A market order is an order to buy or sell a stock at the current market price.

The market order is the simplest of order types. Think of it like pressing the go or stop button to trade.

It's an order to execute a trade as soon as possible, with a minimum of delay and does not provide any discretion for time or price.

An order to ‘buy at market,’ means that you buy at the current offer price, which will be the lowest offer price displayed on your monitor. Likewise, an order to ‘sell at market’ will lock you in at the highest bid price. “For example, if the bid/offer spread in BHP is currently 2701/2704, an order ‘to buy 2000 BHP at market’ would be filled at 2704. Of course, there are times when an order may not be filled due to a lack of liquidity – for instance, the offer volume to buy 2000 BHP may be currently insufficient, sitting at just 575. Remember to check the price depth window before placing a market order.