When David Einhorn speaks, the smart money listens. The founder and president of Greenlight Capital, a long-short hedge fund, Einhorn is best known for his bear call on Lehman Brothers before its 2008 collapse. His impressive track record has earned him the top slot among Wall Street investors tracked by The Motley Fool's CAPS service.

Einhorn is back in the headlines for two reasons. He's negotiating to buy a roughly $200 million stake in the New York Mets, and he's also calling for Microsoft (Nasdaq: MSFT) to replace CEO Steve Ballmer. Microsoft was Greenlight's eighth-largest position at the end of March, at 9,069,042 shares worth $230 million.

No doubt Einhorn has thought a lot about what will drive the stock up. He told fellow fund managers at a New York investment conference that Ballmer is stuck in the past and that Ballmer's "continued presence is the biggest overhang on Microsoft's stock."

Microsoft's board, including Chairman and co-founder Bill Gates, is backing Ballmer. But then, what would you expect? Not only were Ballmer and Gates college buddies, but it's bad management to publicly show a lack of support for your CEO.

The bigger issue is finding someone who can do a better job. Upgrading CEOs has a mixed history.

Wall Street certainly thinks the right CEO can make a difference. Apple (Nasdaq: AAPL) CEO Steve Jobs is so well regarded that the company's stock price fluctuates on news of his health. Hewlett-Packard's (NYSE: HPQ) stock price rose more than 10% intraday on news that CEO Carly Fiorina was being forced out. HP stock then popped several months later on news that Mark Hurd was joining as CEO and plummeted 10% last August upon his sudden departure.  Oracle (Nasdaq: ORCL) stock subsequently rose 5% on news that Hurd was joining as co-president.

But although HP's stock doubled during Hurd's five-year tenure, it now looks as though IBM's (NYSE: IBM) CEO was right when he said Hurd took cost-cutting too far at HP. And while investors called for Dell (Nasdaq: DELL) founder and Chairman Michael Dell to replace then-CEO Kevin Rollins for more than a year before he did so in January 2007, the company continued to flail. (There are recent signs that it may be turning.)

Foolish takeaway
Mark Hurd succeeded at HP on execution and cost-cutting skills. Microsoft's challenge is different. It needs management that can lead it through the kind of transformation IBM began about 20 years ago with Lou Gerstner at the helm.

Will Microsoft find and hire its "Lou Gerstner"? An easy way to stay on top of market developments is The Motley Fool's free new My Watchlist feature. You can get up-to-date news and analysis by adding these stocks to your Watchlist now.