Exhibit 15 6.30.15

We are aware that our report dated August 7, 2015 on our review of interim financial information of Arch Capital Group Ltd. and its subsidiaries (the “Company”) for the three-month and six-month periods ended June 30, 2015 and June 30, 2014 and included in the Company's quarterly report on Form 10-Q for the quarter ended June 30, 2015 is incorporated by reference in the Registration Statements on Forms S-3 (Registration No. 333-202440, Registration No. 333-180329) and in the Registration Statements on Forms S-8 (Registration No. 333- 99974, Registration No. 333-86145, Registration No. 333-82772, Registration No. 333-72182, Registration No. 333-98971, Registration No. 333-124422, Registration No. 333-142835, Registration No. 333-181308 and Registration No. 333-203993).