What is a market order?

You tap “buy” on the exchange, but what price will you actually pay?

With a market order, you ask for your trade to happen immediately, using the offers available at that moment. It’s not just for buying: you can place a market order to sell, too.

On an exchange with an order book, a buy order is matched first with the cheapest available sell orders. If those don’t cover the quantity you want, it moves on to the next, more expensive ones. Selling works the other way around: buyers offering the highest price come first.

Imagine you want ten identical items from a market stall. The first six cost €2 each and the remaining four €2.10. If you take them all, you pay €20.40 in total, or €2.04 per item on average. In the same way, a market order can be filled at more than one price.

Why it matters

Its defining feature is that it prioritizes execution, not price control. By contrast, with a limit order you set the maximum buy price or the minimum sell price, but a counterparty may not be found and the order may not execute.

We think this difference matters more than the convenience of an “instant buy” button. The price you see on the chart usually refers to the last trade, not necessarily the price at which your whole order can be filled.

What to watch out for

The gap between the expected and the actual execution price is called slippage. It can grow when there’s little liquidity, when the order is large relative to the available offers, or when the market is moving sharply.

In your final cost, factor in the exchange’s fee and the gap between the best buy and sell prices (the spread). Immediate execution isn’t guaranteed: insufficient liquidity, technical problems or the platform’s protection limits can prevent the order from filling completely. The trade preview is an estimate, not a price lock.