That still doesn't answer: why wasn't it anticipated and reflected in earlier pricing (even if volume-weighted it would be a much smaller drop, it still seems to have been missed even from futures options)?
In short, the reason nobody anticipated it is because the future is unknown. The reason any market is unpredictable is because there are too many variables to account for.
I'd imagine people just assumed perfect liquidity here, and that they'd be able to sell even "at a small loss which is better than nothing," not realizing that nothing or negative (i.e. you're gonna pay somebody to take this oil off your hands or build your own tanks) is a valid outcome.
too bad the oil market is ... viscous.
Correct me if I'm wrong, but: The people doing the trading are middlemen, and have no capacity period. They expected to be able to sell it all off to the energy companies, even at a loss, so they normally don't accept any physical product. But the energy companies ran out of capacity - something the middlemen (traders) don't have direct knowledge of - so got caught unexpected with contracts they can't sell, and now have to accept the physical product.
US companies don't want to stop producing oil. Couple that with the Russia/Saudi Arabia skuffle going on over oil prices, I'm not surprised. What surprises me is the absolutely rapid/rabid decline in the price. It just seems like pure insanity to me...
Indeed, it looks like the US is reconsidering:
President Donald Trump said Monday the U.S. is "looking to" add as many as 75 million barrels of oil to the Strategic Petroleum Reserve. Trump spoke after an historic day in the oil CL.1, +103.61% markets, in which the May WTI crude contract closed at -$37.63 a barrel, a one-day drop of 306%. Trump said he was considering the move "based on the record low price of oil," and that the action would "top it out." Speaking at a White House press briefing, Trump said, "we'd get it for the right price."
https://www.marketwatch.com/story/trump-says-us-looking-to-a...
Because despite the people that like saying all future events are reflected in current prices, the fact is humans, both individually and aggregated into markets, are imperfectly prescient, thus future events are basically never perfectly priced in to to current market prices.
People say things to the effect of “if it is going to happen, it is already priced in” all the time, on HN even.
> All KNOWN future events are priced in.
There are no such thing as known future events. Market participants estimation of the likelihood of future events, weighted by inclination and capacity to invest, are priced in.