Were there any known high-frequency firms suffer from it?
As the brent price stays normal, I believe that many algorithms would have recognize that price different as an arbitrage opportunity.
For a simple example, the brent price and WTI price almost never differ more than 50%, but now WTI price is 10 while the brent price is 20. The algorithms will start buying WTI but the price of WTI soon drop around 0, margin-calling all these algorithmic traders.
My question is, was the WTI price actually down to zero on Apr 20? Was it just a pricing mistake on some platforms?
Price chart: investing.com/commodities/crude-oil-candlestick