The agency plans to name a new managing partner as soon as this week, while top managers guide the office in the interim, an agency spokesman said.
Under Mr. Murphy’s tenure, the agency developed an integrated and media-neutral approach to marketing, operating several specialist units such as branding firm Landor and direct marketing agency Wunderman under one roof and one profit-and-loss structure.
The shop, however, suffered a number of blows since 2002, when Ford pulled its automotive brands Lincoln Mercury back to Detroit. Then, this year, it lost Ford's Jaguar account and the Sony Corp.'s Sony Electronics business.
Remaining clients include Ford's Land Rover North America, Callaway Golf Co. and Mattel. Recently, the agency picked up some business from Hilton Hotels. The agency has about 300 employees.
Mr. Murphy, 45, was unavailable for comment, but is expected to take another job in Southern California.
Y&R Irvine is part of Y&R Advertising, a unit of WPP Group.