Modifications in the Pre-open Call Auction Framework

FAQs on Pre-open Session in Equity (CM) Segment

Version 1.0

July 2026

(this FAQ shall be applicable w.e.f. September 07,2026)

Disclaimer: “This document/FAQ summarizes the queries relating to the above topic(s) in a concise manner for the Member’s ease of understanding. The information and/ or content (collectively ‘Information’) provided herein is general information only and NSE has issued detailed circulars to such effect from time to time. While reasonable care has been exercised to ensure that the Information is adequate and reliable, no representation is made by NSE as to its accuracy, correctness or completeness and NSE, its affiliates and subsidiaries accepts no liability of whatsoever nature for any direct/indirect or consequential loss, including without limitation any loss of profits, arising from reliance on this Information. In the event of any difference/ inconsistencies between the Information as provided herein and in the circulars, the Information in the circulars shall be construed as final and binding. NSE does not in any way control, warrant or provide guarantee on the suitability of the Information for the readers’ usage. The readers are expected to undertake their own diligence and are advised not to solely rely on this document. Any such reliance shall be at the reader’s own risk. Nothing stated herein shall bind NSE, in any manner whatsoever.”

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1. For which securities pre-open are applicable in equity market?

The pre-open session with call auction mechanism is applicable to all equity market securities including SME securities, partly paid-up securities, and InvITs/REITs.

2. What are the session timings?

The pre-open session shall be conducted using call auction mechanism for duration of 15 minutes i.e., from 9:00 am to 9:15 am. The pre-open schedule shall be as follows:

Note: In case of index-based market-wide circuit filter breach or any outage (stopping of trading, either suo moto by Exchange or by the virtue of reasons beyond control of stock exchange), the market shall open with a pre-open session, and its timings shall be informed separately on that day.

3. What shall be the trading parameters for pre-open session?

The below shall be the parameters applicable for pre-open session:

4. What shall be the indicator for identifying securities in pre-open and normal markets across specified files?

The below shall be the indicator for identifying securities in pre-open and normal market across the specified files:

5. How many sessions do Pre-open session comprise??

Pre-open session comprises of two sessions as mentioned below:

1. Order Collection Period
2. Order Matching Period

6. What are the features of order collection period in pre-open session?

• During this period orders can be entered, modified, and cancelled. • Order collection period ends by system driven random closure in the last 2 minutes. • Both Limit and market order are allowed as per applicable window timings provided in question number 2 above. • The information like Indicative equilibrium / opening price of scrip, total buy and sell quantity of the scrip, Indicative NIFTY 50 Index value & % change of indicative equilibrium price to previous close price shall be computed based on the orders in order book and are disseminated during pre-open session. Special term orders like Stop loss (SL), Immediate or Cancel (IOC) and Disclosed Quantity (DQ) shall not be allowed. • Algo market orders shall be allowed during initial 5 mins of order entry period when both limit and market orders are allowed. • When market orders are restricted, any market order placed shall be rejected by the Exchange with an appropriate error message on NEAT – “Market orders are currently not allowed.” • The information like Indicative equilibrium / opening price of security, total buy and sell quantity of the security and % change of indicative equilibrium price to previous close price shall be computed based on the orders in order book and will be disseminated during pre-open session.

7. What are the features of order matching period in pre-open session?

• Order matching period starts immediately after completion of order collection period. • Order will be matched at a single (equilibrium) price which will be open price. • Market orders shall be given priority over limit orders. The sequence for order matching shall be as under: ➢ Eligible market orders shall be matched with eligible market orders in the order of time priority at the equilibrium price. ➢ Residual eligible market orders, in the order of time priority, shall be matched with limit orders in the order of price-time priority. ➢ Remaining limit orders shall be matched with limit orders in the order of price-time priority. • During order matching period order modification, order cancellation, trade modification and trade cancellation are not allowed. • The trade details are disseminated to respective members before the start of normal market.