The surging price of Microsoft shares returned US tech tycoon Bill Gates back to the top of Forbes's world's billionaires list, with his $76 billion beating out Mexico's Carlos Slim's $72 billion. The annual list, released Monday, counted 1,645 men and women as billionaires, with an average wealth of $4.5 billion and a collective wealth of $6.4 trillion, up $1 trillion from a year ago.
Gates, co-founder of the US software firm, showed his staying power at the top - the world's richest man for 15 of the past 20 years, according to Forbes - despite spending recent years giving away large sums of money to global health and anti-poverty programs.
Gates owns about 4.4 percent of Microsoft, making up less than 20 percent of his total fortune. But the company's share price has risen 25 percent over the past year, and, along with gains in other assets, he has added $7 billion to his fortune since a year ago, according to Forbes. Slim, with a hand in everything from telecommunications (America Movil) to mining, finance and industry (Grupo Carso), to retailing and real estate across the Americas region, was worth $1 billion less than a year ago, hit in part by sagging markets in South America.