A Buy Market Order or Sell Market Order is an order to buy or sell a specified quantity of a cryptocurrency at the best available price in the Order Book. Depending on the specified quantity, the order will be filled beginning with the best price available, and if that price is no longer available, the remainder of the order will continue to be filled with the next best price in the order book and so on.
Depending on the size of the order and the volume and prices in the Order Book at the time of order submission, a market order can result in a trade with a worse price (than the best price in the market), in some cases, significantly so.
Buy Market Order example
On the order slip below, the user has selected the Market Order type for the BTC/USD cryptocurrency trading pair.
The user has specified that they intend to purchase $75,000 worth of BTC at the best available price in the market which is shown as the Best ask of $55130.04
If the user hits the BUY BTC button, they are shown how much BTC they are likely to receive based on the current prices in the order book
Sell Market Order example
On this order slip, the user has specified that they intend to sell 0.5 BTC at the best available price in the market which is shown as the Best bid of $54,985
If the user hits the SELL BTC button, they are shown how much USD they are likely to receive in exchange based on the current prices in the order book.