Leader of Largest Unit of Interpublic Group Is Replaced, as Rumors Had Predicted

The widespread speculation that the Interpublic Group of Companies was planning to replace the leader of its largest division, the McCann Worldgroup, has turned out to be true, as rumors on Madison Avenue so often do.

Interpublic said on Tuesday afternoon that it had replaced Nick Brien, chairman and chief executive at the McCann Worldgroup since early 2010, with Harris Diamond, chairman and chief executive of another Interpublic division, the Constituency Management Group. Constituency Management oversees agencies like Weber Shandwick and FutureBrand, which handle tasks like public relations and brand identity consulting.

The change is effective immediately and, in keeping with the speculation that Interpublic executives had been dissatisfied with Mr. Brien for some time, a news release about the change devoted almost no attention to him and omitted the typical boilerplate that he was “leaving to pursue other interests.”

Nor was Mr. Brien - who le d the Interpublic media division, Mediabrands, before he took over the McCann Worldgroup - thanked for his services.

Under Mr. Brien, the McCann Erickson Worldwide unit of the McCann Worldgroup, which creates advertising campaigns for marketers, lost many high-profile clients like Exxon Mobil and Hewlett-Packard. There was also churn among senior managers, a significant decline in revenue and difficulties in landing new accounts.

On Tuesday afternoon, Interpublic also announced significant changes at McCann Erickson Worldwide, centered on the promotion of two executives, Luca Lindner and Gustavo Martinez, who will add major duties and join Mr. Diamond in a three-person office of the chairman at the McCann Worldgroup.

The trade publication Advertising Age, in an article this week, said, quoting unnamed “insiders,” that it would be surprising if Mr. Brien “wasn't gone by the start of 2013.”

Speculation about Mr. Brien's fate intensified last week when an article in The Wall Street Journal, quoting an unnamed “person familiar with the situation,” said that Interpublic executives were considering replacing Mr. Brien, perhaps “by the end of the year.”

The article described a possible effort to hire “a top executive from a rival ad agency” to replace Mr. Brien, but did not identify the executive. The shifting of Mr. Harris to the McCann Worldgroup may mean that the effort did not bear fruit.

Mr. Diamond was praised in the news release by Michael I. Roth, chairman and chief executive at Interpublic, who described Mr. Diamond as someone who “understands the business needs of global C.E.O.'s across a range of industries” and “has a proven track record of effectively managing a portfolio of agencies and growing the top line.”

Mr. Lindner and Mr. Martinez were named co-presidents for global brands at the McCann Worldgroup in March in a shift that was seen at the time as an attempt to help Mr. Brien with the care and feeding of clients. The two executives will now also have “full oversight of” McCann Erickson Worldwide, the news release said.

They will also continue to divide the oversight of large geographic regions in which the McCann Worldgroup does business, including the Americas, Europe and the Middle East.

Also, Andy Polansky, who had been president at Weber Shandwick, becomes chief executive, succeeding Mr. Diamond, who had also held that post in addition to his post as chairman and chief executive of the Interpublic agency group that includes Weber Shandwick.

The agency group that Mr. Diamond had led will now report directly to Interpublic executives.

Stuart Elliott has been the advertising columnist at The New York Times since 1991. Follow @stuartenyt on Twitter and sign up for In Advertising, his weekly e-mail newsletter.