Bill Ackman has a substantial portion of his hedge fund invested in Amazon and Uber.

Warren Buffett took control of Berkshire Hathaway in 1965 and promptly turned the "doomed" textile mill into a holding company focused on insurance. That decision created a steady stream of investable cash in the form of insurance premiums, and Buffett used that capital to build Berkshire into a trillion-dollar company through savvy acquisitions and stock purchases.

Billionaire Bill Ackman hopes to emulate that success with Howard Hughes . He already owns about 47% of the holding company through his hedge fund, Pershing Square, and plans to use it as an investment vehicle to build a "modern-day Berkshire Hathaway." That is rather ambitious, but Ackman has a good track record. Pershing Square beat the

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