When you are trading I would suggest that you are careful when you use a market order. There are things call a micro crash and if you are trading and open or closing your trades using a market order it become costly to you.

A micro crash is when the price has changes a lot for just a second, due to mistakes in order entry, software problems or what ever else may cause the price to be significantly different than it was a moment ago. So listen to my suggestions on this podcast.