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Market Order vs Limit Order: Price Certainty or Fill Certainty

A market order fills but its price is not guaranteed; a limit order caps the price but may not fill. How each works, worked examples, and the trade-off.

By Published 4 min read

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AI-assisted article. Drafted with AI tools from the sources cited below and checked by automated tests and an AI editorial review. No person has reviewed it yet. How we write and check articles.

Key takeaways

  • A market order asks to buy or sell immediately at the best available price; it is almost always executed, but the price is not guaranteed.
  • A limit order sets the worst price you will accept: a buy limit fills at the limit or lower, a sell limit at the limit or higher, and it may never fill.
  • The last traded price is not necessarily the price a market order will receive, and a large market order can fill in parts at different prices.
  • Limit orders can also fill in part, leaving the rest open until it fills, expires or is cancelled.
  • The choice is a trade-off between certainty of execution and control of price; neither is better in every situation.

Every buy or sell starts with a choice: what kind of order to place. The two basic types make opposite promises. A market order promises that your trade will happen, but not at what price. A limit order promises a price, but not that the trade will happen. The SEC's investor education office describes both, and the differences explain many surprises on a first trading screen.

The market order: execution first

A market order is an order to buy or sell at the best available price, right away. The SEC's bulletin Understanding Order Types says it generally executes immediately, but its price is not guaranteed. Investor.gov's glossary adds that unless you specify otherwise, a broker will enter your order as a market order.

Two cautions from the SEC are worth memorising:

  1. The last traded price is not necessarily your price. A market order to buy generally executes at or near the current ask, and a market order to sell at or near the current bid, not at the "last" price shown in large type. The gap between bid and ask is the bid–ask spread.
  2. Large orders can fill in pieces. The bulletin's example: a market order for 1,000 shares placed when the best offer is $3.00 might fill 500 shares at $3.00 and the other 500 at a higher price, because only so many shares were offered at $3.00.

In a fast-moving market, the price can change between pressing buy and the order reaching the market, as described in how the stock market works.

The limit order: price first

A limit order is an order to buy or sell at a specific price or better:

  • A buy limit order can only execute at the limit price or lower.
  • A sell limit order can only execute at the limit price or higher.

The SEC's example: an investor who wants to buy ABC stock for no more than $10 can submit a limit order at $10, and it will only execute if ABC trades at $10 or lower. The trade-off is stated just as plainly: a limit order is not guaranteed to execute. It can only be filled if the market price reaches the limit, and even then there may not be enough shares at that price to fill the whole order.

The two side by side

Market order Limit order
Promise Execution Price no worse than the limit
Risk Paying more, or receiving less, than expected Not being filled at all, or only partly
Typical fill At or near the ask (buying) or bid (selling) At the limit or better, if the price is reached
Useful when Getting in or out matters more than a few cents The price matters more than the timing
Weak spot Fast markets, wide spreads, thinly traded stocks Prices that move away and never come back

A worked example

A stock shows a bid of $49.95 and an ask of $50.05, with a last trade at $50.00. You want 100 shares.

  • Market order to buy: you would expect to pay about $50.05 a share, the ask, so roughly $5,005 before costs. If the ask moves to $50.20 before your order arrives, you pay that instead.
  • Buy limit at $50.00: nothing happens unless someone is willing to sell at $50.00 or less. If the price rises to $51 and stays there, you never buy. If it dips to $49.90, you may buy at $49.90, better than your limit.

Neither order is "right". The first values getting the shares; the second values the price.

Partial fills and how long an order lasts

Both order types can fill in parts. A partially filled limit order leaves the remainder open. How long it stays open depends on its time-in-force instruction. The SEC bulletin explains that unless you specify otherwise, orders are day orders, which generally cancel at the end of regular trading hours, while a good-'til-cancelled order lasts until it is filled or cancelled, subject to the broker's own time limits. Time-in-force covers those instructions, including immediate-or-cancel and fill-or-kill.

Stop orders build on these two

Stop orders combine a trigger with one of these two types. A stop order becomes a market order when its stop price is reached; a stop-limit order becomes a limit order. The same trade-off carries over: stop orders versus stop-limit orders explains what happens to each when a price jumps.

Practising the difference

The quickest way to feel the trade-off is to place both orders on the same stock and watch what fills. Learn to Trade Stocks Beginner lets you practise market, limit and stop orders with a virtual balance. Bear in mind what a simulator cannot reproduce: real queues, real liquidity and real fills, the subject of what paper trading can and cannot teach. It is one of our education apps; the investing basics hub lists the other order guides.

Good to know

Frequently asked questions

What is the difference between a market order and a limit order?
A market order executes as soon as possible at the best available price, so execution is nearly certain but the price is not. A limit order executes only at your chosen price or better, so the price is controlled but execution is not guaranteed.
Why did my market order fill at a different price from the quote?
Quotes apply to a limited number of shares, and prices can move between placing the order and its execution. The SEC's investor bulletin notes the last-traded price is not necessarily the price a market order will get, and that parts of a large market order may fill at different prices.
Can a limit order fill at a better price than my limit?
Yes. A buy limit order can execute at the limit price or lower, and a sell limit order at the limit price or higher. The limit is the worst price you accept, not the exact price you will get.
What happens if my limit order is never filled?
It stays open until it expires or you cancel it. The SEC explains that unless you specify otherwise, orders are day orders, which generally cancel at the end of regular trading hours; a good-'til-cancelled order stays open longer, up to a limit set by your broker.

Sources

  1. Understanding Order Types – Investor Bulletin (opens in a new tab)Investor.gov, U.S. Securities and Exchange Commission — accessed
  2. Types of Orders (opens in a new tab)Investor.gov, U.S. Securities and Exchange Commission — accessed
  3. Market Order (glossary) (opens in a new tab)Investor.gov, U.S. Securities and Exchange Commission — accessed

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