You may even ask your broker about entering on a market order and then manually placing a sell stop limit on one side of the entry and a sell stop limit on the other side of the entry. If that would have made any difference. Which every sell order gets hit the other would be left but maybe the velocity logic event to the downside would not have hurt your position as bad. I don't know. Just have to ask your broker.
That wouldn't have done anything since a stop limit places a limit order at the price you set when that price is traded, however price dropped right through his price level due to the news, so his limit order would have been placed at the requested price, but never be filled.
So, are you saying his limit stoploss would not have been executed? Did price recover after the plunge? With just a regular OCO SL once it is hit price immediately becomes a market order and is subject to queue it is in at that second and if the market was already in a velocity logic would then be rejected because it has become a market order. So, in theory maybe his limit stoploss would not have been executed and he would still have the position on. That is the angle I am looking at but I don't know as I don't use that type of orders in my trading. May have a few times in the past, not sure. I really suspect his order may have been held by the broker and not sent to the exchange until after the velocity logic event was already in place. And why did NT freeze?
We are back well above the level that is stop was, yes. But yes, a stop limit isn't guaranteed to fill and it wouldn't have during that move. However would you really want to take that risk? Leaving that position open with that stop limit who knows how many points away. What if the market kept dropping?
That could happen that is if it kept dropping but if his loss was not executed then would he still have his position on once trading started back? I don't know. Just speculating. I know some recent flash crashes in seconds after they occured the market recovered.
Can you trust any stop loss? (opposite order, platform/broker cut off at X loss...) No. And you had a taste of it on your second week. Some people lost their properties on Swiss bank EUR/CHF cap a few years ago. Freak events are rare but they can wipe you out for more than your investment if you are leveraged. Funny enough they tell us about it in the small prints and we all sign up for it. You can find guaranteed stops at some CFD's brokers, modern bucket shops. In my opinion you were too heavy. 80$ at point with a 2k cut off (probably tighter stop loss) needs very little to happen... The 5min average range of the NQ is more than 2k (with 4 lot)
Ok how does he protect from future slamming of prices by algo's? For that matter can flash crashes be hedged against.