IPO pre-open session call auction listing price equilibrium price NSE BSE

Special pre-open session on IPO listing day

From WebNotes, a public knowledge base. Last updated 21 June 2026. Reading time ~12 min.

Key facts

What it is	A call-auction price-discovery window held before continuous trading on an IPO listing day
Session window	Begins at 9:00 AM IST; order entry runs for about 9 minutes 45 seconds with a random close between the 9:35th and 9:45th minute
Order type allowed	Only limit orders (including limit IOC); no market orders, and full quantity must be disclosed
How the price is set	Equilibrium price by volume maximisation: the single price at which the maximum quantity matches
Day-one price band	No standard circuit; initial dynamic price band of 25 to 75 per cent for mainboard, and minus 90 to plus 90 per cent for SME IPOs
After discovery	Matched orders execute at the equilibrium price; the scrip moves to continuous trading at that opening price

The special pre-open session on an IPO listing day is a call-auction window, run by the National Stock Exchange and the Bombay Stock Exchange , in which the listing price of a newly admitted scrip is discovered before continuous trading begins. It exists because a freshly listed share has no prior traded price to open against, so the exchange collects limit orders, computes a single equilibrium price that maximises the matched quantity, and uses that price as the opening price for the day.

This session is distinct from the regular daily pre-open that runs from 9:00 to 9:15 AM for already-listed stocks. The listing-day version applies to a first-time listing or a relisting, gives more time for order collection, and runs without standard circuit limits so the share can find a price across a wide range. This article sets out the schedule, the equilibrium-price logic, the order rules, and the day-one price bands, drawing on the NSE and BSE special pre-open framework.

Why a separate session exists

A newly listed share carries no previous closing price. The continuous market needs an opening reference, and for an established stock that reference is the prior close. For a listing, there is none. The exchange therefore runs a call auction that gathers buy and sell interest, computes one clearing price, and hands that price to the continuous market as the open. The mechanism turns a wide range of opinions, anchored partly by the grey-market premium , the subscription multiples, and broad market conditions, into a single number that the maximum volume of orders agrees on.

The session also absorbs the imbalance that a hot listing creates. When an issue is heavily oversubscribed, many investors who did not get an allotment want to buy, while anchor investor shares are locked in and cannot be sold on day one. The call auction nets this demand and supply at one price rather than letting the first few trades whipsaw the open.

The session schedule

The special pre-open session begins at 9:00 AM IST. The order-collection window runs for about 9 minutes 45 seconds and is closed by a random stoppage between the 9:35th and 9:45th minute of the session, a randomisation that prevents last-second order tactics from skewing the auction. During order entry the exchange disseminates an indicative opening price and the matchable quantity at regular intervals, so participants can see where the auction is heading and adjust their limit orders.

When the order window closes, the matching engine runs the auction and computes the equilibrium price. Matched orders execute at that single price, and the scrip then moves into the continuous trading session at that opening price. The headline takeaway for an allottee or a buyer is that the price-forming orders must be in during the early-morning window; once the random close triggers, no further orders shape the listing price.

Phase	What happens
From 9:00 AM	Order collection. Limit orders entered, modified, or cancelled. Indicative price and matchable quantity disseminated.
Random close, 9:35 to 9:45 minute	Order entry stops at a randomly chosen instant in this window.
After close	Equilibrium price computed by volume maximisation. Matched orders execute at that price.
Then	Scrip moves to continuous trading at the discovered opening price.

How the equilibrium price is set

The equilibrium price is the price at which the maximum executable volume is reached, the same volume-maximisation logic the regular pre-open uses. The engine aggregates all buy and sell limit orders into demand and supply schedules and finds the single price that matches the largest quantity. Every qualifying order matches at that one price, not at its own limit. A buy order entered at a limit above the equilibrium price still executes at the equilibrium price, and a sell order entered below it likewise executes at the equilibrium price.

Where two candidate prices would match the same maximum volume, the tie is broken by choosing the price closest to the base price; if the base price sits midway between the two, the base price itself is taken as the equilibrium price. Orders that cannot match at the equilibrium price, buys below it or sells above it, are not lost: when the price is determined, all unmatched orders within the applicable price range carry forward into the continuous market at their limit price, ranked by price-time priority.

If no equilibrium price can be discovered at all, the exchange cancels all outstanding orders and the scrip continues in the special pre-open session, repeating the process, until a price is found. Only then does continuous trading start.

Order rules in the session

The session accepts only limit orders , including limit immediate-or-cancel orders. Market orders are not allowed, because a market order carries no price and the auction needs prices to compute an equilibrium. Every order must disclose its full quantity; the revealed-quantity, or iceberg, function is disabled, so a participant cannot hide size during price discovery. Stop-loss orders and GTT triggers do not operate in the pre-open; they activate only in the continuous session. An allottee who wants to sell into the listing places a limit sell order during the order-collection window, choosing a limit at or below the price they will accept, since a lower limit still executes at the higher equilibrium price if one is discovered.

Price bands on the first day

No normal circuit limit applies to an IPO scrip during the special pre-open session. In place of a fixed circuit, the exchanges set an initial dynamic price band, an operating range, to block clearly non-genuine orders while still letting the share move widely. For a mainboard IPO , the initial dynamic price band is set uniformly across the exchanges in the range of 25 to 75 per cent. For an SME IPO , the initial dynamic price band is set at minus 90 to plus 90 per cent of the base price, a far wider range that reflects the thinner, more volatile SME market.

These operating ranges can be flexed in coordination between the exchanges during order collection, but no flexing is done in the final minute before the random closure, from the 9:35th minute onward, and for an SME IPO the ranges are not flexed at all. The wide day-one range is the reason a listing can open far above or far below the issue price without an immediate halt; the relaxed band is specific to the listing and the early sessions, after which the scrip moves to its standard circuit filter category.

Common equilibrium price across exchanges

Because an IPO can list on both the NSE and the BSE, each exchange runs its own call auction and matches its own orders, so the two can arrive at slightly different equilibrium prices. A reconciliation mechanism, set under the SEBI framework, handles a material gap. If the difference between the two exchanges’ equilibrium prices, measured as the absolute difference over the lower price, exceeds the applicable price band for the scrip, a common equilibrium price is computed as the volume-weighted average of the two exchange equilibrium prices, and the day-one band is set around that common price on both exchanges. This reconciliation does not apply to scrips on which derivatives contracts are available. For most retail allottees the single-exchange equilibrium price is what they trade against; the common-price mechanism matters only when the two venues diverge sharply.

Trading controls for small issues

For a small mainboard issue, with an issue size up to Rs 250 crore, trading on listing takes place in the trade-for-trade segment for the first 10 trading days, after which the scrip moves to the normal rolling segment. In the trade-for-trade segment every trade results in delivery, with no intraday netting, which is a control against speculative churn on a thin, newly listed counter. A block-deal session is not held on the first day of trading until the order matching and resulting price discovery are complete. These controls sit alongside the pre-open auction and shape how an allottee can transact in the first days after a small listing.

External references

References

NSE India, Special Pre-Open Session, capital market, and the Member Guide and FAQs on the Special Pre-Open Session in Capital Market, nseindia.com.
BSE India, Special Pre-Open, bseindia.com.
SEBI circular dated 11 April 2023 on call-auction price discovery and common equilibrium price across exchanges for listing-day pre-open.
SEBI Circular SEBI/HO/CFD/TPD1/CIR/P/2023/140 dated 9 August 2023, on the T+3 listing timeline within which the listing-day session falls.

Frequently asked questions

What is the special pre-open session on IPO listing day?

It is a call auction held before continuous trading on a newly listed scrip, run by NSE and BSE, to discover the listing price. Investors place limit orders, the exchange computes one equilibrium price that maximises matched volume, and all matched orders execute at that price.

What time does the IPO listing pre-open session start?

It begins at 9:00 AM IST. The order-entry window runs for about 9 minutes 45 seconds and closes through a random stoppage between the 9:35th and 9:45th minute, after which the exchange matches orders and the scrip moves to continuous trading.

How is the listing price discovered?

By volume maximisation. The exchange finds the single price at which the maximum quantity of shares can be matched between buy and sell orders. That price becomes the equilibrium price and the opening price; all qualifying orders execute at it, and it sets the reference for continuous trading.

Are there circuit limits on the first day of listing?

No standard circuit limit applies during the special pre-open session. The exchange sets an initial dynamic price band, 25 to 75 per cent for a mainboard IPO and minus 90 to plus 90 per cent for an SME IPO, to block non-genuine orders. Normal circuit filters apply from later sessions.

Can I place a market order in the IPO pre-open session?

No. Only limit orders, including limit immediate-or-cancel orders, are accepted during the special pre-open session. Orders must disclose full quantity; the revealed-quantity (iceberg) function is not allowed. A market order would have no price for the auction to use.

What if no equilibrium price is discovered?

If no equilibrium price can be found, all outstanding orders are cancelled and the scrip stays in the special pre-open session, repeating the process, until a price is discovered. Only then does it move to continuous trading.

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WebNotes Editorial Team

The WebNotes Editorial Team covers Indian capital markets, payments infrastructure and retail investor procedures. Every article is fact-checked against primary sources, principally SEBI circulars and master directions, NPCI specifications and the official support documentation published by the intermediary in question. Drafts go through a second-pair-of-eyes review and a separate compliance read before publication, and revisions are tracked against the SEBI and NPCI rule changes referenced in the methodology section.

Last reviewed: 21 June 2026
Conflicts of interest: WebNotes is independent. No relationship with any broker, registrar or bank named in this article.