Pablo Picasso's La Gommeuse was auctioned at Sotheby's as part of the collection of a businessman estimated to have a net worth of how much?
La Gommeuse:  It was offered for sale "ex" the William I. Koch collection at a Sotheby's, New York, auction on 5 November 2015. Bill Koch (businessman): Forbes" estimated Koch's net worth at $4 billion in 2012 from oil and other investments.
$4 billion