What is Market order?
An order that executes immediately at the best available price. Fast and certain to fill — but pays the "taker" fee and, in thin markets, a worse price than you saw quoted.
A market order says "fill me now at whatever the market offers" — it takes the best available orders off the book immediately. Certainty and speed are the product; the costs are the taker fee and, in thin markets, slippage: a large market order eats through the order book, each successive fill at a worse price.
For small trades in deep markets — a few hundred dollars of BTC on a major exchange — market orders are fine; the convenience costs pennies. The damage happens at the intersection of size and thinness: a big market order in a small coin is a donation to whoever placed the resting orders. If your trade is large relative to what's on the book, split it or use limits.
See it in practice
Related terms: Limit order · Slippage · Order book · full glossary
FAQ
Why did my market order fill at a worse price than shown?
The displayed price was the best order's price — your order consumed it and kept filling at the next levels down the book. That gap is slippage, and it grows with order size and market thinness.
Are instant-buy buttons market orders?
Functionally similar but usually worse: instant-buy interfaces add a spread margin on top. On platforms offering both, the order-book interface's market order is typically the cheaper of the two conveniences.
General information only, not financial advice. Definitions are maintained in our fact database and reviewed with the daily rebuild.