Yep so a stop order is usually a pending market order that only triggers once that price trades. Market psychology dictates that some prices are very likely to have a lot of stop orders waiting there, often much larger size than can be absorbed by the limit orders on the other side, this is why the price shoots up or down very quickly when the number of market orders outweighs the limit orders on the opposite side. ====> PLEASE IGNORE THE NOTES. I'm lazy when I have to write messes up in my brain.