The crash in the price of an oil futures contract expiring Tuesday accelerated Monday, falling through $1 a barrel, all the way to one cent, and then turned negative.

The price of the West Texas Intermediate futures contract for May delivery dropped below $37 a barrel.

Never before has the price of the WTI futures contract traded at negative prices. Last week, the CME Group confirmed the ability of its platform to register negative prices.

The extreme low-level of prices for the May contract is rooted in concerns that facilities for storing oil are reaching maximum capacity.

The most basic explanation for what is happening in the oil market is low demand for fuel. With many Americans working from home, demand for gasoline is very low. Imagine if a gas station could not turn away the next delivery truck, it might slash prices in an effort to clear out its tanks. But if your car’s gas tank is full, you could not take advantage of the low price. Even if were free, you would have no where to put it.

That’s what’s happening across the economy. The gas tanks are full, more supply is coming, and even free oil is not cheap enough.

Still the dive into deep negative territory suggests something even more is at work, perhaps the collapse of a hedge fund or other investment vehicle with a large position in oil futures.

The super-contango aspect of the market is likely contributing to the crash. Super-contango is oil market talk for when the price of oil futures expiring in later months is far above the price of oil futures expiring in the near term. That’s a problem because it means that you are losing a lot of money when you try to sell the contract expiring this week. If you bought that contract with leverage, you may be squeezed and looking to raise cash by selling your position. Even at a negative price, you may be willing to pay someone just to limit your losses. Because once something has gone negative, you know for a fact it can go negative. Zero is not the boundary. Which means it could go even more negative.

The risk-management of broker-dealers and exchanges could exacerbate this. Worried about the ability of investors faced with prices this low, dealers and exchanges could be forcing sales by customers to limit the losses that would follow from a customer like a large hedge fund going belly-up.