Ted Turner, who had been increasingly marginalized by the leadership of Time Warner since he sold Turner Broadcasting to the company in 1996, will step down from its board after its upcoming annual meeting, he said on Friday. In a statement, Turner, who remains Time Warner's largest individual shareholder, gave no reason for his decision, saying only that he had reached it "after much deliberation." Some analysts speculated that Turner may have been particularly upset over Time Warner's recent decision to sell some of the businesses that had long been an integral part of the Turner Broadcasting empire, including its sports teams and a sports cable network.