The world's youngest billionaires

The world's 20 youngest billionaires are evidence that enormous fortunes can be created in far less than a lifetime. All of them are under 40.

The youngest, Dustin Moskovitz, is just eight days younger than his Facebook cofounder Mark Zuckerberg (both are 26). The oldest in this group, Google cofounder Sergey Brin (age 37), is also the group's richest, boasting a net worth of US$19.8 billion. (For a related reading, see The World's Billionaires 2011)

1. Dustin Moskovitz

Net Worth: US$2.7 billion

The world's youngest billionaire, Dustin Moskovitz, was Mark Zuckerberg's Harvard roommate and Facebook's third employee. He is just eight days younger than his friend. The two dropped out of Harvard and moved to California to work for the social networking firm full time; he was its first chief technology officer and then vice president of engineering. He left in 2008 to start Asana, a software company that allows individuals and small companies to better collaborate. Values of his new company: "pragmatism," "being a mensch," "admitting when you're wrong" and "chill-ness."

2. Mark Zuckerberg

Net Worth: US$13.5 billion

Zuckerberg's Facebook was a key spark in the spread and organisation of the recent revolts in Tunisia, Egypt, Yemen and Libya. Back home President Obama praised Facebook as an example of American innovation in his January State of the Union address. A month later the Facebook cofounder and chief executive sat next to Obama at a dinner with other tech titans, including Apple's Steve Jobs. Over the last year the 26-year-old's fortune surged 238% to US$13.5 billion as investments from firms like Goldman Sachs boosted Facebook's valuation to US$50 billion.

3. Albert von Thurn und Taxis

Net Worth: US$2 billion

First appeared in Forbes' ranks at age 8, but officially inherited fortune in June 2001, on his 18th birthday. Went to high school in Rome; in June 2008 received an M.A. in economics and theology from the University of Edinburgh in Scotland. Assets include real estate, art and a tech company, plus 30,000 hectares of woodland in Germany, one of the largest forest holdings in Europe. Despite local opposition is apparently going ahead with plans to build one of the world's largest solar farms in Bavaria, southern Germany, to sell electricity. Lives in family castle, Schloss Emmeram. (For a related reading, see The Most Expensive Celebrity Real Estate For Sale)

4. Scott Duncan

Net Worth: US$3.1 billion

Son of the late Dan Duncan assumed partial control of his US$12.4 billion pipeline empire after father's death in March 2010 at age 77. Houston's richest man at the time of his death, Dan Duncan grew up poor, starting energy company Enterprise Products with two trucks in 1968. Today it owns more than 49,000 miles of pipelines.

5. Eduardo Saverin

Net Worth: US$1.6 billion

Together with former best bud Mark Zuckerberg, started Facebook at Harvard and received a 30% stake in the company. Relationship soured when Facebook sued Saverin for allegedly interfering with business and insisting on keeping 30% stake; Saverin countersued. The parties settled, with Saverin apparently getting a 5% stake and a cofounder bio on Facebook's site. Source tells Forbes Saverin has been selling shares and now holds 2%. In January made rare news when he led an US$8 million round of financing of Qwiki, a hot Silicon Valley startup.

6. Yang Huiyan

Net Worth: US$4.1 billion

Main shareholder in Country Garden Holdings of Guangzhou, one of China's largest property developers. The company's chairman is Yang's father, Yeung Kwok Keung, who transferred his holding to her before the company went public in Hong Kong in 2007. Wealth is up this year amid strong sales in 2010, owing to the company's large land bank. Yang graduated from Ohio State University with a degree in marketing and logistics. (For a related reading, see Inside The World's First Billion-Dollar Home)

7. Fahd Hariri

Net Worth: US$1.5 billion

Youngest son of slain Lebanese Prime Minister Rafik Hariri inherited stake in his father's construction, telecom and real estate conglomerate Saudi Oger after his death in 2005. Serves on the board of family's Future TV, a satellite and terrestrial television network covering the Middle East. Lives in Paris.

8. Sean Parker

Net Worth: US$1.6 billion

Silicon Valley strategist and former Facebook president debuts as a billionaire based on the surging value the social networking site. His reported stake: just under 3%. At 19 cofounded Napster, music sharing service that brought free music to the masses and helped trigger the record industry's precipitous decline. Made famous after being played by Justin Timberlake in movie The Social Network. Now managing partner at Founders Fund, a venture capital firm that invests in tech companies. Put money into Spotify, popular European music subscription service hoping to launch in the U.S. sometime this year.

9. Ayman Hariri

Net Worth: US$1.5 billion

Son of slain Lebanese Prime Minister Rafik Hariri, who left behind a fortune now shared by his five children. Ayman sits on the board of Saudi Oger, a construction, telecom and real estate conglomerate. Oversees group's construction division, which is behind mega projects such as Princess Noura Bint Abdulrahman University for Women and King Abdullah Financial District. Sits on the board of 3C Telecommunications, a South African mobile operator which is majority-owned by Saudi Oger. (For a related reading, see Multimillionaires Without High School Diplomas)

10. Yoshikazu Tanaka

Net Worth: US$2.2 billion

Founder of Gree, Japan's largest social networking site, may be facing off with Facebook's Mark Zuckerberg soon; setting up shop in California. On global expansion kick - working with Tencent, largest Internet service portal in China. Stock up 35% in past year. Started out at Sony; worked for fellow billionaire Hiroshi Mikitani at online shopping site Rakuten. Left in 2004 to set up Gree at a tech incubator; company name inspired by American social psychologist Stanley Milgram's concept of "six degrees of separation." Transitioned site into mobile gaming to better compete with rivals.

11. Yusaku Maezawa

Net Worth: US$1 billion

Founded online retailer of apparel and accessories; widely popular Zozotown caters to young fashionistas. Website is structured like actual mall where stores are set up; sells on consignment. Sales have grown on average 50% annually over the past five years. Company announced 300-for-1 stock split in December. Maezawa, an avid customer, owns 59% of the firm. Plans to branch out to older customers in alliance with Yahoo Japan. Also looking to sell overseas.

12. Oleg Bakhmatyuk

Net Worth: US$1 billion

Founder and head of egg producer Avangardco joins the billionaires list after floating a 20% stake in the company in June 2010. Stock price up 35% since going public. Sister Nataliya is CEO. Bakhmatyuk previously worked in state oil and gas company Naftogaz Ukraine. (For a related reading, see The World's Most Expensive Divorce Settlements)

13. Andrey Verevskiy

Net Worth: US$1.1 billion

Took agribusiness conglomerate Kernel Holding public on Warsaw stock exchange in 2007. Stock price has doubled over the past year. On acquisition hunt. Parliamentary deputy adroitly switched parties from Yulia Tymoshenko's bloc to new president Victor Yanukovich's bloc when the political winds shifted.

14. John Arnold

Net Worth: US$3.3 billion

The head of hedge fund Centaurus Advisors suffered his first losing year in 2010, rumored to be down 8%. Started trading oil at Enron in 1995; is said to have earned US$750 million for company in 2001. When the energy outfit famously collapsed a year later, he went into business for himself, founding Centaurus, a hedge fund focusing mostly on natural gas and energy trading. Big score: He bought up hedge fund Amaranth Advisors' losing positions in natural gas in 2006.

15. Kostyantin Zhevago

Net Worth: US$2.4 billion

Ukraine's youngest billionaire benefiting from rising iron ore prices; stock in his iron ore producer Ferrexpo doubled over the past year. In the summer rumors swirled of a tie-up with Czech billionaire Zdenek Bakala's NWR, which bought a 21% stake in Ferrexpo in 2008. Company recently purchased Danube River waterway transport provider Helogistics. Graduate of Kyiv State Economic University is also a parliamentary deputy; his party is in opposition to President Yanukovich's Party of Regions. Soccer fan owns FC Vorskla football.

16. Xian Yang

Ne Worth: US$1 billion

Chairman of Hidili Industry International Development, a coke and raw coal mining company. Xian graduated from the People's Police School of Sichuan in 1994, studied law at Southwest University of Political Science and Law, and worked in the police force and customs bureau of Panzhihua in Sichuan Province prior to setting up Hidili in 2000. He was awarded a "Grade Three Achievement" by the Ministry of Public Security for his service. (For a related reading, see Billionaires And Their Toys)

17. Ana Lucia de Mattos Barretto Villela

Net Worth: US$3.2 billion

Low-profile member of one of Brazil's oldest and most distinguished banking families. In 2008 family's Banco Itau merged with Unibanco. Now she is one of the largest individual shareholders of Itau Unibanco Holding SA, Brazil's second biggest bank and one of the world's fifteen largest banks. Brother Alfredo is bank's vice chairman. She serves as president of Alana Institute, a nonprofit organisation created in 1994 with the mission of promoting social work, education and culture.

18. Fang Wei

Net Worth: US$1.3 billion

Beijing-based investor targets underperforming state-owned listed companies for restructuring. Fang took control of a listed company, Fangda Jinhua Chemical Technology, in 2010 after he successfully reorganised Fangda Special Steel Technology, a Shanghai-listed supplier of steel to the auto industry. Fangda Group now has more than 30,000 employees across more than 10 provinces in China. Also invests in minerals.

19. Serra Sabanci

Net Worth: US$1 billion

Board member and shareholder of large conglomerate Sabanci Holding and member of the board of directors of the Sabanci Foundation. Returns to billionaires list this year after falling off in 2009. Her father Ozdemir Sabanci was gunned down in 1996 in his Sabanci Towers office in Istanbul by assassins hired by leftist armed group DHKP-C. She is a niece of fellow billionaire Sevket Sabanci and a cousin of billionaire Suzan Sabanci Dincer.

20. Sergey Brin

Net Worth: US$19.8 billion

Google cofounder Sergey Brin saw company stock rise 18% over the past year as Google maintained nearly two-thirds of the market for online search. Brin focuses on raising margins with Instant Search and building new businesses in communications. Emigrated from Russia at age 6. Son and grandson of mathematicians on his father's side, mother was a research scientist at NASA. Met cofounder Larry Page in computer science Ph.D. program at Stanford and dropped out in 1998 to start Google from a friend's garage. The two share a 767 jet. (For a related reading, see Heirs To Billionaires)