NEW YORK (AdAge.com) -- PHD, Omnicom Group's second-largest media agency, will be led by a quartet of executives as it searches for a replacement for Matt Seiler, who is leaving his role as North America CEO to run rival Universal McCann, part of Interpublic Group of Cos.

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The interim team is comprised of managing partners Jean Neal, John Swift, Susan Taylor and Fred Foster, who works out of Canada. Mike Cooper, PHD's global CEO who is based in London, plans to spend about half his time in the U.S. offices. Peter Mears, another managing partner in North America, is going back to the U.K.

"In all honesty, I don't anticipate any impact on our existing business," Mr. Cooper said. "We are doing very well globally at the moment."

Mr. Seiler's hire was one of a flurry of moves by Interpublic. Mr. Seiler replaces Nick Brien, who will now run Interpublic's Mediabrands, a new umbrella organization for its media assets that houses the planning and buying assets of Universal McCann and Initiative.

For Omnicom's PHD, Mr. Seiler's departure is a big loss. It also came very quickly -- Mr. Seiler first met Mr. Brien during this spring's Venice Festival of Media -- and as a surprise to many at PHD, an executive close to the matter said. Mr. Seiler is largely credited with making PHD a legitimate player in the U.S., pulling in business from marketers such as New Balance, Jim Bean Brands and Charles Schwab Corp. Coupled with the financial troubles at its biggest client, Chrysler, it could be a rough path ahead for PHD.

Mr. Cooper said he believes the agency won't miss a beat, given what he calls a "very strong management group" in the North America. Mr. Cooper cited recent wins of New Balance's global media account and Cadbury in the U.K. and Ireland as proof that PHD is picking up global momentum since his appointment to the role of global CEO about nine months ago.