Icahn Should Hang It Up: Activist

Steve Ballmer politely listened to him and then apparently stopped taking his calls. Carol Bartz has dissed him from the get-go of her tenure as CEO. She proclaimed to Forbes last year : "Icahn is just another shareholder. What's he going to do, fire me?"

Whether he realizes it or not, this attitude is probably the most damaging thing to Icahn going forward as an activist investor. CEOs and corporate boards will no longer see him as "Carl Icahn: Corporate Raider of the 80s" but "Carl Icahn: Has Been." In their eyes, he'll be Icahn't, not Icahn.

Carl Icahn will always have a reputation as a successful investor. Forbes recently pegged his net worth at $9 billion. Yet, it's unclear whether his hedge fund, Icahn Partners, will continue after his death.

While George Soros, 79, and Julian Robertson, 77, have repeatedly developed talented managers (like Stanley Druckenmiller, Lee Ainslie, and John Griffin) who go on to successful careers, Icahn, 73, has not. If Icahn was hit by the proverbial bus tomorrow, it's unclear that Icahn Partners could or would continue.

Icahn will always be able to grab the headlines with some outrageous comment about a CEO because he's become the "poster boy" for activist investing. He could keep running money and probably will. However, as he takes his leave from Yahoo!, it appears as though his most influential days as an activist investor are behind him and not in front of him.

-- Written by Eric Jackson in Naples, Fla.