“Yawn- We Are On!” : What’s the Pre Market Session!

You may have watched on business news channels a pre-open session for NSE and BSE from 9.00 AM to 9.15 AM during market days and seen some crazy volatility even as your broker says “market nahi khula”. Do you know how this session operates? If  you don’t, here’s  brief!

NSE and BSE introduced the pre-open call auction sessions from October 18, 2010. This follows the international practice where the pre market open sessions are fairly long Although the stock markets in the U.S. open at 9:30 am on weekday mornings, it is possible for investors to begin trading before the opening bell and it takes place between 7:00 a.m. and 9:30 a.m, depending on the market. Pre-market stock trading on the NYSE takes place between 8:00 a.m. and 9:30 a.m . The Nasdaq market, begins pre-market trading at 7:00 a.m. You’ll have to get up early, but not as many traders participate in pre-market stock trading as during normal business hours.

In India , this session  starts at 9.00 am.

Why have this session?

Market experts believe that the introduction of pre-open session assumes special significance, especially, in situations when there is any major event or announcement comes overnight before the normal market opens. Such special events may be announcements of mergers and acquisitions, open offers, delisting, debt-restructurings, credit-rating downgrades or any rumours regarding any of such events.

On a normal day with no major event before 9:00 a.m., this pre-open session may appear to be a non-event and a routine exercise. However, on a day when there is any major outcome before the market hours this mechanism assumes special significance.

Pre-open session starts in the morning at 9.00 AM to 9.15 AM during the market days. This 15 minutes consists of mainly 3 slots including a) an order collection period till 9.08 am, b) order matching period 9.08 am till 9.12 am and c) the buffer period from 9.12 am to 9.15 am , a period where the market transitions to the normal market and prepares for the big bang at 9.15 am.

9.08 am onwards is the period where the Open price for each stock is determined using something called the equilibrium price / call auction method. It follows the concept of the multilateral order matching i.e it will find a price at which max orders will be executed rather than bilateral matching.

9.12 AM to 9.15 AM is called the buffer period and which facilitates transition from pre-open to normal market session.

Orders are not accepted after the initial 8 minutes ends. During the order matching session, Limit orders will get priority over market orders at the time of execution of trades . Also, all orders shall be disclosed in full quantity.  In the next four minutes, orders are matched, executable price is discovered and trades are confirmed.

How Price is determined

Instead of executing trades right from the get go, Pre-opening call auction takes all orders and then arrive at an equilibrium price. The equilibrium price is the price at which the maximum number of shares can be traded based on the demand and supply quantity and the price.

The basic principle behind the call auction period is very simple – amidst the wild swings and illiquidity, try and determine the price that best represents what should be the open price.

The order book is therefore evaluated as per a hierarchy which broadly resembles the following flow

  1. Find the price which has the maximum tradable quantity basis the buy and sale prices put and if found, that’s the price or if two such prices there then:
  2. 2) Find the price at which the minimum unmatched quantity exists basis the buy and sale prices and if found, that’s the price or if two such matches exist then,
  3. 3) The price closest to previous day’s close to be fixed as the final price
  4. And  if still you cant get to a price, take the previous day’s price as the open price

After finding the equilibrium price or call-auction price all market orders are executed at the equilibrium price and all no executed limit orders are carry forwarded to open market as they are and enter the market at the open rates.

A Price band of 20% shall be applicable on the securities during pre-open session.

Prabhudas Lilladher clients can participate in this session by calling any of our dealers or via our mobile app (www.plindia.com/plmobileapp) as well as place orders post market close (Called After Market Orders) similarly (till 6.15 am the next day)

Read more about the Pre Open session at https://www.nseindia.com/live_market/dynaContent/live_watch/pre_open_market/pre_open_market.htm



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