Los Angeles: America's economic woes don't appear to be hurting philanthropist Bill Gates, who tops Forbes' list of the 400 richest Americans for the 18th year in a row.

The magazine said on Wednesday that the wealth of Microsoft co-founder amounts to $59 billion (Dh216.68 billion), ranking him ahead of all the other billionaires who make up this year's list.

Gates' fortune swelled by $5 billion from a year ago, outpacing the No 2 on the list, Warren Buffett, whose net worth is $39 billion, Forbes said.

Buffett, who wrote in a recent piece for The New York Times that the tax rate he paid last year was lower than that paid by any of the other 20 people working for him in his office, was the only person among the top 20 on Forbes' list to see his fortune shrink from a year ago.

The Berkshire Hathaway chairman and CEO's fortune decreased by $6 billion — the largest dollar-amount loss by anyone on the Forbes 400 this year, the magazine said.

Soros breaks into top ten

Oracle CEO Larry Ellison rounds out the top three richest Americans with a net worth of $33 billion, $6 billion more than last year.

Financier George Soros took seventh place, his first time among the top ten. Forbes estimates his wealth at $22 billion. Soros' net worth is thanks to investments in gold and related securities as well as equities. Soros switched to cash in the spring, allowing him to preserve his gains and miss market turmoil caused by the sovereign debt crisis in Europe.

This summer, Soros announced he would close his hedge fund and give money back to outside investors, focusing on managing investments for himself and his family instead.

Forbes said hedge funds are notoriously secretive and that after he shut his fund, Soros shared more information with the magazine about his wealth. "We always thought we were low on our estimates of him, but this time we had more details bringing him to No 7," said Forbes senior wealth editor Luisa Kroll.

Waltons on list

Meanwhile, three members of the Walton family, descendants of Wal-Mart Stores founder Sam Walton, also are among the top 10 wealthiest Americans this year. Rounding out the top ten are Sheldon Adelson, CEO of casino developer and operator Las Vegas Sands, and the oil billionaire brothers Charles and David Koch.

Forbes said the combined wealth of the 400 people on this year's list is $1.5 trillion, with an average net worth of $3.8 billion. That amounts to a 12 per cent increase from last year.

Some 262 people on the list saw their fortunes grow, while 72 saw a decline, the magazine said.

This year, entrepreneurs dominate the list at an all-time high of 70 per cent, Forbes said.

All told, 18 people made it to the Forbes 400 for the first time this year.

Facebook founder Mark Zuckerberg was the biggest dollar gainer on the list, with a net worth of $17.5 billion that earned him the No 14 spot. There were 42 women on the list, including media mogul Oprah Winfrey at No 139.

Rich list

  • Bill Gates, $59 billion
  • Warren Buffett, $39 billion
  • Larry Ellison, $33 billion
  • Charles Koch, $25 billion and David Koch, $25 billion. (TIE)
  • Christy Walton and family, $24.5 billion
  • George Soros, $22 billion
  • Sheldon Adelson, $21.5 billion
  • Jim Walton, $21.1 billion
  • Alice Walton, $20.9 billion.