On What Basis Is The Equilibrium Opening Price Determined For Pre Open Session

Opening price is determined based on the principle of demand supply mechanism.

The equilibrium price determined in pre-open session is considered as open price for the day.

Maximum Volume:

The equilibrium price is the price at which the maximum volume is executable.

Minimum Order Imbalance (if multiple prices qualify):

In case more than one price meets the criteria, the equilibrium price is the price with minimum order imbalance quantity (unmatched order quantity)

Closest to Previous Closing Price:

In case more than one price has same minimum order imbalance quantity, the equilibrium price is the price closest to the previous day’s closing price.
In case the previous day’s closing price is the mid-value of pair of prices which are closest to it, then the previous day’s closing price itself is taken as the equilibrium price.
In case of corporate action, previous day’s closing price is adjustable closing price or the base price.

Orders Considered:

Both limit and market orders reckon for computation of equilibrium price.

Opening Price for the Day:

The opening price is determined based on the principle of demand and supply

The equilibrium price determined in pre-open session is considered as open price for the day.
In case only market orders exist both in the buy and sell side, then order is matched at base price. Therefore, Base price is the opening price.
In case no price is discovered in the pre-open session, the price of the first trade in the normal market will be considered as the opening price.