The 10 richest Americans

The 10 richest Americans, The 400 richest Americans saw their collective wealth grow by 12% over the past year, meaning the nation's wealthiest slightly outperformed the Standard & Poor's 500 Index ($INX) over the period.

Bill Gates is the nation's richest person for the 18th consecutive year; the last time he didn't rank No. 1 was 1993, when his good friend Warren Buffett eclipsed him. Buffett's fortune tumbled by $6 billion this year, making him the biggest loser among the nation's most wealthy. Buffett gave away $3.3 billion, and he was pinched by a 10% decline in the value of Berkshire Hathaway (BRK.A) stock. gates, buffett, giving pledge,

This year's headlines may belong to a younger group of entrepreneurs marching their way up the ranks, particularly those who are impacting social behavior online. Leading the pack is Facebook co-founder Mark Zuckerberg, who added $10.6 billion to his fortune, making him the year's biggest gainer and pushing him into the top 20 for the first time, with a net worth of $17.5 billion. Zuckerberg came in one notch ahead of Google (GOOG) co-founders Sergey Brin and Larry Page, who added $1.7 billion apiece to their fortunes but slipped five spots in the rankings and are tied at No. 15. Bob Stiller Green Mountain Coffee Roasters, Dan Gilbert Quicken,

Notable newcomers include Bob Stiller of Green Mountain Coffee Roasters (GMCR) and The Go Daddy Group's Bob Parsons. Among those returning to the list this year are Howard Schultz of Starbucks (SBUX) and Dan Gilbert, the chairman and founder of Quicken Loans.

Following is a closer look at the top 10. Go to Forbes.com for the full list of the richest people in America

Bill Gates

Rank: 1
Net worth: $59 billion
Age: 55
Source of wealth: Microsoft (MSFT)
(Microsoft publishes MSN Money)
Residence: Medina, Wash.

Warren Buffett

Rank: 2
Net worth: $39 billion
Age: 81
Source of wealth: Berkshire Hathaway
Residence: Omaha, Neb.

Larry Ellison

Rank: 3
Net worth: $33 billion
Age: 67
Source of wealth: Oracle (ORCL)
Residence: Redwood City, Calif.

Charles Koch

Rank: 4
Net worth: $25 billion
Age: 75
Source of wealth: Koch Industries (manufacturing)
Residence: Wichita, Kan.

David Koch

Rank: 5
Net worth: $25 billion
Age: 71
Source of wealth: Koch Industries
Residence: New York City

Christy Walton

Rank: 6
Net worth: $24.5 billion
Age: 56
Source of wealth: Wal-Mart Stores (WMT)
Residence: Jackson, Wyo.

George Soros

Rank: 7
Net worth: $22 billion
Age: 81
Source of wealth: Hedge funds
Residence: Katonah, N.Y.

Sheldon Adelson

Rank: 8
Net worth: $21.5 billion
Age: 78
Source of wealth: Casinos
Residence: Las Vegas

Jim Walton

Rank: 9
Net worth: $21.1 billion
Age: 63
Source of wealth: Wal-Mart
Residence: Bentonville, Ark.

Alice Walton

Rank: 10
Net worth: $20.9 billion
Age: 61
Source of wealth: Wal-Mart
Residence: Millsap, Texas

Source: money.msn