Arch Capital (ACGL) 10-Q 2014 Q3 Quarterly report

Exhibit 15

Securities and Exchange Commission

100 F Street, N.E.

Washington, DC 20549

Commissioners:

We are aware that our report dated November 7, 2014 on our review of interim financial information of Arch Capital Group Ltd. and its subsidiaries (the “Company”) for the three-month and nine-month periods ended September 30, 2014 and September 30, 2013 and included in the Company's quarterly report on Form 10-Q for the quarter ended September 30, 2014 is incorporated by reference in the Registration Statement on Form S-3 (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 and Registration No. 333-181308).

Very truly yours,

/s/ PricewaterhouseCoopers LLP

New York, New York

November 7, 2014