New York, Sep 22 (DPA) Microsoft founder Bill Gates still heads Forbes' annual list of the 400 richest Americans, and for the first time in the history of the annual roster all the people on the list issued Thursday were billionaires.

Gates headed the pack with a fortune estimated at $53 billion, followed by investment guru Warren Buffet with $46 billion. Climbing into third place was Las Vegas gambling mogul Sheldon Adelson with some $20 billion. According to the magazine, he has made an average of $1 million an hour since the 'Rich List' was published in 2004.

Oracle founder Larry Ellison was fifth with $19.5 billion, followed by Microsoft co-founder Paul Allen with $16 billion.

Michael Dell and four members of Wal-Mart's Walton family rounded out the top 10.