The actual negative rate in WTI crude futures for May (which close trading next Tuesday) is due to Contango (a specific futures contract phenomenom which I will not get into here).
The thing is that storages are all full and there is a demand shock, so no one was buying anymore to get oil delivered to their location.
It is indeed the first time this has ever happened, but actual WTI spot price today was around $18, not -$37
Stay toasty
