Icahn wanted Yahoo to strongly consider the Microsoft bid and has now put up ten of his own nominees to help run the company, as well as be more sympathetic to his own substantial stake in Yahoo.
In an open letter to Yahoo chairman Roy Bostock, Icahn slammed the way Yahoo handled the Microsoft bid out of hand.
"It is unconscionable that you have not allowed your shareholders to choose to accept an offer that represented a 72% premium over Yahoo's closing share price on the day before the initial Microsoft offer." writes Icahn.
He says, "I and many of your shareholders strongly believe that a combination between Yahoo and Microsoft would form a dynamic company, and more importantly would be a force strong enough to compete with Google on the internet."
Microsoft has now shelved plans to launch a hostile takeover of Yahoo.