Earlier this week, the Value Investing Congress took place in New York. The Congress invites some of the world’s most prestigious investors to give their best stock ideas. Among some of the famous investors who spoke were David Einhorn and Bill Ackman. Investors and wannabe investors alike listen to every word these famous money managers say. By the time a presentation is done, a stock could move by double digits.

Einhorn is known for moving stocks the most. The Wall Street Journal actually did a study that showed that when Einhorn makes negative comments about a company, the stock falls sometimes as much as 20 percent.

In fact, one analyst stated there was a 50 percent chance that Einhorn would speak negatively about one particular stock, Herbalife — which Einhorn had just asked questions about in the past. Based on that alone, the analyst downgraded the stock price target!

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Einhorn has gained a bit of a cult following, but there is more to the story. Interestingly, he spoke this past Tuesday and had some harsh words for those who try to mimic his investing.

He began talking about an anonymous “influential investor” who in 1996 purchased shares in a company called Cityscape and presented it at the Barron’s Roundtable. The stock then tanked, but the anonymous investor admitted the mistake. Einhorn stated that he learned an important lesson from this: when it comes to investing, “do your own homework.” He reiterated to never blindly follow a famous investor into a stock.

Einhorn thinks it is crazy analysts are forecasting what he will say next and basing their investment decisions on that. Einhorn, who is a big sports fan, compared these so-called analysts with the NFL replacement referees. During his speech, he specifically mentioned Herbalife by name, and stated that he would not comment on the stock. Unfortunately, not everyone listened. Herbalife stock shot up after Einhorn stated that he would not be commenting about the company.

Oftentimes, we get advice from friends, family, neighbors, etc. It is tempting to hear about a stock that might be the next Apple, but it is foolish to listen to the advice. When it comes to investing, you have to do your own homework. I never give advice to people, and this is one of the reasons.

Einhorn takes this philosophy a step further. He thinks that not only should you not listen to investment advice from amateurs, but even from great investors who have a proven track record. This is a really important statement, which everyone should take to heart.

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I will give one personal example. In the premium section of my website, I give investment ideas to subscribers. I once had a short idea on a Canadian stock. The stock went down about 35 percent in three months, until it was bought out. Later, I learned that Dan Loeb, the famous hedge fund manager, had a large long stake in the company. Had I known this, I likely would have hesitated recommending it as a short.

The lesson for today and for life is, when it comes to investing, do your own homework.