Riches man in the world

Warren Buffett is now the richest man in the world.

Riding the surging price of Berkshire Hathaway (nyse: BRK - news - people ) stock, America's most beloved investor has seen his fortune swell to an estimated $62 billion, up $10 billion from a year ago. That massive pile of scratch puts him ahead of Microsoft (nasdaq: MSFT - news - people ) co-founder Bill Gates, who was the richest man in the world for 13 straight years.

Gates is now worth $58 billion and is ranked third in the world. He is up $2 billion from a year ago, but would have been perhaps as rich--or richer--than Buffett had Microsoft not made an unsolicited bid for Yahoo! (nasdaq: YHOO - news - people ) at the beginning of February.

Microsoft shares fell 15% between Jan. 31, the day before the company announced its bid for the search engine giant, and Feb. 11, the day we locked in stock prices for the 2008 World's Billionaires list. More than half of Gates' fortune is held outside of Microsoft shares.

Mexican telecom tycoon Carlos Slim Helú is the world's second-richest man, with an estimated net worth of $60 billion. His fortune has risen $11 billion since last March.

Buffett, whose fortune is estimated based on his stake in Berkshire Hathaway and assets he holds outside the company, refused to comment on his net worth.

The race for the title of World's Richest Man has been extremely competitive in recent months. Class A shares of Berkshire Hathaway soared 25% between the middle of July and the day we priced our list. The stock hit an all-time high of $150,000 a share in December. At that time, Buffett was worth roughly $65 billion.

Berkshire Hathaway shares closed at $137,100 per share on Tuesday, down 2% since the announcement last Friday that the company's net earnings fell 18% in the fourth quarter of last year.

Gates' fortune also swelled massively last fall. Shares of Microsoft jumped 30% between late October and early November to $37 a share, only to fall after the company announced its intentions to buy Yahoo! for $45 billion on Feb. 1.

Slim's fortune has doubled in the past two years. Stock in his most significant holding, telecom outfit America Movil (nyse: AMX - news - people ), has risen 120% since the beginning of 2006. Helú also owns stakes in Carso Global Telecom, Grupo Carso and Grupo Financiero Inbursa.

The son of a Nebraska politician, Buffett delivered newspapers as a boy. He filed his first tax return at age 13, claiming a $35 deduction for his bicycle. He moved on to study under value investing guru Benjamin Graham at Columbia University.

Buffett began buying shares in textile firm Berkshire Hathaway in 1962 and purchased a controlling stake in 1965. He began buying insurance companies and astutely investing those companies' cash reserves.

Today, Berkshire is invested in insurance (GEICO, General Re), jewelry (Borsheim's), utilities (MidAmerican Energy Holdings (other-otc: MDPWL.PK - news - people )) and food (Dairy Queen, See's Candies). It also has noncontrolling stakes in Anheuser-Busch (nyse: BUD - news - people ), Coca-Cola (nyse: KO - news - people ) and Wells Fargo (nyse: WFC - news - people ). Recently, the company disclosed it owns a significant stake in Kraft Foods (nyse: KFT - news - people ).

In December, the company purchased a 60% stake in the Pritzker family's manufacturing and services group, Marmon Holdings, for $4.5 billion. The privately held Marmon owns businesses across wire and cable, transportation services and industrial products.

Despite Buffett's meteoric rise, his days as the World's Richest Man are almost certainly numbered. He had long promised to give away his fortune posthumously. But in the summer of 2006 he irrevocably earmarked the majority of his Berkshire shares to charity, most going to the Bill & Melinda Gates Foundation.

t the time, the gift was valued at $31 billion. However, assuming that Berkshire shares continue to rise, the final amount of the donation will far exceed that sum. Buffett gives 5% of his shares to charity every July.

In October, Buffett issued a challenge to members of the Forbes 400 richest Americans list, saying he would donate $1 million to charity if the collective group (or a significant number of them) would admit they pay less taxes, as a percentage of income, than their secretaries.

Days after issuing the challenge, Buffett appeared before Congress to encourage it to keep the estate tax. Armed with a few Forbes 400 issues, he told the hearing that "dynastic wealth, the enemy of a meritocracy, is on the rise."