Bill Gates tops this year's Forbes list of the 400 richest Americans with a net worth calculated at $59 billion.
Forbes says the Microsoft co-founder saw his wealth increase by $5 billion from in 2010.
Investor Warren Buffett ranks second with a fortune of $39 billion, though Forbes says the Berkshire Hathaway Inc. chief executive's wealth shrank by $6 billion from a year ago.
Oracle CEO Larry Ellison rounds out the top three with a net worth of $33 billion, a $6 billion increase from 2010.
George Soros entered the top 10 list for the first time at seventh. Forbes estimates his wealth at $22 billion. Three members of the Walton family, descendants of Wal-Mart founder Sam Walton, also are among the top 10 wealthiest in 2011.