TheStreet. Warren Buffett is arguably the most successful investor of all time. He's amassed an amazingly massive net worth by buying and usually holding stocks for the long haul. Trained under legendary value fund investor Benjamin Graham,

Shares of UnitedHealth Group surged nearly 14% on Friday after billionaire Warren Buffett's Berkshire Hathaway bought 5 million shares of the company, providing a shot in the arm for investors who think the health conglomerate will turn around under its new CEO.

If any investor has stood the test of time, it is Warren Buffett, and with good reason. For years, the “Oracle of Omaha” has had a rock-star-like presence in the investing world, and his annual Berkshire Hathaway shareholders meeting draws thousands of loyal fans who are investors.