A leading U.S. financial magazine has released its annual list of the 400 richest Americans - topped by a familiar name, Microsoft founder Bill Gates.

Gates leads the Forbes list for the 14th year in a row, with a fortune of $59 billion. Investor Warren Buffet, who pledges money to Gates' charity foundation, follows close behind with $52 billion.

To qualify for this year's list, members had to be worth a minimum of $1.3 billion, which is 300 million more than it took to make the list last year.

The youngest member, 33-year-old John Arnold, made $1.5 billion managing large hedge fund investments. The oldest billionaire, John Simpot -- 98 years old and worth 3.5 billion -- made his fortune in the potato business.

According to Forbes, nearly half of the new members made their fortunes in financial markets. The rest of the list includes a number of oil tycoons, casino moguls and the heads of technology companies.

Some information for this report was provided by AFP and Reuters.