Warren Buffett dropped out of the top three for the first time since 2000.
And Facebook’s Mark Zuckerberg saw his ranking drop 31 spots as his net worth declined by $4.2bn.
A record 1,426 people around the world made the US magazine’s latest annual count of billionaires, up 16 per cent from last year. Their average net worth was $3.8bn, rising three per cent from 2012. The total net worth for the list’s billionaires was 5.4 trillion dollars, compared with 4.6 trillion dollars a year ago.
The US continued to be home to the most billionaires in the world, with 442 of them. It was followed by the Asia-Pacific region, with Europe rounding out the top three.
There were 210 new faces on the list, with Forbes saying many were helped by rebounding equity markets and strong consumer brands.
Mr Slim’s net worth increased to $73bn from $69bn a year earlier. Bill Gates of Microsoft held on to second place with a net worth of $67bn.
Mr Buffett slipped to the fourth spot with a $53.5bn net worth. He was surpassed by Spanish clothier Amancio Ortega, who jumped two spots from 2012.