Carl Icahn launched a proxy battle to force Yahoo to reopen buyout talks with Microsoft, the billionaire investor said in a letter to the Internet company on Thursday.
Icahn has formed a 10-member rival slate for Yahoo's board to push the company to accept a $33-per-share, or $47.5 billion, offer from Microsoft.
Microsoft abruptly abandoned its bid after balking at Yahoo's $37-per-share asking price.
Icahn also disclosed in the letter to Yahoo Chairman Roy Bostock that he has acquired 59 million shares and has sought antitrust clearance from the U.S. Federal Trade Commission to acquire up to about $2.5 billion worth of Yahoo Stock.
"It is clear to me that the board of directors of Yahoo has acted irrationally and lost the faith of shareholders and Microsoft," Icahn wrote.
Icahn's slate of nominees includes himself, Frank Biondi, a former Viacom chief, and Keith Meister, vice chairman of Icahn Enterprises.
Mark Cuban, Dallas Mavericks basketball team owner and co-founder of cable network HDNet is also on Icahn's slate. Cuban is also familiar with Yahoo's negotiating style after he sold Broadcast.com to Yahoo in 1999 for about $5 billion.
Other nominees include Lucian Bebchuk, professor of law, economics and finance at Harvard Law School; John Chapple, president of Hawkeye Investments; and telecoms industry veteran and former chief executive of Nextel Partners; Adam Dell, managing partner of Impact Venture Partners; Edward Meyer, CEO of Ocean Road Advisors and former CEO of advertising firm Grey Global Group; Brian Posner, a former CEO of ClearBridge Advisors LLC; and Robert Shaye, the former co-CEO of Time Warner's New Line Cinema.