Market order

A market order instructs a broker to buy or sell a stock immediately at the best available current price, without specifying a particular price the way a limit order does. It is the simplest and generally the fastest order type to get filled, since it accepts whatever the market is offering right now rather than waiting for a specific price to be reached.

Speed and certainty of execution are the tradeoff for giving up price control. In a heavily traded, liquid stock, a market order typically fills almost instantly at a price extremely close to the last quoted price, since there is usually plenty of size available right at the top of the order book. In a thinly traded stock, or during a fast moving, volatile session, a market order can execute at a noticeably worse price than expected, because the order may have to fill against several price levels deeper in the book to find enough shares, a phenomenon often described as slippage.

Market orders are commonly used when an investor's priority is simply getting into or out of a position quickly and the exact fill price matters less than actually completing the trade. For situations where price matters more than speed, particularly in less liquid stocks or around volatile news events, a limit order is generally the safer choice, since it prevents the kind of unexpected price a market order can produce in a fast market.