Direct Answer
A market order is an instruction to buy or sell a stock immediately at the best price currently available, prioritizing speed over an exact price. It typically fills near the current bid or ask, but the last quoted price is not a guaranteed execution price, so the actual fill can differ from what was displayed, a gap known as slippage.
Key Takeaways
- A market order emphasizes speed over price control and generally executes near the current ask (buying) or bid (selling), not the last traded price shown on a quote screen.
- Slippage is the difference between the expected trade price and the actual average execution price; the page's worked example shows a 100-share buy filling at an average of $50.038 against a $50.00 last price.
- A large order can consume shares from several price levels at once, producing multiple executions and one average fill price rather than a single clean price.
- Risks increase in thinly traded stocks, during volatile markets, and in premarket or after-hours sessions where liquidity is thinner and spreads are wider.
- A market order is best suited to liquid stocks with narrow spreads where completing the trade matters more than a small price difference; extra caution applies around major news or a volatility halt reopening.
What Is a Market Order?
A market order is an instruction to buy or sell a stock immediately at the best price currently available.
Market orders emphasize speed rather than precise price control. They generally execute near the current ask price when buying and near the current bid price when selling. However, the last price displayed on a quote screen is not a guaranteed execution price.
Market Order Example
Assume a stock shows a last traded price of $50.00, a current bid of $49.98, and a current ask of $50.03.
You submit a market order to buy 100 shares. Your order attempts to purchase shares from the lowest-priced available sellers. You might receive:
- 60 shares at $50.03
- 40 shares at $50.05
Your average execution price would be $50.038 per share, even though the displayed last price was $50.00. This difference is called slippage.
Advantages and Risks of Market Orders
Advantages
- High probability of immediate execution
- Simple to place
- Useful when entering or exiting a liquid stock quickly
- Appropriate when completing the trade matters more than a small price difference
Risks
- Execution price is not guaranteed
- Slippage can increase during volatile markets
- Large orders can fill at several different prices
- Thinly traded stocks may have wide bid-ask spreads
- Prices can change between submitting and executing the order
- Premarket and after-hours liquidity may be limited
By the time an order reaches the market, the available price can differ from the price displayed when you clicked buy or sell.
When Does a Market Order Make Sense?
A market order may be appropriate when the stock is highly liquid, the bid-ask spread is narrow, the order is small relative to normal trading volume, you need to exit a position promptly, or a minor price difference matters less than completing the trade.
When should you be careful with a market order?
Use extra caution when trading a low-volume stock, trading immediately after major news, trading during a volatility halt reopening, entering a large order, trading during premarket or after-hours sessions, the bid-ask spread is unusually wide, or the market is falling or rising rapidly.
When Immediate Execution Is Worth Paying For
A market order is the right tool in a narrower set of circumstances than its default status suggests. It fits when being out of, or into, a position matters more than the last fraction of the price, and when the instrument is liquid enough that the difference between the quote and the fill is negligible.
Check the two conditions before using one. Look at the current spread relative to the price, and look at the size resting at the best quote relative to your order. A tight spread with size several times your order means the fill will land near the quote. A wide spread or a quote holding less than you are buying means the order will walk up the book, and the average price can be materially worse than the number on the screen.
The misreading is treating the displayed quote as the price you will receive. That quote is the best price for a limited quantity at a moment that has already passed by the time the order arrives.
Market orders are also at their least predictable when they are most tempting: at the open, immediately after news, during a halt reopening and in the final seconds of a session. Those are the conditions where books thin and the gap between quote and fill widens.
Market Order FAQs
Does a market order guarantee execution?
A market order usually has a high probability of execution during an active market, but execution isn't absolute in every circumstance. Trading halts, unavailable liquidity, market closures or brokerage restrictions can prevent or delay it. The execution price is never guaranteed.
What is slippage?
Slippage is the difference between the expected trade price and the actual average execution price. It's more likely during volatile markets, low-liquidity periods, wide spreads and large orders.
Can a market order fill at multiple prices?
Yes. A market order, or any sufficiently large marketable order, can consume shares from several price levels, producing multiple executions and an average fill price.
Why did my market order execute above the last traded price?
The last traded price reflects a previous transaction, not a promise for your next one. By the time your order reaches the market, the best available bid or ask can already differ from the price you last saw quoted.
What is market impact?
Market impact occurs when a market order is large relative to a stock's typical daily volume, so it consumes available orders at progressively worse prices as it fills, moving the market against you in the process. It's distinct from ordinary slippage and is most pronounced in thinly traded stocks or with orders that are large relative to normal trading volume.
Why do brokers warn against market orders at the opening bell?
The first minutes of the session are when overnight news is repriced, the opening auction has just cleared, and quoted spreads are typically at their widest of the day. A market order entered into that environment accepts whatever the book offers at that moment, which can differ substantially from the previous close or from the pre-market indication. Waiting for the book to settle, or using a limit, removes the part of the outcome you have no control over.
What does it mean when a market order fills better than the quoted price?
This is price improvement, and it happens when the venue executing your order matches it inside the publicly quoted bid and offer. It can come from a market maker filling at a better price than the national best quote, from an order that was resting hidden between the quotes, or from a mid-point match. Price improvement is a normal feature of how orders are routed rather than an error, though the amount varies by broker, venue, and stock.
Are market orders cheaper than limit orders?
Explicit commissions are usually identical, but the total cost is not just the commission. A market order pays the spread by definition, since it crosses to the other side of the book. A resting limit order that fills may avoid that cost or even earn a rebate on some venues. The correct comparison is the all-in cost including the spread, which is why the apparently free market order is often the more expensive of the two on liquid stocks.
Can a market order be rejected?
Yes. Brokers reject market orders when a stock is halted, during certain auction periods, in extended-hours sessions where many firms accept limit orders only, when the position would breach a margin or risk check, and sometimes on very thinly traded or restricted securities. A rejection is a control working rather than a malfunction, but it means the assumption that a market order is always available does not hold.
References
The order-type definitions and execution mechanics on this page follow long-standing, widely documented U.S. equity market conventions. Key reference sources include:
- U.S. Securities and Exchange Commission, Investor.gov, Types of Orders: investor.gov: the SEC's investor-education explanation of how market, limit, and stop orders work and how price and time priority determine fills.
- FINRA, Order Types and Trading Education: finra.org: the self-regulatory organization's guidance on order types, marketability, and time-in-force conventions used across U.S. brokerages.