America's Youngest Billionaires-co-founded facebook

Only eight American billionaires are under the age of 40, and three of them co-founded Facebook.

The youngest? It isn't who you think it is. The world's youngest billionaire is now 26-year-old Dustin Moskovitz, who is eight days younger than his former Harvard roommate and Facebook co-founder Mark Zuckerberg. The social-networking site's first chief technology officer, Moskovitz left in 2008 and started Asana, a software company that allows individuals and small companies to better collaborate. The company has attracted several of the same early backers as Facebook and may one day be worth something. For now, though, Forbes estimates Moskovitz's entire $1.4 billion fortune comes from his 6 percent stake in Facebook.
Zuckerberg may no longer reign as the youngest member of the Forbes 400, but he has bragging rights as the year's biggest percentage gainer -- his net worth jumped to $6.9 billion, up from $2 billion, making him worth nearly five times as much as Moskovitz and more than even Apple's (Nasdaq: AAPL - News) Steve Jobs.

I bet they definitely didn't think that they would reach here. Obviously their devotion, Hard Working and the above all some introduced new ideas in the market, that is why they are here in the list now. Hats off to all these youngsters