Forbes magazine estimated this week that Nets owner Mikhail Prokhorov lost between $5 and $6 billion last year, placing his net worth between $13 billion and $12 billion, down from $18 billion last March.
Most of that loss has come from the poor performance of his public holdings, which have gotten battered along with the Russian stock market.
Prokhorov still has an estimated cash pile of $4 billion, proceeds remaining from his 2008 sale of Norilsk Nickel to fellow billionaire Oleg Deripaska.