Here's the Billionaire Investor You Should Be Following -- and He's Not Warren Buffett or Bill Ackman

It's always a good idea for individual investors to look at what institutional investors, also called the smart money, are choosing. You should never base your decisions solely on others without doing research, but institutional investors have been professionally trained, and they often have decades of experience and the returns to back it up.

Following these successful investors is also a good way to find new ideas and check your thesis. Still, too often, I feel like individuals are only looking at two or three of the best investors instead of casting a wider net.

Warren Buffett and Bill Ackman certainly come to mind. I have nothing against Buffett or Ackman, who are certainly two of the best ever, but here's the billionaire I think people should be following.

A strong record despite fundamental shifts

David Einhorn manages hedge fund Greenlight Capital, which he launched at the age of 27 after raising about $900,000 from family and friends. Einhorn rose to prominence from betting against -- or short-selling -- Allied Capital in 2002 when he questioned the company's accounting practices.

Years after he announced his short position, the Securities and Exchange Commission validated Einhorn's thesis, finding that Allied did indeed break securities laws due to its accounting practices.

Einhorn also played a key role during the Great Recession when he shorted Lehman Brothers in 2007 due to the company's underwater securities holdings.

But like many of the greats, Einhorn also is known for his value investing approach, in which he looks for stocks trading below their intrinsic value. Earlier this year, he said that he believes the practice of value investing might be dead due to the broken market structure and the rise of passive investing:

Value is just not a consideration for most investment money that's out there. There's all the machine money and algorithmic money, which doesn't have an opinion about value, it has an opinion about price: "What is the price going to be in 15 minutes, and I want to be ahead of that."

This shift in market structure has led him to change his investing philosophy for his larger company holdings. Now, he focuses on companies that look cheap in value and return capital to shareholders through repurchases or dividends. It's always a good sign to see even the best investors adapt, even though Einhorn is probably frustrated by this shift in market structure.

Despite changing his strategy, he has generated strong long-term returns. Greenlight has average annual returns of 13.1% since its launch in 1996, compared to 9.5% for the broader benchmark S&P 500. That equates to a total return of over 2,900% compared to the S&P 500's 1,117%.