I prefer limit trades so assuming this is my norm.... I will use Market orders to exit a stock quickly on occasion or when the spread is large and an exact price may not get filled. If market orders are allowed for buying then sometimes I will use a market order to get my position quickly on a breakout. Sometimes you can end up chasing prices with limit orders and this is what I am trying to avoid when I use market. Sometimes I simply want in/out RIGHT NOW regardless of price ... lol BTW, placing a limit buy order above the ask can insure a quick fill at the ask when needed. JIMO and FWIW