Check this Zconnect post on after market orders.
Generally, the Indian stock markets operate from 9.15 am to 3.30 pm during the weekdays. Constant news updates and corporate announcements after the market hours often make you wonder if you can actually buy or sell stocks before the market even opens.
For example, when a company has reported poor quarterly results post the trading hours, investors would want to sell their holdings immediately. Under such conditions, you do not have to wait until the next day for the market to open. You can place after-market orders which will get executed the next trading day at the open.
Also for busy people who don’t have access to the regular market working hours or someone who is living overseas can benefit in placing after-market orders. You may set after market orders with your brokerage usually from 4.00 pm to 9.15 am.
Unlike standard orders, after-market orders are not instantly sent out to the stock exchange. They are sent before the next trading session opens. So, the equilibrium price for these orders is not determined in the live market session and is actually formed in the pre-market trading session that runs from 9.00 am to 9.15 am.
You can position aftermarket orders with your brokerage any time after the stipulated time mentioned there. Most of the brokerages allow after-market orders so you should check the timings for the same with them.
When you place an after-market order, consider the closing price of the stock and select accordingly. You can choose a price which is 5% lesser or higher than the closing price.