Because of oversupply, storage tanks for WTI are becoming so full it is difficult to find space. The US Energy Information Administration said last week that storage at Cushing, Oklahoma, the heart of the US pipeline network, was about 72% full as of April 10, the Reuters reported.
"There's no available storage anymore so the price of the commodity is effectively worthless," said Bob Yawger, director of futures at Mizuho in New York. "So when it's minus a dollar, they'll pay you a dollar to get it out of there."
The price plunge was partly due to the way oil is traded. A futures contract is for 1,000 barrels of crude, delivered into Cushing, where energy companies own storage tanks with roughly 76 million barrels of capacity.