Pittman, who was also AOL Time Warner's joint chief operating officer with Richard Parsons, had been the most strident advocate of integrating AOL and Time Warner's division. However, his departure leaves the traditional media Time Warner division as the dominant partner.
The advertising recession effectively put an end to Pittman's ambitions that had surfaced when AOL paid $160 billion to take over Time Warner.
The first 18 months of the merged company's existence have not been particularly harmonious, as it has struggled to convince the financial community that its combined business is worth more than the sum of its parts.
Following Pittman's departure, Parsons has promoted a number of executives from the Time Warner side of the business. Don Logan, the head of Time Inc, and Jeffrey Bewkes, the chairman of HBO, have taken on broader operational roles, leading to speculation that the company will retreat from the integration model envisaged by Pittman.