Mexico’s Carlos Slim beat Bill Gates and Warren Buffett for the top spot on Forbes magazine’s annual list of billionaires, becoming the first person from outside the U.S. to lead the rankings in 16 years. The net worth of Slim, 70, who built a telecommunications empire after buying Mexico’s state-run phone monopoly two decades ago, rose $18.5 billion to $53.5 billion. Gates, 54, chairman of Microsoft Corp., fell to second as his net worth increased $13 billion to $53 billion. Buffett, 79, chairman of Berkshire Hathaway Inc., was third with $47 billion, a rise of $10 billion. Slim is the...