The National Stock Exchange (NSE) will implement a pre-open session for equity derivatives from December 8, 2025. The mechanism aims to improve price discovery and market stability. A mock session is scheduled for December 6, 2025, to help members prepare.
 Source: NSE F&O Circular Press Release (NSE Exchange Fillings) | Published on Nov 03, 2025
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As quoted in the press release of NSE (NSE Exchange Filings), it will implement a pre-open call auction session for equity derivatives on Monday, December 8, 2025. NSE intends to facilitate better price discovery and market opening in an orderly manner for futures contracts on indices and single stocks. In preparation for the new session, a mock session will also be held for trading members on Saturday, December 6, 2025.
As stated by the exchange, the pre-open session will be held between 9:00 a.m. and 9:15 a.m., prior to the regular continuous trading session. The pre-open session will consist of a call auction system, and orders will be collected prior to the market opening where an equilibrium price will be determined.
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Effective date: December 8 2025.
Mock session: December 6 2025.
Duration: 9:00 a.m. – 9:15 a.m. (includes order entry, matching, and buffer phases).
Coverage: Current-month futures on indices and single stocks.
Exclusions: Options, spreads, and far-month contracts.
The pre-open call auction is separated into three distinct phases:
Order Entry Phase (9:00 a.m. – ~9:08 a.m.) - Traders are permitted to submit, modify, and cancel limit and market orders. The closing of these orders will occur in a random manner between the seventh and eighth minute in order to deter last-minute price manipulation.
Order Matching Phase (~9:08 a.m. – 9:12 a.m.) - The subsequent phase of order matching will occur to discover a single equilibrium price, to maximize the volume of the aggregates, minimize imbalance, and be as close as possible to the previous closing price.
Buffer Period (9:12 a.m. – 9:15 a.m.) - The final buffer period is intended to be the period in which orders that do not match are transferred to the continuous session and market orders that did not match become limit orders at the price that was discovered.
The current-month (M1) futures of indices and single stocks will be the initial subject to the pre-open mechanism. M2 futures will also apply for the last 5 trading days of each expiry cycle. Options, spreads, and M3 contracts will still be excluded.
Category  | Included Instruments  | Notes  | 
Current-Month Futures (M1)  | Index and single stock futures  | Applicable throughout the month  | 
Next-Month Futures (M2)  | Enabled only in last 5 trading days before expiry  | 
  | 
Far-Month Futures (M3)  | Excluded  | 
  | 
Options and Spreads  | Excluded  | Not part of pre-open call auction  | 
All tick size, lot size and price bands will remain the same as the regular market session. Pre-trade margin validation will apply to all orders, and if the margin is insufficient, the order will not be accepted. Market Price Protection (MPP) and Limit Price Protection (LPP) assume the equilibrium price as the trigger to engage once continuous trading begins.
Self-Trade Prevention Check (STPC) will be in effect at the time of order entry to ensure the cancellation of executed self-matched orders. In the pre-open session, trades are unable to be cancelled.
The NSE has encouraged trading members to implement the modifications involving the updated contract files in their trading systems prior to the go-live date, as well as during the pre-open session publish indicative equilibrium prices and corresponding quantities, for enhanced transparency.
The action is structured to align the derivatives market more closely with the cash segment, which features a similar pre-open mechanism. The NSE anticipates that by gathering and publishing orders prior to the official opening, the movement into continuous trading is seamless and opening prices more stable.
Pre-open not conducted in futures of an underlying on ex-date due to scheme of arrangement.
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