Having traded through the flash crash in 2010, the problem was getting your stop filled. If you are in an active day trade with a reasonably close stop, it's ok. You might slip a bit but the carnage then happens after. The problem is when you have limits set well below and they trigger, then slip, then your stop gets triggered moments later but you still haven't been filled for either. Usually, the brokers systems are all over the place at this point in terms of comms delays, database delays, etc. That's when it gets a bit gnarly. A lot more controls were put in since then but still...
Either that or jump off nearest tall building. Glad I didn't have to concern myself with it back then (I was flat) or whether such a thing as luck exists then or now. As for big boys (banks/corps) a momentary blip.
This concept of guaranteed stop is new to me. I checked into it now and found a page from a company called IG and they said they only charge you for fee if it gets executed. Is this company legit?
So it's not like, I want to buy YM at 10,000 and I buy a guard at 9500 or something so even if price drops to 2000 I still get filled at 9500?