If you've been an investor for any length of time, you know how many events can cause a stock to drop: Bad earnings, analyst downgrades, interest rate rumors, short sellers -- the list goes on and on. But here's an event you may not have pegged as a cause for your stock's recent slide: Your CEO just bought a palatial new estate.

Alas, according to recent research by Professors Crocker Liu and David Yermack, "Future company performance deteriorates when CEOs acquire extremely large or costly mansions and estates." Why? Because it signals entrenchment -- fat cats ready to rest on their laurels.

Not that there's anything wrong with that
While richly rewarded CEOs have come under fire of late, far be it from me to begrudge someone the opportunity to live large. Instead, the reason I find the Liu/Yermack study so interesting is that identifying engaged leadership is one of the best ways for individual investors to buy into the best-performing stocks of the next decade or more.

Indeed, some of the most impressive operators in the market, including Morningstar (NASDAQ:MORN), Nike (NYSE:NKE), and Google (NASDAQ:GOOG), are run by dedicated founders/CEOs who own a slug of shares and have something to prove.

Still, I fully expect the leaders of each of these companies to someday move on. When that happens, the entrepreneurial spirit that has spurred each company will depart as well.

What happens when zealots move on
For evidence of the consequences here, consider the cases of Dell (NASDAQ:DELL) and Microsoft (NASDAQ:MSFT). Michael Dell and Bill Gates, respectively, founded each of these companies and built them into global giants. As their visions reached fruition, early shareholders earned 100 to 200 times their money along the way.

But look at what's happened since Gates stepped down as CEO in 2000, and Dell in 2004: Both stocks have stagnated.

While Dell recently stepped back into the CEO role of his company, Gates announced that he is stepping down entirely from a full-time role at Microsoft to focus on his work at the Bill & Melinda Gates Foundation. This is wonderful news for Gates, his wife, the foundation, and the people the foundation will help -- but not so much for Microsoft shareholders.

Contrast that situation with that of another stock that's been stagnant recently: Berkshire Hathaway (NYSE:BRK-A). As the Liu/Yermack study notes, Warren Buffett continues to live in the Omaha house he purchased in 1958 for $31,500. Moreover, when it came time for Buffett to give some of his fortune away, he announced that he would donate it to the Gates Foundation, rather than set up his own organization. And despite overtures from President Obama, Buffett has said he has no interest in being Secretary of the Treasury. In other words, this is a founder/CEO still focused on his work.

The Foolish bottom line
Engaged and entrepreneurial CEOs are among an individual investor's best friends in the marketplace. Of course, swanky home purchases or new endeavors aren't the only indicators of a CEO who is no longer fully focused. That's why you need to watch the leadership of your companies as closely as you do the financials.

At our Motley Fool Hidden Gems small-cap investing service, we believe that the leadership effect is even more amplified when it comes to small companies. And when you combine great leadership with a wide market opportunity, you have the opportunity for huge returns.

These are precisely the situations we seek out at Hidden Gems. If you'd like to see the stocks we're recommending today, click here to join Hidden Gems free for 30 days. There is no obligation to subscribe.

This article was first published on April 17, 2007. It has been updated.

Tim Hanson owns shares of Berkshire Hathaway. The Motley Fool owns shares of Berkshire and Morningstar. Dell, Microsoft, and Berkshire Hathaway are Motley Fool Inside Value recommendations. Morningstar and Berkshire are Stock Advisor picks. Google is a Rule Breakers selection. The Fool's disclosure policy is the one who wants to be with you. Deep inside, it hopes you feel it too.