An order to buy or sell a security immediately at the best available current price, guaranteeing execution but not price.
A market order is an instruction to buy or sell a security immediately at the best available price in the Order Book. Unlike a Limit Order, a market order prioritises execution speed over price — you are guaranteed to get filled (assuming sufficient Liquidity), but the exact price may differ from what you see on the screen.
On the NSE and BSE, a market buy order is matched against the lowest ask (sell) price in the order book, and a market sell order is matched against the highest bid (buy) price. If the quantity at the best price is insufficient to fill your entire order, the remaining quantity fills at the next best price, and so on. This is why large market orders on illiquid stocks can experience slippage.
For highly liquid stocks like Reliance, TCS, or HDFC Bank, market orders typically execute within ₹0.05–₹0.20 of the displayed price — negligible for most investors. But for a small-cap stock with a bid-ask spread of ₹5, a market order could cost you significantly more than expected. In such cases, a limit order is preferable.
Indian brokers also offer the SL-M (Stop-Loss Market) order, which triggers a market order when a specified price is breached. For example, if you hold Infosys at ₹1,500 and set an SL-M at ₹1,450, when the price drops to or below ₹1,450, a market sell order is automatically placed. The actual execution price could be ₹1,448 or ₹1,445 depending on order book depth at that moment.
Market orders are best suited for: highly liquid stocks where the bid-ask spread is narrow, urgent situations where you need to exit immediately (e.g., a stop-loss trigger), and small order quantities where slippage is negligible. For larger orders or illiquid stocks, always prefer limit orders to control execution price.