Facebook CEO Mark Zuckerberg and other Silicon Valley leaders have formally launched a political group aimed at revamping immigration policy, boosting education and encouraging investment in scientific research.

The net worth of the richest Americans grew by 13% in the past year to $1.7 trillion (€1.3tn), Forbes magazine said, and a familiar cast populated the top of the annual list, including Bill Gates, Warren Buffett, Larry Ellison and the Koch brothers.

THE global ranks of billionaires grew by 199 people in the past year, but none came close to unseating Carlos Slim, the world’s richest man, who added $20.5 billion (€14.83bn) to his coffers, according to Forbes magazine’s annual tally.