Define your risk! If you want to avoid the big loss, then decide how much money you are willing to risk on any given trade. Set a stop on every trade - either an automatic exit, or at least a mental price point at which you will exit the trade. The only time a stop loss is really needed is the time when you really need to stop losing money. The act of setting a stop will stop you from losing more money than you are willing to lose. They aren't foolproof - but they will keep you from proving that you are foolish. There are many critical aspects of stop location. Set a stop, and live to trade another day. These videos should help.