This is a problem that is a lot more complex than it appears. There is a delicate balance tween closing a position early ,to break even or take a loss, recognising when you have been wrong to take the trade, and panicing out. Any idiot can take a position and let it ride way against or way in the money. You are supposed to reevaluate the position based on market conditions, not your p&l. This is a lot harder to do in real time than is admitted by most. You may want to double up if it moves against you , on the principle that the entry is now even better, you may want to cut losses if you think the trade sucks, , you may want to wait and see, the list is endless. If you can master the art of position management then you can make a lot of money.