Rosenthal was named Interpublic media chairman and chief executive last May and was brought in to improve the group's media planning and buying business, having recently suffered the loss of its $3.5bn General Motors US account to Publicis Groupe, and its L'Oreal business in EMEA.
Since then, Rosenthal has recruited Arc Worldwide's Nick Brien to run Universal McCann and MediaVest's Richard Beaven to lead Initiative in North America.
This news will come at a troubling time for the group. Shares in Interpublic have steadily declined over the past year, reaching a 52-week low of $7.79 on the New York Stock Exchange this week.
The US-based Research Company Evaluating the Media Industry 2006 projections had Interpublic as the only major advertising network to undergo a media billings decline.
Interpublic has the fourth-largest media operation in terms of billings, with a 7.4% market share in the US behind leaders WPP Group, Publicis Groupe and Omnicom Group.
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