The World's Youngest Billionaires: 29 Under 40

No. 23: Kostyantin Zhevago
Age: 39
Net Worth: $1.5 billion
Son of a mining engineer, Kostyantin Zhevago took over Poltava Iron Ore, the largest exporter of pellets in CIS, at the age of twenty two, and in 2007 he took his mining company Ferrexpo public. An avid soccer fan, Zhevago owns FC Vorska football.
No 24: Dan Gertler
Age: 39
Net Worth: $2.2 billion
An emerging face of irresponsible capitalism in Africa, Dan Gertler took his family’s fortune in diamonds and invested it in mining assets in the Democratic Republic of Congo. While in his 20s, he became a friend of Joseph Kabila, who then ran the military and is now the DRC’s president.
No. 25: Ana Luia de Mattos Barretto Villela
Age: 39
Net Worth: $1.15 billion
Ana Lucia de Mattos Barretto Villela belongs to one of Brazil’s oldest and most distinguished banking families. She is one of the largest individual shareholders of a holding company that controls Unibanco Holding S.A., one of Brazil’s largest banks.
No. 26: Lee Seo-Hyun
Age: 39
Net Worth: $1 billion
She is the youngest daughter of Samsung Chairman Lee Kun-Hee. A graduate of the Parsons School of Design, she is vice president of the luxury goods and fashion division of Cheil Industries (part of the Samsung Group), as well as a vice president at Cheil Worldwide, Korea’s largest advertising firm.
No. 27: Fang Wei
Age: 39
Net Worth: $1.5 billion
Fang Wei is best known for buying turnaround situations, especially those in the steel industry. Fangda Group now has more than 30,000 employees across more than 10 provinces in China.
No. 28: Sergey Brin
Age: 39
Net Worth: $22.8 billion
The Google cofounder is now director of special projects at the Mountain View, Calif. search giant, leaving his counterpart Larry Page to handle most day-to-day operations. Brin oversees the company’s foray into hardware and futuristic endeavors like driverless cars and augmented reality spectacles known as Google Glass.
No. 29: Larry Page
Age: 39
Net Worth: $23 billion
Google’s cofounder and CEO since April 2011, Page saw the company through the $50 billion revenue milestone in 2012. The stock rose nearly 30% in the past year, adding more than $4 billion to Page’s net worth.
An earlier version of this article incorrectly stated that there are 23 billionaires under 40 years old on the Forbes Billionaires list. It has been updated to reflect the change.