'It's too big a job for me to do myself,' Richard Edelman said about handing off the president role to Harrington.
EVP Rema Vasan, MSL's global lead for P&G, will lead the new service.
Marketers may think twice about the platform after revelations in The New York Times, according to analyst.
International president Alan VanderMolen is leaving the agency.
The former WPP CEO has told a New York audience that he's not planning to retire.