Billionaires' club: Mark Zuckerberg becomes sixth-richest person on Earth

The 31-year-old also overtook the Koch brothers to become the fourth-richest in the US, as Facebook's record fourth-quarter profits bring net worth to $47.5bn

Facebook CEO Mark Zuckerberg is now the sixth-richest person on Earth and the fourth-richest person in US, his net worth surpassing that of the politically influential Koch brothers, according to the Bloomberg Billionaires Index.

Facebook reported a quarter of record revenue, with sales up 52% and net income more than doubling since last year. Zuckerberg's wealth rose by $6bn on Thursday, taking his net worth to $47.5bn.