#1 William Gates III

$57.0 billion
Source: Microsoft

#2 Warren Buffett

$50.0 billion
Source: Berkshire Hathaway

#3 Lawrence Ellison

$27.0 billion
Source: Oracle

#4 Jim Walton

$23.4 billion
Source: Wal-Mart

#5 S Robson Walton

$23.3 billion
Source: Wal-Mart

#6 Alice Walton

$23.2 billion
Source: Wal-Mart

#7 Christy Walton & family

$23.2 billion
Source: Wal-Mart inheritance

#8 Michael Bloomberg

$20.0 billion
Source: Bloomberg

#9 Charles Koch

$19.0 billion
Source: manufacturing, energy

#10 David Koch

$19.0 billion
Source: manufacturing, energy

Read rest of the story and view the list of The 400 Richest Americans