A market order and a limit order are two instructions a broker sends to a trading venue. One instruction accepts the current price. The other instruction names a price boundary. Neither instruction sets the next trade by itself.
U.S. equity regular hours are 9:30 a.m. to 4:00 p.m. Eastern Time. The descriptions below follow the SEC staff bulletin on order types and FINRA’s order-type pages, as of October 2026.
How the two orders are structured
| Term | Market order | Limit order |
|---|---|---|
| Price | The price available at execution | A ceiling on a buy, or a floor on a sell |
| Execution | Generally immediate if the venue has a quote | Only if the market reaches the limit |
| Partial fill | Possible when size exceeds the displayed quote | Possible, unless a qualifier forbids it |
| Time in force | Often a day order | Day, or good-til-canceled within the firm’s limit |
| Main uncertainty | The price | Whether the order fills |
A market order asks for an execution now. The SEC bulletin says the execution price can differ from the last quoted price, especially in a fast market or in a stock with a wide spread.
- Priority: Market orders prioritize speed. They are designed for investors who want to enter or exit a position as quickly as possible.
- Execution: Investor.gov states that a market order generally executes immediately at the best available price. That price can differ from the quote the customer saw. FINRA says that during regular hours, 9:30 a.m. to 4:00 p.m. Eastern Time, the order generally executes at or near the current bid or ask. An order placed outside those hours can meet a different price when the market opens.
- Risk: The biggest risk of a market order is slippage. In a volatile market, the “best available price” can move significantly between the moment you place the order and the moment it is executed.
A limit order names the worst price the customer will accept. A buy limit executes only at the limit price or lower. A sell limit executes only at the limit price or higher. If the market never reaches that price, the order does not execute.
Both orders are messages. The venue matches them with opposite orders. The customer’s broker adds its own route, which order types covers beyond these two.
The structure is an instruction about price. The fill is a later event.
What actually happens when the order arrives
- Priority: Limit orders prioritize price. Investor.gov states that a buy limit can execute only at the limit price or lower, and a sell limit only at the limit price or higher, if the order executes at all.
- Terms: If you place a “Buy Limit” at $100, your order will only be executed if the price drops to $100 or below. If the price stays at $101, the trade will never happen.
- Certainty: A limit order may never execute. A day order that does not fill is canceled at the end of regular trading hours. A good-til-canceled order stays open until it fills, the customer cancels it, or the brokerage firm’s own time limit runs out. FINRA says firms typically set that limit at many months, not an open-ended order.
A market buy takes the shares currently offered, starting at the lowest ask, until the size is filled or the available quotes are exhausted. A market sell hits the bids the same way. The customer does not name the price in the instruction.
A limit buy rests on the book if the ask is above the limit. It becomes eligible when a seller is willing to trade at the limit or better. The order can wait through the session, or it can expire.
FINRA describes a day order as an order that ends with the trading day if it has not filled. A good-til-canceled order lasts until it fills, the customer cancels it, or the brokerage firm’s own time limit runs out. Firms commonly cap that life at a set number of months. The order does not rest forever by default.
A fill-or-kill qualifier, in FINRA’s description, requires an immediate fill of the entire size. Anything short of that cancels the order. A limit order without that qualifier can fill in pieces.
- Market Makers (The Providers): When you place a limit order that rests on the book, you are adding liquidity. That order waits for someone else to trade against it. In the maker-taker model described by the SEC staff, the venue pays a rebate to that resting order.
- Market Takers (The Consumers): When you place a market order, you are taking liquidity. You remove an order from the book. On a maker-taker venue, the taker pays a fee. Some venues invert the schedule and pay the taker instead.
The arrival of the order starts a match or a rest. It does not start a guarantee of the quoted price.
Where price, fees, and queue position move
The price on a market order is the liquidity that is displayed, plus any undisplayed size the venue executes against. In a thin stock, walking through several price levels changes the average fill. The quote the customer saw can be gone by the time the order arrives.
- Execution: The exchange will buy the 40 shares and leave the remaining 60 shares as an open limit order.
- Strategy: A “Fill or Kill” (FOK) order must be executed immediately and in full, or not at all. FINRA describes that qualifier as the instruction that prevents a partial fill.
The price on a limit order is the boundary the customer set. A buy limit at $20.00 does not pay $20.05. It also does not buy the shares if the ask stays at $20.05.
Maker and taker fees are a separate cash flow. An SEC staff memo on maker-taker fees describes venues that pay a rebate to the resting order and charge the order that takes liquidity. Some venues invert that schedule. The memo does not say that every exchange uses one schedule.
A resting limit order can receive a maker rebate or pay a maker fee, depending on the venue. A market order is typically a taker, because it removes the resting quote. The commission the broker charges is a third number, on top of the venue fee.
The customer sees a fill price. The venue fee and the broker commission are separate lines.
What can prevent or slice a fill
A market order can be rejected or delayed when the security is halted, when the venue is closed, or when the broker blocks the order outside the customer’s permissions. A market order in an extended-hours session follows that session’s rules, which are not the regular-hours quote.
A limit order fails to fill when the market does not trade through the limit. A partial fill happens when only part of the size is available at the limit and the order allows a partial. The rest stays open or cancels, according to the qualifier.
A gap through the limit does not give the limit order a better fill than the trades that actually occur. A sell limit at $20.00 does not sell at $25.00 merely because the stock opens there, if the opening mechanism matches at a different price or the order was not eligible for that auction. The auction rules of the venue decide.
Price improvement is possible. It is a property of the match, not a term of the market-order instruction.
Tradeoffs and constraints
A market order reduces uncertainty about whether a trade happens during the session, and it increases uncertainty about the price. A limit order reduces uncertainty about the worst price, and it increases uncertainty about whether a trade happens.
The two orders do not differ in what the customer owns after a full fill of the same size. They differ in the condition that produces the fill. A comparison with payment for order flow is a routing question. It does not change the definition of either order.
Quotes move. The displayed national bid and offer is a snapshot. The order type decides which snapshot the customer is willing to trade against.
