For individual investors, it can pay to follow what the professionals are doing. Specifically, if you are a buy-and-hold investor you can find ideas from like-minded investing legends. One investor to follow closely is Bill Ackman of Pershing Square Capital Management. The billionaire investor runs a $10 billion portfolio for outside investors, owning positions in just seven stocks that he and the team have held for many years. Ackman's second-largest position is Chipotle Mexican Grill (NYSE: CMG).