Group Ltd. and its subsidiaries (the “Company”) for the three-month periods ended September 30, 2012 and September 30, 2011 and included in the Company’s quarterly report on Form 10-Q for the quarter ended September 30, 2012 is incorporated by reference in the Registration Statement on Forms S-3 (Registration No. 333-158309, Registration No. 333-34499, Registration No. 333-82612, Registration No. 333-110190, Registration No. 333-117099, Registration No. 333-135421 and Registration No. 333-180329) and in the Registration Statements on Forms S-8 (Registration No. 033-99974, Registration No. 333-86145, Registration No. 333-72182, Registration No. 333-82772, Registration No. 333-98971, Registration No. 333-124422 and Registration No. 333-142835).
Very truly yours,
/s/ PricewaterhouseCoopers LLP
PricewaterhouseCoopers LLP, 300 Madison Avenue, New York, NY 10017
T: (646) 471 3000, F: (646) 471 8320, www.pwc.com/us