[tialaramex]

And as you'd expect ETF managers "fixed" this by shuffling things so that the "same" ETF is now backed by a different mix of futures they're less worried about.

My opinion is that ETFs are legalised bucket shops and ought to go away. The Oil Futures market represents an actual need, Alice wants to sell her oil knowing what she'll get for it when it's delivered in a week's time, Bob wants to be able to lock in today's prices for next week's oil. There is clearly a deal to be made there and if people who don't actually need oil want to tie themselves up in it and maybe improve liquidity I guess I won't stop them. But Oil ETFs are just a way to gamble on the value of the Oil Futures, and that's why we forbade bucket shops. Negative future prices show that the mechanisms which are supposed to make ETFs safer than bucket shops are flawed, and IMO too flawed to continue to accept them as a legitimate business.