Top 10 Tech Billionaires
Mark Zuckerberg: Zuckerberg is a co-founder and the chief executive of Facebook, the world's largest social media site. Launched in 2004, the site has 845 million monthly active users-about 12 per cent of the world's population.
The company is poised for a public offering in the spring, an event that will likely add billions to Zuckerberg's net worth.
Estimated net worth: $21 billion