The National Stock Exchange (NSE) has changed the structure of its pre-open session from September 7, giving traders five minutes to place market and limit orders before restricting the session to limit orders. NSE has also introduced changes to the reference price and price-band calculation for stock and index futures from the same date.
Market and limit orders allowed until 9:05 am
Between 9:00 am and 9:05 am, both market and limit orders can be entered, modified and cancelled during the pre-open session.
From 9:05 am to 9:10 am, only limit orders can be entered, modified or cancelled. Market orders cannot be modified or cancelled during this period.
The order-entry period can also close randomly during the last two minutes of the 9:05 am to 9:10 am window under the exchange’s system-driven mechanism.
Order matching starts at 9:10 am
Order matching and trade confirmation will take place between 9:10 am and 9:12 am.
The opening price will be determined during this period, after which the 9:12 am to 9:15 am window will serve as a buffer period before continuous trading begins.
Market orders get priority during matching
NSE will give market orders priority over limit orders during the pre-open matching process.
Eligible market orders will first be matched with other eligible market orders at the equilibrium price according to time priority. Remaining market orders will then be matched with eligible limit orders based on price-time priority, followed by matching among the remaining limit orders.
NSE changes reference price for stock and index futures
Separately, an NSE circular dated September 3 has introduced changes to the reference-price calculation for stock and index futures, effective September 7.
The reference price will be based on the volume-weighted average price of trades executed in the respective futures contract between 3:00 pm and 3:15 pm. If there is no trade during that period, the last traded price of the contract during the day will be used.
If there is no trade in the contract during the day, NSE will use the prevailing theoretical price. For stock futures, the calculation will use the cash-market last traded price at 3:15 pm, while for index futures it will use the latest available actual index price. If the underlying price is not available, the base price of the respective futures contract will be used as the reference price at 3:15 pm.
Futures price band set at plus or minus 3%
NSE has also prescribed a price band of plus or minus 3% from the reference price for futures between 3:15 pm and 3:40 pm.
The existing framework for dynamic flexing of futures price bands will not apply during this period. NSE said the last half-hour of trading under the relevant framework will instead be considered as 2:45 pm to 3:15 pm.
The revised price band and the cancellation of outstanding orders outside the permitted range will be applied sequentially, meaning the changes will not take effect instantaneously at 3:15 pm.
Limit Price Protection ranges also change
NSE has made a related change to the calculation of Limit Price Protection (LPP) ranges for stock and index futures.
The LPP ranges will be recalibrated from 3:15 pm while the futures price band is being revised. The reference price for LPP will be calculated using the same methodology prescribed for the futures reference price.
What changes from September 7
The pre-open session continues to run from 9:00 am to 9:15 am, but the order-entry process is now divided into specific windows. Market and limit orders are available during the first five minutes, only limit orders are permitted in the following five minutes, and order matching takes place from 9:10 am to 9:12 am.
At the derivatives end, NSE has separately changed the reference-price methodology and introduced a plus or minus 3% futures price band for the 3:15 pm to 3:40 pm period. The exchange said all other provisions of its March 18, 2026 circular will remain unchanged.
Conclusion
NSE’s changes from September 7 cover both the pre-open order process and the treatment of futures during the final part of the trading day. The pre-open session now has defined order-entry and matching windows, while stock and index futures will use a revised reference price and a plus or minus 3% price band between 3:15 pm and 3:40 pm.