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Key Takeaways
- A market order requests prompt execution at available prices without a limit price.
- A buy executes against sell interest; a sell executes against buy interest.
- Add all partial fills to calculate the order’s volume-weighted average price.
- The worked 600-share buy costs $15,072.50 and averages $25.1208.
- Compare the final execution with the reference price selected before submission.
What is a market order?
A market order is an instruction to buy or sell a security promptly at the best prices reasonably available, without specifying a maximum buy price or minimum sell price. A buy seeks sell interest and a sell seeks buy interest, so a large order can fill at several prices. The order prioritizes prompt execution over control of the price.
Formula
Buy slippage = volume-weighted average fill price − decision price- The volume-weighted average fill price combines all partial fills by their share or contract quantity.
- Decision price can be the quote midpoint, displayed offer, or another benchmark chosen before the order is sent.
Market order example: a 600-share buy across three prices
In a fixed-book example with zero fees, a 600-share market buy fills against 200 offered at $25.10, 250 at $25.12 and 300 at $25.15.
- First fill: 200 × $25.10 = $5,020.00
- Second fill: 250 × $25.12 = $6,280.00
- Third fill: 150 × $25.15 = $3,772.50
- Average fill: $15,072.50 / 600 = $25.1208 per share
The 600-share order fills 200, 250 and 150 shares across the three prices. It costs $12.50 above buying all 600 at the initial $25.10 offer, or 2.08 cents per share. The final level retains 150 shares.
The order record connects the submitted quantity with each completed execution. Multiple fills belong to one complete quantity and average-price calculation.
The fixed-book example fills 200 shares at $25.10, 250 at $25.12 and 150 at $25.15. The respective costs are $5,020, $6,280 and $3,772.50.
Total cost is $15,072.50. Divide by 600 to obtain an average price of $25.1208. The final displayed level retains 150 shares.
Relative to buying all 600 at the initial $25.10 offer, the additional cost is $12.50, or 2.08 cents per share. This example sets fees to zero.
Market order vs limit order
A market order carries no limit price. A marketable limit order crosses available liquidity up to its maximum buy price or down to its minimum sell price. Choose the instruction together with the intended quantity and entry or exit objective.
The broker routes the order and the venue applies its session rules and execution controls. Review the final acknowledgment and fills to establish the completed position.
Market orders for options
For options, confirm the underlying, strike, expiration and contract quantity. Convert every fill to cash with the contract’s specified multiplier. Options flow shows contract activity, and the options profit calculator compares entry premiums and payoffs using the actual fills.
Limitations of market orders
- Use a marketable limit when the trade needs a price ceiling or floor. A market order has neither: the worked 600-share buy paid up to $25.15 against an initial $25.10 offer because the order used three price levels.
- The quote at submission moves before the fill when the market is fast, and a thin book widens that gap. Size a market order to the displayed depth.
- The $15,072.50 cost prices a book that holds still. Arriving, canceled and executed orders change the levels while yours fills, so read the cost from the fill report.
- Fix the decision price before you send the order. A midpoint benchmark and an offer benchmark produce different slippage for the same fills.
Bottom line
A market order buys or sells promptly at the prices available, which suits liquid securities and orders small enough for the displayed size. Check the spread and displayed size before sending it, add every fill to find the average price, and use a marketable limit order when the trade needs a price limit.
Clear answers
Frequently Asked Questions
Sources and Further Reading
- SEC: Trade Execution
- Cboe: U.S. Equities Order Types and Routing
- Cboe: Titanium U.S. Equities BOE Specification
How entries are sourced, calculated and updated: editorial methodology.