Gates stays on top of rich list

Bill Gates: estimated to be worth $51bn

Microsoft chairman Bill Gates held on to his position as the richest American, according to the latest list of the country's 400 wealthiest citizens compiled by business magazine Forbes.

The publication pegged Gates's assets at $51bn. Microsoft co-founder Paul Allen holds third place with $22.5bn and chief executive Steve Ballmer comes in 11th with $14bn.

Fortunes made in technology dominate the top of the list. Michael Dell's computer and server business has made him $18bn, and Larry Ellison, chief executive of the database and enterprise software juggernaut Oracle, is worth $17bn.

The two Google founders, Sergey Brin and Larry Page, are both valued at $11bn. The surge in Google's stock price last year propelled their net wealth into the double-digit billions.

Also towards the top of the list is Pierre Omidyar, founder of auction website eBay, with a net worth of $10.2bn.

Other well known names include investment guru Warren Buffet (second place with $40bn), several heirs to the Wal-Mart empire (ranked sixth to tenth with more than $15bn each) and three heirs to the Mars food conglomerate (with $10bn each).

The 400 names in the list are worth a collective $1.13 trillion.