Yahoo! Inc. said Chief Executive Officer Scott Thompson is stepping down after failing to correct errors in his credentials and the company is revamping its board, handing a victory to activist investor Daniel Loeb, who had pushed for the overhaul and said the Web portal is mismanaged.

Ross Levinsohn, Yahoo's head of global media, was named interim CEO, and director Fred Amoroso will become chairman, the Sunnyvale, California-based company said in a statement yesterday. Amoroso replaces Roy Bostock, the non-executive chairman, who is exiting the board immediately. Yahoo agreed to add Loeb to its board along with two other directors nominated by his fund, Third Point LLC, to end a proxy fight.

Third Point, which owns about 5.8 percent of Yahoo, stepped up pressure on Yahoo since flagging discrepancies in Thompson's resume on May 3. The departure of Yahoo's third CEO in just over three years adds to upheaval at a company that was once a leader in Web search and online information. Yahoo's sales tumbled 31 percent last year from a peak three years earlier, and its market value has dropped by more than half since the end of 2005.