Newer figures in technology advanced quickly - including Mark Zuckerberg

Facebook founder and CEO was ranked number 10 with $34billion fortune

Top 400 were largely the same people thanks to buoyant stock market 

America's wealthiest are worth more than ever - with the top 400 billionaires worth a breataking $2.3trillion, according to the latest edition of the Forbes 400.

The renowned rich list was again topped by Bill Gates - the richest American for the past 21 years - whose fortune was $81.2billion. 

But the Microsoft founder, 58, had newer technology billionaires snapping at his heels, including Facebook CEO Mark Zuckerberg, who broke the top 10 for the first time having gained $15billion in the past year.