Simon Sherwood, chief executive of BBH, said: "Steve leaves BBH with the immense respect and gratitude from his US and global management colleagues for all that he has done for the agency over the past five years."
Harty joined BBH in 2005 as agency chairman in an effort to raise the agency’s profile. In early 2010, BBH restructured its management and moved him to group chairman.
According to BBH, in the current market, they have decided to focus on strengthening its integrated agency offering through organic growth and continued partnerships; however, Harty’s business philosophy was based on acquisition, and in order to pursue that end, he has left BBH.
Harty will leave BBH in mid-August, only months after taking the position as group chairman.
Before BBH, Harty was co-founder and CEO of Merkley Newman Harty, now part of the Omnicon Group under the name Merkley and Partners. He was also at Ogilvy & Mather for over a decade.
He leaves just after General Motors pulled their $270m Cadillac account from BBH and handed it to Fallon.