Steve Case, a founder of America Online (AOL) and a key player in its troubled merger with Time Warner, has resigned from the media giant's board.
Time Warner has suffered since it merged with America Online
Mr Case said he was stepping down to spend more time on his new investment company Revolution.
Time Warner merged with internet service provider AOL in 2000 in what was the world's largest media deal.
Since then the firm's shares have tumbled and investors have questioned the wisdom of the merger.
Many of the other key executives involved in the deal have already left the company.
Speculation has surrounded the future of AOL, despite reassurances from Time Warner chairman and chief executive Dick Parsons that he is committed to the firm.
Richard Parsons is charged with reviving Time Warner's fortunes
Recent reports suggested Time Warner may sell a stake in AOL to software firm Microsoft.
Many investors have complained that the value of Time Warner's share price is being depressed by its ownership of AOL.
In his leaving statement Mr Case defended AOL, saying that the firm "can return to its past greatness".
He added that by resigning he would avoid "any potential conflicts of interest as Revolution moves into new areas".