There is no guarantee that an order will be filled at a target price. That is, a buy order could be filled at a much higher price than intended, or a sell order can be filled at a much lower price than intended.

Using Market Orders during a volatile market is not recommended as there is a higher probability that the prices will change quickly.  Hence, the incidence of ‘slippage’ is higher in fast-moving markets or for illiquid securities with thin order book and wide bid-ask spread.

The order may be split across multiple investors on the other side of the transaction, resulting in different prices for the order.