4. Warren Buffett
Estimated net worth: $53.5 46.0 billion
Buffett, 82, is chairman of Omaha-based Berkshire Hathaway Inc. In February, he bought H.J. Heinz Co. for $23.2 billion with Brazilian billionaire Jorge Paulo Lemann. Almost all of Buffetts wealth is held in Berkshire Hathaway, the publicly traded holding company he has run since 1965. He fell one spot since last year, and for the first time since 2000 that he has not been ranked in the top three richest people.