Quote from WinstonTJ:
Jack,
No idea what securities you are trading but in the equity world market orders are allowed to be held up for a period of time prior to acting on them. The market maker can sit on your market order, pull prices and then fill you at a (better for them, worse for you) different price.
If you read what I wrote you will see that I said MARKETABLE limit order. Pay through. If the stock is trading at 10.49 x 10.51 and you are trying to buy you send an order in to purcahse at $11. In the equity world you will get price improvement and you are required to be filled at the NBO vs. just a market order. Market orders can be held long enough that the market can pull the bid/ask back to a lower/higher price and fill you at $10.59 for example. If you had sent your order in to purchase at $11.00 you would have received price improvement down to the NBO and have been filled at $10.51.
Sending marketable limit orders is always going to be better (and will legitamitley get you filled faster) than a general market order.
If you aren't trading equities there is no reg nms so it's a moot point.
My views on stocks not as sophisticated as yours. My signal for entry lasts about 1 1/2 hours. In this period I make a decision and then price begins its move. The same is true for exits. So, mostly I am exiting to obtain capital to enter (long) a stock that will be performing better than the stock I am exiting. (Cross-over trading).