(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.