According to America's Forbes magazine, Mexican telecom tycoon Carlos Slim has edged Microsoft chairman Bill Gates out of the top spot of billionaires this year, with a 53.5 billion dollar fortune.
But who are the candidates for the leading postin the future? Here are Forbes' top 10 youngest billionaires.
1. Mark Zuckerberg
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Facebook founder Mark Zuckerberg speaks at the Web 2.0 summit in San Francisco, California, Oct. 17, 2007. Facebook said on Wednesday it will allow members to turn off a controversial feature that monitors the Web sites they visit, and its chief executive apologized for not responding sooner to privacy complaints.(Xinhua Photo)
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Net worth: 4 billion dollars
How: Internet
Age: 25
Citizenship: US
The Facebook-founder launched the social networking site from his Harvard bedroom in 2004.
2. John Arnold

Net worth: 4 billion dollars
How: Energy trading
Age: 36
Citizenship: US
Hired by Enron and founded hedge fund Centaurus Energy in 2002 after Enron collapsed.
3. Yang Huiyan
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| Yang Huiyan. Rank: 277. Her fortune is tied up in her holding in Guangdong developer Country Garden, run by her father Yang Guoqiang, who transferred the shares to her before the firm's 2007 public offering. (Source: chinadaily.com.cn) |
Net worth: 3.4 billion dollars
How: Property
Age: 28
Citizenship: China
Her fortune is tied up in her holding in Guangdong developer Country Garden, run by her father Yeung Kwok Keung.
4. Albert von Thurn und Taxis

Net worth: 2.2 billion dollars
How: Inheritance
Age: 26
Citizenship: Germany
Inherited fortune on his 18th birthday and lives in family castle, Schloss Emmeram.
5. Fahd Hariri

Net worth: 1.4 billion dollars
How: Construction, investments
Age: 29
Citizenship: Lebanon
Youngest son of assassinated Lebanese prime minister Rafiq Hariri inherited stake in his father's construction, telecom and property empire.
6. Aymin Hariri

Net worth: 1.4 billion dollars
How: Construction, investments
Age: 31
Citizenship: Saudi Arabia
The Hariri brothers received a large inheritance from their father, Rafiq Hariri, who rose from a humble start as a construction worker to become prime minister of Lebanon.
7. Yoshikazu Tanaka

Net worth: 1.4 billion dollars
How: Internet
Age: 33
Citizenship: Japan
Like Zuckerberg, Tanaka also made his fortune from a social networking site, Gree.
8. Kostyantin Zhevago

Net worth: 1.2 billion dollars
How: Banking, mining
Age: 36
Citizenship: Ukraine
Has majority stake in iron ore producer Ferrexpo and Finance & Credit Bank.
9. Lee Ziaohui

Net worth: 1 billion dollars
How: Manufacturing
Age: 28
Citizenship: China
Chairman of one of China's biggest private steel manufacturers Shanxi Haixin Iron & Steel Group, since father was shot in 2003.
10. Shahid Balwa

Net worth: 1 billion dollars
How: Property
Age: 36
Citizenship: India
Partner in DB Realty whose projects include Turf Estate, a luxury high-rise, and the 108-storey Park Hyatt Hotel in Mumbai.