NEW YORK (CNN/Money) - Ted Turner, the largest shareholder in AOL Time Warner Inc., has become a leader in the effort to remove company Chairman Steve Case, according to a published report Tuesday.

The New York Times, quoting unidentified people close to both men, said that Turner has grown increasingly upset with the performance of the company's America Online Internet service provider unit, the investigation into AOL's accounting practices during the period before its merger with Time Warner closed, and the decline in AOL Time Warner's stock price. CNN/Money is a unit of AOL Time Warner.

Turner, the vice chairman of the company, owns 148.4 million shares, or 3.6 percent of shares outstanding, according to the company's March proxy statement, although the company has reported that he has sold more than 10 million shares since that filing. The roughly 75 percent decline in the share price from the time the merger closed in January of 2001 has cost Turner about $5 billion personally.

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The Times said that Turner had been supportive of Case until a Washington Post report this past summer detailed questions about how AOL accounted for some of its advertising and commerce revenue. Federal authorities are now looking into those questions, which has helped depress the company's stock price. Company executives have denied any wrongdoing by the company.

The paper said Turner did not call for Case's removal at a board of directors meeting in September. It said Turner met with AOL Time Warner CEO Richard Parsons before the meeting and agreed not to focus on management changes at this time. But it also said efforts to remove Case have not ended and could come to a head at the May shareholders meeting.

The paper said Turner, who was traveling in China, was not available for comment on the story and that Case declined to comment.