Bill Ackman is one of the most widely followed investment managers in the world. He's in charge of Pershing Square Capital, a hedge fund focused on investing in just a handful of Ackman's best ideas. His highly concentrated portfolio is full of great companies, but he might have just made one stock the biggest holding at Pershing Square.

Go big or go home. Billionaire investor Bill Ackman of Pershing Square Capital Management takes that sentiment to heart. His hedge fund has some $13 billion in assets under management, but he owns just 10 stocks (track his portfolio here),

Billionaire Bill Ackman has made huge bets in favour of Uber, specifically predicting huge growth potential in ride-sharing, food delivery, and newer markets like advertising and autonomous vehicles.

Bill Ackman built a net worth of $9.3 billion by spotting promising opportunities. Ackman noted in his post on X (formerly known as Twitter) that his hedge fund has owned Federal National Mortgage Association (OTC: FNMA) (commonly known as Fannie Mae) for more than 10 years.