Slippage

Slippage occurs when a trader (or investor) attempts to enter or exit a position at a specified price but gets a worse price than intended. If the trader is long then this will happen if there are no buyers at the price that the trader wants to exit the trade or if all the buyers' orders are absorbed by other sellers that got there before him.

If the trader is trading an electronic market through the internet then this is more likely to happen with slower connections because it means that the trader's order will take longer to get the market.

In rare cases slippage can be positive when the market touches the trader's stop price (triggering the stop order) and then trades back up. By the time the trader's order is received by the exchange the market price is better and the trader exits with positive slippage.