Forbes estimates Zuckerberg was worth $4 billion in 2010 and is worth $13.5 billion today. Also, according to Forbes, the 2011 Billionaires List breaks two records: total number of listees (1,210) and combined wealth ($4.5 trillion). Read the full story here, and you can read a bio of all 1,210 people on the 2011 Billionaires List here.
Kimberly White / Reuters
Mark Zuckerberg, founder and CEO of Facebook, delivers a keynote address at the company's annual conference in San Francisco, in this file photo taken July 23, 2008. Facebook co-founder and Chief Executive Zuckerberg clocked in at No. 52 with an estimated worth of $13.5 billion, up from 212 and $4 billion in 2010. Six of the founders and investors behind the hot Internet startup made the annual list of world's top billionaires compiled by Forbes and published on Wednesday -- and four of them are new to the roster.