TL;DR: A market order tells your broker to buy or sell a set number of shares right away at the best price currently available. It does not set a price. If you buy 50 shares while the market price is around $20, the cost is about $1,000 before fees, since 50 multiplied by $20 equals $1,000, labelled approximate because a market order fills at the next available price, which may be slightly higher or lower than the quote you saw. Market orders suit liquid stocks when getting the trade done matters more than the last few cents of price. They are a poor fit for thinly traded stocks, fast moving openings, and any moment when the price could move sharply before your order fills.
Key Takeaways
- A market order prioritises execution. A limit order prioritises price. You choose which certainty matters more for each trade.
- The fill price is the next available price, not a guaranteed quote. In calm, liquid stocks the difference is usually small. In thin or fast markets it can be material.
- Market orders are simplest for small orders in widely traded stocks during regular market hours.
- The bid ask spread is a real cost on every market order, even when no commission is charged.
- If the exact price matters to your decision, use a limit order instead, as explained in what is a limit order.
How does a market order actually fill?
When you place a market order to buy, your broker routes it to be filled against the best available selling prices at that moment. If there are not enough shares at the best price to complete your order, the remainder fills at the next prices up, so a large order can fill at several prices, with the average reported back to you. The same applies in reverse when selling.
Illustrative example only: a stock is quoted at around $20 and you place a market order for 50 shares. At exactly $20 the trade would cost $1,000 before fees, since 50 multiplied by $20 equals $1,000. Because the order fills at the next available price rather than at a promised $20, your actual fill might be at $20.05 or $19.98, making the real cost slightly different. That approximation is not a flaw in the example. It is the defining feature of the order type: speed and completion first, price second.
The bid ask spread sits underneath every fill. The bid is the highest price buyers currently offer, the ask is the lowest price sellers currently accept, and a market buy fills at the ask side. In a liquid stock the spread might be a cent or two. In a thin stock it can be wide enough that a market order pays a visible premium over the last traded price. Checking the spread before you trade is the cheapest piece of diligence there is, and it belongs in the same pre trade routine as the checks in our stock research checklist.
When is a market order the sensible choice?
For a small order in a large, liquid stock, during regular hours, when your decision does not depend on a few cents of price, a market order is reasonable and often the simplest route. Long term investors adding to a position they intend to hold for years are usually in this position: the difference between filling at $20.00 and $20.10 matters far less than the quality of the decision itself.
Market orders become risky in four situations. First, the market open, when overnight news is being priced in and quotes move quickly. Second, thinly traded stocks, where few sellers means your own order can push the fill price up. Third, very large orders relative to normal trading volume, for the same reason. Fourth, outside regular hours, where liquidity is thinner and prices can gap, as covered in our guides to stock market hours and premarket and after hours trading. In any of those four, a limit order gives you a ceiling on what you will pay, at the cost of possibly not filling at all.
How is a market order different from a limit order?
A limit order sets the maximum you will pay to buy, or the minimum you will accept to sell, and fills only at that price or better. It gives price control and removes execution certainty. A market order does the opposite: execution is the priority and price is whatever the market offers next. Neither is better in general. They answer different questions. If being in the position matters more than the entry price, the market order fits. If the investment case only works at or below a certain price, the limit order is the honest expression of that case, because a market order would fill you at a price where your own analysis said not to buy.
A common middle path is a limit order set slightly through the current price in a liquid stock. It behaves almost like a market order in normal conditions, while still blocking a freak fill far from the quote during a sudden spike. Many experienced investors use that as their default for exactly that reason.
This article is educational information about how order types work, not financial advice and not a recommendation to buy or sell any security. Order handling details vary by broker and exchange, so read your broker's own definitions before relying on them.
Sources and method
- Target keyword: "what is a market order" from .saeo/keywords.yaml (queue entry added 2026-10-29). No search volume or difficulty figure is claimed; both are recorded as unknown in the queue entry.
- All prices are labelled illustrative examples. Arithmetic verified for this draft on 2026-10-29: 50 multiplied by $20 equals $1,000. The total is described as approximate in the article because market order fills occur at the next available price.
- Internal links checked against existing drafts in this folder on 2026-10-29: what-is-a-limit-order, stock-research-checklist-before-you-buy, stock-market-hours-explained, premarket-and-after-hours-trading-explained.
