No. 1 Bill Gates

Net Worth:$66 billion – As of September 2012
Source of Wealth: Microsoft, self-made , Age: 56 , Citizenship: U.S.


No. 2 Warren Buffett

Net Worth:$46 billion – As of September 2012
Source of Wealth: Berkshire Hathaway, self-made , Age: 82 , Citizenship: U.S.


No. 3 Larry Ellison

Net Worth:$41 billion – As of September 2012
Source of Wealth: Oracle, self-made , Age: 68 , Citizenship: U.S.


No. 4 Charles Koch (tie)

Net Worth:$31 billion – As of September 2012
Source of Wealth: Diversified, inherited and growing , Age: 76, Citizenship: United States


No. 4 David Koch (tie)

Net Worth:$31 billion – As of September 2012
Source of Wealth: Diversified, inherited and growing , Age: 71 , Citizenship: United States


No. 6 Christy Walton & family

Net Worth:$27.9 billion – As of September 2012
Source of Wealth: Walmart, inherited , Age: 57 , Citizenship: U.S.


No. 7 Jim Walton

Net Worth:$26.8 billion – As of September 2012
Source of Wealth: Walmart, inherited , Age: 64 , Citizenship: United States


No. 8 Alice Walton

Net Worth:$26.3 billion – As of March 2012
Source of Wealth: Walmart, inherited , Age: 62 , Citizenship: United States


No. 9 R. Robson Walton

Net Worth:$26.1 billion – As of September 2012
Source of Wealth: Walmart, inherited , Age: 68 , Citizenship: United States


No. 10 Michael Bloomberg

Net Worth:$25 billion – As of September 2012
Source of Wealth: Bloomberg LP, self-made , Age: 70 , Citizenship: U.S.


No. 11 Jeff Bezos

Net Worth:$23.2 billion – As of September 2012
Source of Wealth: Amazon.com, self-made , Age: 48, Citizenship: United States


No. 12 Sheldon Adelson

Net Worth: $20.5 billion – As of September 2012
Source of Wealth: Casinos, self-made , Age: 79 , Citizenship: United States


No. 13 Sergey Brin

Net Worth:$20.3 billion – As of September 2012
Source of Wealth: Google, self-made , Age: 39 , Citizenship: U.S.


No. 13 Larry Page

Net Worth:$20.3 billion – As of September 2012
Source of Wealth: Google, self-made , Age: 39 , Citizenship: U.S.


No. 15 George Soros

Net Worth:$19 billion – As of September 2012
Source of Wealth: Hedge Funds, self-made , Age: 82 , Citizenship: U.S.


No. 16 Forrest Mars, Jr.

Net Worth:$17 billion – As of September 2012
Source of Wealth: Candy , Age: 81, Citizenship: United States


No. 16 Jacqueline Mars

Net Worth:$17 billion – As of September 2012
Source of Wealth: Candy , Age: 72, Citizenship: United States


No. 16 John Mars

Net Worth:$17 billion – As of September 2012
Source of Wealth: Candy , Age: 72 , Citizenship: United States


No. 19 Steve Ballmer

Net Worth:$15.9 billion – As of September 2012
Source of Wealth: Microsoft, self-made, Age: 56 , Citizenship: United States


No. 20 Paul Allen

Net Worth:$15 billion – As of September 2012
Source of Wealth: Microsoft, investments, self-made, Age: 59 , Citizenship: United States