Glossary · PSX Mechanics
Market Order
An instruction to buy or sell a security immediately at the best available current price. Guarantees execution but not the price at which the trade is filled.
01—What is Market Order?
The definition — and what it means in practice.
A market order is an instruction to buy or sell a security immediately at the best available price in the market. It is matched against existing orders in the order book, so it prioritises speed of execution over price control. A market order generally guarantees execution (if there is liquidity), but it does not guarantee the exact price you will receive, especially when prices are moving quickly.
Market orders matter because the final trade price can differ from the last quoted price due to the bid–ask spread and limited available quantity at each price level. In less liquid shares or during volatile periods, one market order can be filled in multiple parts at different prices (slippage). That uncertainty affects your costs when buying and the proceeds when selling, which can change your effective entry or exit price.
If you place a market buy for 100 shares and the best available seller is at Rs 50, you’ll get filled near Rs 50, but it can slip higher.
- Market orders aim for fast execution; price is not controlled.
- The fill price depends on the order book, not the last traded price.
- Bid–ask spread and low liquidity can increase slippage.
- Large orders may be filled in parts at multiple prices.
02—How market order works on the PSX
The Pakistan-specific rules, conventions, and numbers.
On the Pakistan Stock Exchange (PSX), a market order is executed by matching with available bids and offers during the trading session, including the pre-open and continuous trading periods. Because it consumes liquidity already in the order book, the execution price can move across levels if the quantity available at the best price is small relative to your order size.
PSX equities are subject to daily price limits (circuit breakers) for most shares of ±10% or Re 1 around the last day close price (LDCP), whichever is higher. These limits can constrain how far a market order can trade within the day, but they do not remove slippage within the permitted range. After execution, the trade follows the normal clearing and settlement cycle through NCCPL on a T+1 basis.
03—Common misconceptions
Where investors most often get this wrong.
A market order always fills at the last traded price.
It fills at the best available prices in the order book. If the best price changes or quantity is limited, the fill can differ from the last trade.
Market orders guarantee the exact price, only the timing varies.
Market orders prioritise execution speed. The exact price is not guaranteed and can vary due to spread, volatility, and available liquidity.
Slippage only happens in very small companies.
Slippage is more common in less liquid shares, but it can occur in any stock when the market moves quickly or the order size is large.
04—Using market order on BSL
Where this term shows up across the platform — with live data.
- Place and monitor orders from the live market view on Market.
- Compare faster execution versus price control by learning Limit Order.
- Sense liquidity conditions by checking which names are trading most on Most Active.
- Understand trading constraints by reading Circuit Breaker.
05—Frequently asked questions
What investors ask about market order on the PSX.
Frequently Asked Questions
A market order on the PSX is an instruction to buy or sell immediately at the best available price in the order book. It aims to execute quickly, but the final fill price can differ from the last traded price.
They are designed to execute quickly, but execution depends on there being enough opposing orders (liquidity) in the market. If there is no available quantity to match, the order may not fully fill.
The order matches available bids or offers, not the last trade. The bid–ask spread, limited quantity at the best price, and rapid price changes can cause slippage, sometimes resulting in multiple fills at different prices.
They serve different needs. A market order prioritises speed of execution, while a limit order prioritises controlling the price and may not execute if the market does not reach your limit.
Daily price limits for most equities restrict trading to a band around LDCP (±10% or Re 1, whichever is higher). A market order can still experience slippage within that allowed range, but it cannot trade beyond the limit.
06—Related terms
Keep building the picture.
An instruction to buy or sell a security at a specific price or better. The order is only executed if the market reaches the specified price, giving the investor control over the execution price.
A real-time electronic record of all buy and sell orders for a security on the exchange, showing prices and quantities at each level.
The highest price a buyer is willing to pay for a security. The gap between the bid and ask price is the spread and represents the cost of trading.
The lowest price a seller is willing to accept for a security. Also called the offer price. The difference between the ask and the bid price is called the spread.
The difference between the bid price and the ask price of a security. A narrow spread indicates high liquidity; a wide spread suggests lower liquidity and higher trading costs.
The ease with which a security can be bought or sold without significantly affecting its price. High-liquidity stocks have large trading volumes and narrow bid-ask spreads.
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