Quote from mindtrade:
What the OP is getting at is more often then not if you set a buy limit price and it gets hit the price will likely be one tick below your limit buy, putting you at an instant loss.
Not exactly . . . If you put in a limit order for 990.25 (ES), then you will be filled at that price or better. If you get filled at 990, then the price traded through your price and you actually got in at a better price. If you get filled at 990.25 and the price is instantly at 990 afterward, then that's just price moving against you. You expected 990.25 and got 990.25 . . . no slippage.
Slippage occurs with forms of market orders via buy/sell stop, market if touched, market buy/sell, etc. If price traded last at 990.25 and you buy with a market order and you are filled at 990.50, then that's 1 tick slippage. Market orders buy at the offer and sell at the bid . . . what ever the spread is will be your slippage in the best case scenario.
You can sit on the bid with a limit order in the ES and not get filled easy enough. Not quite as frustrating in the YM or NQ.
Keep trading.
JScott