The release of the annual Forbes rich list in March revealed that the fortunes of some of the top 20 billionaires familiar to the art world have taken a hit. Bill Gates (in the number one spot) saw his net worth drop to $75bn from $79.2bn in 2015. Carlos Slim Helu (number four) felt the pain, dropping down to $50bn from $77.1bn. And Larry Ellison (number seven) fell to $43.6bn from $54.3bn. One on the up is Russian tycoon Leonid Mikhelson, whose fortune, made in gas and chemicals, now stands at $14.4bn ($11.7bn last year).