Updated at 4:53 p.m. ET
The dramatic collapse in worldwide demand for oil led to an extraordinary development on Monday: U.S. oil prices fell below zero for the first time ever, and kept falling.
The key U.S. oil benchmark, West Texas Intermediate, settled at negative $37.63.
Driven by a trading contract deadline, traders desperately looked for buyers for the barrels of oil they normally hold in their books. But buyers were hard to find — even when the oil was being given away for free.