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Market Intelligence › Basic Terminologies
How the opening price is formed, and what you can do in that window
Published by The Retail Trader · AUG 09, 2026 · Order Flow
The market opens at 9:15, but its opening price is not formed at 9:15. It is set in the fifteen minutes before that, by a separate process called the pre-open session.
The first eight minutes are for order entry — orders come in, get modified, get cancelled, but no trade happens.
After that, order matching takes place and a single equilibrium price is determined, at which the largest quantity can be matched. That becomes the opening price.
A few things work differently in this session:
• The last minute is a buffer — orders cannot be modified in it.
• Orders that do not match at the equilibrium price carry over into the normal session.
• On days with a big gap, this is where real price discovery happens.
• Not all stocks are in the pre-open — it depends on the exchange's list.
Taking decisions by treating the pre-open indicative price as final is wrong — it moves a lot in the last seconds. And in the first two or three minutes right after 9:15 the spread is widest, so a market order there gives the most expensive fill.
This article is for education only — it is not a buy or sell recommendation, makes no claim of guaranteed returns, and is not advisory. Rules, rates and mechanics change from time to time with the exchange, SEBI and RBI, so verify every number yourself with your broker or an official source.