Billionaires worth $3.7 trillion surge as Gates wins 2013

The rich keep getting richer. The old adage was never more true than in 2013, when the world's billionaires added $524 billion to their collective net worth, topping the group out at $3.7 trillion.

According to the Bloomberg Billionaires Index, the biggest gains came in the technology industry, which soared 28 percent during the year. Of the 300 people who appeared on the final ranking of 2013, only 70 registered a net loss for the 12-month period.

Regaining his spot as richest man in the world, Bloomberg reports Bill Gates, the 58-year-old founder of Redmond, Wash.-based Microsoft Corp. (Nasdaq: MSFT), increased his fortune by $15.8 billion to $78.5 billion.

Less than a quarter of Gates’s fortune is held in Microsoft, with the majority held in Cascade Investment LLC, an entity through which he owns stakes in about three dozen publicly traded companies and several closely held businesses, including Four Seasons Hotels and Resorts and Corbis Corp., a photo-archive company. He’s also donated $28 billion to the Bill & Melinda Gates Foundation.

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