Oil prices plunged on Monday as traders got caught in a desperate race to offload contracts for just about any price they could get.

The price of a contract to deliver West Texas Intermediate crude oil next month plunged below zero, as traders got caught in flurry to sell their contracts before having to actually receive the oil.

The oil price is determined through investments known as futures contracts, which are agreements to buy and sell a certain amount of oil at a certain time in the future. The contract to deliver oil in May has been the most commonly traded contract of late, so it is currently considered to be the best proxy for the current oil price. Soon June's contract will be the benchmark.
https://www.cbc.ca/news/business/oil-price-monday-1.5538048