1. Mark Zuckerberg: $71 billion
Age: 33
Source of wealth: Facebook
Forbes 400 rank: 4
2. Dustin Moskovitz: $13.6 billion
Age: 33
Source of wealth: Facebook
Forbes 400 rank: 32
3. Lukas Walton: $13.2 billion
Age: 31
Source of wealth: Inherited, Walmart
Forbes 400 rank: 33
4. Scott Duncan: $5.5 billion
Age: 34
Source of wealth: Inherited, Pipeline company Enterprise Products Partners
Forbes 400 rank: 97
5 (TIE). Nathan Blecharczyk: $3.8 billion
Age: 34
Source of wealth: Airbnb
Forbes 400 rank: 186
5 (TIE). Brian Chesky: $3.8 billion
Age: 36
Source of wealth: Airbnb
Forbes 400 rank: 186
5 (TIE). Joe Gebbia: $3.8 billion
Age: 36
Source of wealth: Airbnb
Forbes 400 rank: 186
8. Rishi Shah: $3.6 billion
Age: 31
Source of wealth: Healthcare media company Outcome Health
Forbes 400 rank: 206
9 (TIE). Bobby Murphy: $3.1 billion
Age: 29
Source of wealth: Snapchat
Forbes 400 rank: 248
9 (TIE). Evan Spiegel: $3.1 billion
Age: 27
Source of wealth: Snapchat
Forbes 400 rank: 248
10. Julio Mario Santo Domingo III: $2.4 billion
Age: 32
Source of wealth: Inherited, Anheuser-Busch InBev
Forbes 400 rank: 340
Source: Business Insider India