@tester89 > I don’t really understand why the traders would end up owing money. If they thought they were paying 0,01 $/bbl but we’re actually “paying” -37 $/bbl wouldn’t IB owe them?

My thoughts precicely, is there anyone on here that could explain the intricacies of these kind of trades?

He sold it (or IB did so on his behalf at end of day) at -$37.

i understood that he bought at -3.7, and then it dropped further to -37.