New York -- US tycoons are back on top with Microsoft founder Bill Gates again the world's richest man in a year when even billionaires felt the heat of the global recession, Forbes magazine said Wednesday.

The wealthy few did not escape big shocks this year, with net worth on the list of 793 billionaires -- down from 1,125 billionaires in 2008 -- plummeting to 2.4 trillion dollars from 4.4 trillion, Forbes said.

"The biggest news today is that we are here and there still are billionaires," Forbes spokeswoman Monie Begley joked at a press conference.

The much-watched annual rich list put Gates back on top with a net worth of 40 billion dollars, although he saw his bank balance lose 18 billion over the last 12 months.

Investor Warren Buffett came in second, with 37 billion dollars, despite losing 25 billion dollars this year in the value of his Berkshire Hathaway shares.

Also losing 25 billion dollars was Mexican telecoms king Carlos Slim. However, Slim still managed to come in third with 35 billion dollars.

The surge of American billionaires sent billionaires from India, Russia and Turkey into retreat.

Americans filled 10 of the 20 top spots and New York replaced Moscow as home to most billionaires, with 55 to 27. London comes in second with 28.

Russia, where wealth is closely tied to commodity prices, lost almost two thirds of its billionaires, down from 87 to 32.

Russian oligarchs have long been famous for flaunting their wealth, but this year, none of them make it into the elite top 20. In 2008, there were four Russians in the top 20.

India lost more than half of its billionaires, with the total going from 53 to 24.

Two Indians appear in the top 20, notably steel magnate Lakshmi Mittal with just 19.3 billion dollars after losing 25.7 billion dollars over the last year.

New York Mayor Michael Bloomberg, at number 17, was notable as the only top 20 member to see a net gain.

That was not because of his salary, which is a symbolic one dollar a year, but thanks to re-evaluation of Bloomberg financial news agency after the mayor bought a 20 percent stake from Merrill Lynch last year for 4.5 billion dollars.

About 64 percent of the billionaires are self-made and their average age is 63.7, a slight rise resulting from the lower number of rich Russians and Chinese, whose average ages last year were 46 and 48.

By contrast with that aging trend, Gates is a relatively youthful 53.

The youngest billionaire prize this year goes to Albert von Thurn und Taxis of Germany, who is 25 and listed as having 2.1 billion dollars.

But one of the young success stories from last year -- Facebook founder Mark Zuckerberg -- dropped off the list altogether.

The top concentrations of billionaires in the United States are in California, then New York and Texas.

One billionaire unlikely to welcome the attention though is Joaquin Guzman Loera, 54, whose one billion dollars is derived from cocaine trafficking.