Full list
1. Bill Gates – $59 billion
2. Warren Buffett – $39 billion
3.Larry Ellison – $33 billion
4. (Tied) Charles Koch and David Koch, $25 billion each
5. Christy Walton & family – $24.5 billion
6. Christy Walton & family – $24.5 billion
7,  George Soros – $22 billion
8. Sheldon Adelson – $21.5 billion
9. Jim Walton – $21.1 billion
10. Alice Walton – $20.9 billion
11.S. Robson Walton – $20.5 billion
12. Michael Bloomberg – $19.5 billion
13.Jeff Bezos – $19.1 billion
14.Mark Zuckerberg – $17.5 billion
15. (Tied) Sergey Brin and Larry Page – $16. billion each
17. John Paulson – $15.5 billion
18. Michael Dell – $15 billion
19. Steve Ballmer – $13.9 billion
20. (Tied) The Mars family (Forrest, Jacqueline, and John Mars) – $13.8 billion each

http://www./2011/09/facebooks-mark-zuckerberg-joins-top-20.html#ixzz1Yh3mhyyr