What Is a Market Order, and Why Can the Fill Price Change?
A market order asks the trading platform to buy or sell as soon as possible at the currently executable price. It prioritises execution rather than guaranteeing a specified price. Market orders are generally suited to situations where prompt entry or exit matters and liquidity is adequate. If price precision matters more, learn about limit orders and other order types. The platform's documentation defines the exact names and execution rules.
Why Can the Fill Price Differ from the Price at the Click?
Quotes keep changing, and there is a delay between clicking, sending and matching an order. If the market rises during that time, a buy may fill at a higher price; if it falls, the buy may fill lower. This is called slippage, which may be adverse or favourable. If the quantity available at executable quotes is limited, a large order may fill in parts at different prices, producing a weighted average fill. Fast markets, low-liquidity sessions, market opens and major data releases can amplify the effect through price jumps and wider spreads.
A Simple Example
Suppose a currency pair has a bid of 1.2500 and an ask of 1.2502, and you submit a buy market order. The offer quickly moves to 1.2504, so the order may fill near 1.2504 when it arrives. If there is not enough quantity available, part may fill at later quotes. If the platform offers a “maximum deviation” or “slippage tolerance” setting, an order outside the limit may be rejected or requoted. Not every platform supports this, and the setting does not guarantee a fill at its specified price.
Practical Checks Before Placing an Order
Confirm the instrument, side, quantity, leverage and available margin, and check whether quantity is measured in lots, shares, contracts or base-currency units. Observe the current bid-ask spread and consider waiting during major events or session changes. Use small or demo orders first to learn how the platform handles partial fills, rejection, price deviation and stops. Do not mistake a market order for a promise to fill at the screen price, or overlook position size and the maximum loss you can bear in pursuit of a fill.
The execution of a market order and a stop trigger is not always identical: a stop may become a market order after triggering, and in a rapid gap the actual fill may pass the trigger price. Rules vary for stocks, forex, futures, digital assets and jurisdictions; read contract specifications, execution policies and cost disclosures. This article is general education, not investment advice. Trading may result in the loss of some or all principal.