The World's Youngest Billionaires: 29 Under 40

Jack Dorsey

No. 8: Marie Besnier Beauvalot
Age: 32
Net Worth: $1.5 billion
Marie, along with siblings Emmanuel, 42, and Jean-Michel, 45, inherited French dairy giant Lactalis, producers of popular Président brie among hundreds of other cheese, milk and yogurt brands.
No. 9: Sean Parker
Age: 33
Net Worth: $2 billion
Parker is revamping his much hyped start-up, Airtime, with the hopes that the video chat site will have the impact of his other Web companies. At 19, Parker skipped college to disrupt the recording industry with music swapping site Napster. He served as Facebook’s first president at age 24.
No. 10: Ayman Hariri
Age: 34
Net Worth: $1.35 billion
Hariri is the son of slain Lebanese Prime Minister Rafik Hariri. He’s involved in running Saudi Oger, one of Saudi Arabia’s biggest construction companies, and the source of the Hariri family fortune.
No. 11: Yvonne Bauer
Age: 35
Net Worth: $2.4 billion
Bauer owns 85% of her family’s publishing empire. She is the fifth generation of the family to run the Bauer Media Group, which was founded in 1875. It publishes 570 magazines in 16 countries.
No. 12: Yoshikazu Tanaka
Age: 36
Net Worth: $1.8 billion
Founder and CEO of social-network game site operator Gree, Tanaka has faced stiff competition this year from archrival DeNA and a game initiative by NTT DoCoMo, the giant cellphone carrier. To get back on track, Tanaka moved to partner with Yahoo Japan and went on a buying spree.
No. 13: Maxim Nogotkov
Age: 36
Net Worth: $1.3 billion
Nogotkov got his start selling computer programs while in school and later began selling cordless phones. He dropped out of college in order to have more time to focus on building his business. He later founded cell phone retailer Svyaznoy.
No. 14: Alejandro Santo Domingo Davila
Age: 36
Net Worth: $11.7 billion
A Harvard history grad, Domingo Davila is the eldest son from his jet-setting beer magnate father’s second marriage. Now a managing director at a New York-based investment advisory firm, Alejandro sits on the board of the Metropolitan Museum of Art in New York.
No. 15: Jack Dorsey
Age: 36
Net Worth: $1.1 billion
Dorsey made a name for himself as a cofounder and leader of 140-character microblogging company Twitter, but most of his fortune is derived from his stake in mobile payment company Square. The New York University dropout is a certified masseur known for his eclectic interests, which include, among other things, punk music and clothes.