(Bloomberg News) Carlos Slim remains the world's richest person for a second year with estimated assets of $74 billion, according to Forbes magazine's annual global ranking of billionaires.

The net worth of Mexico's Slim, 71, whose holdings include the largest mobile phone operator in the Americas, rose $20.5 billion. Bill Gates, 55, chairman of Redmond, Wash.-based Microsoft Corp., was second again as his net worth rose $3 billion to $56 billion. Warren Buffett, 80, chief executive officer of Omaha, Neb.-based Berkshire Hathaway Inc., held on to third place with $50 billion.

"It wasn't even close this year," said Forbes Media Editor-in-Chief Steve Forbes. Slim's net worth gained the most of any billionaire compared with 2010, Forbes said.

Mark Zuckerberg, the 26-year-old co-founder and chief executive officer of social-networking website Facebook Inc. jumped to 52nd this year from 212th place last year. There were a record number of billionaires in 2011, with 1,210 total, compared with the previous high of 1,125 in 2008, and there were 214 newcomers in 2011, with 54 from China and 31 from Russia.

Slim's America Movil SAB is the biggest mobile-phone company in the Americas, with 225 million wireless subscribers. The company also controls Mexico's largest landline phone carrier, Telefonos de Mexico SAB, and the largest TV and long- distance operators in Brazil, as well as phone and video carriers in Colombia, Peru and other South American countries.

Slim's Holdings

His holdings in Mexico extend from retail, with the Sanborns department store chain, to banking and construction. He holds stakes in U.S. companies including the New York Times Co., Saks Inc. and Bronco Drilling Co. Slim's gains in 2010 included his bank Grupo Financiero Inbursa SAB, which surged 42% as it expanded its branches, and Grupo Carso SAB, which almost doubled as it prepared for spinoffs of its mining and real- estate units.

Gates founded Microsoft in 1975 after dropping out of Harvard University and since then the company has become the world's largest software maker. Gates' holdings include about 581 million shares of Microsoft Corp., according to filings with the Securities and Exchange Commission. The stock lost 0.5% during the past year as of Feb. 14, the date the rankings are based on.

Buffett holds about $45 billion, or about 90% of his net worth, in Berkshire Hathaway A shares, which gained 12% over the past year through Feb. 14. Buffett has taken a salary of $100,000 for each of the last 30 years, according to a spokeswoman.

Reliable Numbers

Forbes doesn't disclose the exact methodology of its rankings, which are based on publicly disclosed holdings in addition to privately obtained information, and consider financial assets, real estate and collectibles. The list was based on the value of holdings as of the close of U.S. markets on Feb. 14.

"We often get asked how reliable are our numbers," said Luisa Kroll, senior editor for Forbes. "It's our job to figure out who are the people that are trying to pump up their numbers and who are the people that are trying to hide their numbers."

Of the 1,210 billionaires on this year's list, 648 saw their net worth increase and 160 saw their net worth decrease. There were 214 newcomers to the list in 2011, including Mark Pincus, founder of San Francisco-based Zynga Game Networks Inc., creator of FarmVille.

The $4.5 trillion held by billionaires on the Forbes list represents about 2.3% of the world's wealth. The Credit Suisse Research Institute, based in Zurich, estimated the world's households had about $195 trillion in assets last year.

U.S. Dominates

No one region dominated the rankings. The U.S. had the greatest representation, with 34%, followed by the Asia- Pacific region with 27%.

"This year, the United States is still number one but the lead is shrinking," said Forbes. Ten years ago U.S. residents accounted for about 50% of the list, he said. "The trend is very real."

The Standard & Poor's 500 Index returned 15% in 2010, compared with a 1.9% loss for the Euro Stoxx 50. India's Sensex Index returned 19% for the year and Hong Kong's Hang Seng Index gained 8.6%.

Arnault's Wealth

The wealthiest European, Bernard Arnault, 62, chairman and chief executive of LVMH Moet Hennessy Louis Vuitton SA, the world's largest maker of luxury goods, jumped to fourth from seventh as his net worth increased $13.5 billion to $41.0 billion. LVMH announced Monday it will acquire a controlling stake in Bulgari SpA, the world's third-largest jeweler.

Larry Ellison, 66, chief executive officer of Oracle, Corp., rose to fifth this year from sixth in 2010. Ellison's net worth increased $11.5 billion to $39.5 billion as shares of his firm returned 43% as of Feb. 14. Redwood City, Calif.-based Oracle Corp. is the world's second-largest software maker.

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.

New York City Mayor Michael Bloomberg, 69, fell to 30th from 23rd with $18.1 billion. The mayor is founder and majority owner of Bloomberg News parent Bloomberg LP.

Japan was notable for its relatively small presence on the list compared with the size of its economy, said Forbes.

"Twenty years ago Japan was said to take over the world. Today it is not even holding its own," said Forbes. "So things do change."