"Oil that is scheduled to be delivered in June fell 12 percent Monday to about $22 a barrel, but at the same time a benchmark to be delivered next month was essentially deemed worthless."

"Owing largely to a quirk in the way that oil prices are set, the May benchmark actually fell into negative territory, suggesting people who had oil to sell were willing to pay to have it taken off their hands. The problem is that the United States is running out of places to store its oil, which is already being stockpiled on barges at sea and in any nook and cranny companies can find in their facilities. Traders are now worrying that even this space is running out. Under futures contracts, West Texas Intermediate — the American benchmark for oil prices — is delivered to Cushing, Okla., but investors are worried that there will be no place there to put it."

The NYT reports.