People have to use the mechanisms that work for their style of trading.  Many could have been spared the big drops in McFaulds stocks with stop-loss orders.  If one doesn't have the time to babysit a stock all day watching price changes, then a stop is a sensible idea.  One has to keep in mind the volatility ranges and stay outside of them if one doesn't want to constantly be triggered.  Setting a stop has the added advantage of taking the emotion out of the equation from a previous trading decision made in a calm moment.  If you don't want to see your profit diminish below a particular percent then you can set it and continue with your regular work routine with some degree of safety.  If you are around to watch, it is also  possible for you to buy back in at a lower sp rather than holding and watching it go down as most seem to do.  If most people were to track their trading history, they would have to admit that they followed the sp down when they could have gone to cash and a stop loss would have done wonders for them when they didn't have the discipline to do it themselves in the heat of the moment.