Exhibit 15

November 3, 2017

Securities and Exchange Commission

100 F Street, N.E.

Washington, DC 20549

Commissioners:

We are aware that our reportsdated May 5, 2017, August 4, 2017, November 3, 2017 on our review of interim financial information of Arch Capital Group Ltd.(the “Company”), which are included in the Company's quarterly report on Form 10-Q for the quarter ended March 31, 2017, June 30, 2017, and September 30, 2017, are incorporated by reference in this Registration Statement on Form S-3.

Very truly yours,

/s/ PricewaterhouseCoopers LLP