The richest person in Asia, Lakshmi Mittal, 60, chief executive officer of the world's largest steelmaker, ArcelorMittal, fell to sixth from fifth as his net worth increased $2.4 billion to $31.1 billion.

The wealthiest Brazilian, Eike Batista, 53, remained at eighth in 2011 as his net worth grew $3 billion to $30 billion. Batista has interests in multiple natural resources companies including Rio de Janiero-based OGX Petroleo & Gas Participacoes SA.

Top Ten

Also on the top-ten list was Amancio Ortega, founder of Inditex SA, the world's largest clothing retailer whose properties include Zara, with $31 billion. Mukesh Ambani, chairman of Mumbai-based Reliance Industries Ltd., fell five spots and $2 billion to ninth, with $27 billion. Christy Walton, of the family that controls Wal-Mart Stores Inc., was 10th with $26.5 billion.

Moscow displaced New York as the city with the greatest number of billionaires with 79, compared with New York's 58. The Asia-Pacific region had more billionaires than Europe for the first time in more than 10 years and gained the most billionaires of any region, with 105 newcomers.

"The billionaires list, while it is a rarified universe, does reflect the enormous changes apparent in the global economy," said Forbes. The "bottom line" for the 2011 list is an increased presence from Brazil, Russia, India and China, particularly among billionaires whose wealth is tied to commodities, he said.

Russia's Richest

Vladimir Lisin, 54, the richest person in Russia, rose to 14th place from 32nd in 2010 as his net worth grew $8.2 billion to $24.0 billion. Lisin owns OAO Novolipetsk Steel, based in Lipetsk, Russia.

Robin Li, 42, the richest person in China excluding Hong Kong, rose to 95th from 258th in 2010 as his net worth grew $5.9 billion to $9.4 billion. Li is the cofounder of social- networking site Baidu Inc. Li Ka-shing, 82, remains the richest person in Hong Kong with $26 billion, up $5 billion from 2010 and was 11th overall. Li's companies have interests in shipping, energy, telecommunications and retail.

Zuckerberg's net worth made the largest percentage gain of any billionaire, more than tripling to $13.5 billion from $4 billion. Palo Alto, Calif.-based Facebook was valued at $50 billion in January by Goldman Sachs.

The Facebook magnate was displaced as the youngest billionaire by Facebook co-founder Dustin Moskovitz, who has $1.4 billion. Others on the list with connections to Facebook include Peter Thiel, Sean Parker, Eduardo Saverin and Yuri Milner.