Mark Zuckerberg is now worth a record $47.1bn (£31bn), more than four times richer than the second-richest person in the US under the age of 40.
Zuckerberg, who founded Facebook in 2004 after dropping out of Harvard University took top place on Forbes magazine’s list of the 40 most successful young entrepreneurs in the US after another record year for the social networking website.
More than 1 billion people now use Facebook daily, viewing videos more than 8 billion times.
See list of top 10 billionaires under 40 and their worth:
- Mark Zuckerberg, Facebook, $47.1bn
- Dustin Moskovitz, Facebook, $9.7bn
- Jan Koum, Whatsapp, $8.8bn
- Garrett Camp, Uber, $6bn
- Travis Kalanick, Uber, $6bn
- Elizabeth Holmes, Theranos, $4.5bn
- Nathan Blecharczyk, Airbnb, $3.3bn
- Brian Chesky, Airbnb, $3.3bn
- Joe Gebbia, Airbnb, $3.3bn
- Sean Parker, Facebook, $2.5bn