I can recall about four times where an electronic market was swept. Two of those times it took the market some length of time for the order books to populate (if you want to call it that) - and it was super thin and full of gaps. Point being - if he had on 212 cars at one cent, and then the market was swept and the best bid was (-$3.00) and he hits a 10 lot - he's marking down $636K at that point in time... He is going to be paralyzed with fear and disbelief.
I remember the expiring May20 bid/asks being rather thin with low volume that day. A 10 lot is probably the most he could have gotten off at (-$3.00). Panic and despair would have definitely overwhelmed him as he sold them all the way down to -$40.00 Many trading careers have abruptly ended when someone decides to suddenly trade 50 to 100x times their normal size because he thinks he sees something that is too good to be true, and then decides to go for the homerun.
https://www.bloomberg.com/news/arti...s-fined-1-75-million-for-lapses-when-oil-fell Ibkr got a fine. I wonder how much others pay... Ibkr did make anyone whole, hats of to them