The richest people got even richer in 2013, adding $524 billion to their collective net worth, according to a ranking of the world’s 300 wealthiest individuals.

The aggregate net worth of the world’s top billionaires stood at $3.7 trillion at the market close Dec. 31, according to the Bloomberg Billionaires Index. The biggest gains came in the technology industry, which soared 28% 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.

Bill Gates, founder and chairman of Microsoft Corp., was the year’s biggest gainer. The tycoon’s fortune increased $15.8 billion to $78.5 billion, according to the index, as shares of Microsoft, the world’s largest software maker, rose 40%.

Gates recaptured the title of world’s richest person May 16 from Mexican investor Carlos Slim. Gates’ fortune has also benefited from a rally in stock holdings that include the Canadian National Railway Co. and sanitizing-products maker Ecolab Inc., which rose 34% and 45%, respectively.


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

Sheldon Adelson, founder of Las Vegas Sands Corp., the world’s largest casino company, was the second-biggest gainer in 2013, adding $14.4 billion to his net worth as the company’s shares rose 71%.

Slim lost $1.4 billion during 2013. His America Movil, the largest mobile-phone operator in the Americas, dropped 12% in the first three months of the year after Mexico’s Congress passed a bill to quash the billionaire’s market dominance. The company finished the year up 2% after a planned expansion into Europe was reined in, reassuring investors who were leery about the billions of dollars in investment the strategy would require.