Pre-open session
The 15-minute call auction that sets each stock's opening price.
Market structure
Live NSE examples below
What is Pre-open session?
Before continuous trading starts at 9:15 am, NSE and BSE run a pre-open call auction. Between 9:00 and about 9:08 orders are entered, modified and cancelled (the entry window closes at a random moment in the last minute to discourage gaming); the exchange then computes a single equilibrium price that matches the most volume and executes matched orders at it. A short buffer follows before normal trading. The auction's indicative prices are the earliest read on how each stock will open.
Formula
Equilibrium price = the price that maximises tradable quantity from the pre-open order book
Gap % = (opening price − previous close) ÷ previous close × 100
How to read it
- Large buy-side imbalances in pre-open often lead to gap-up openings.
- Indicative prices can change sharply until the order-entry window closes.
- Gaps that hold through the day (close above the open) are stronger than gaps that fade.
Common mistakes
- Treating early indicative prices as certain. Orders can be modified or cancelled until the window closes.
Live: NSE stocks matching this today
Gap-up stocks in the latest session 486
| Stock | Change % | Gap % | Relative volume (RVOL) |
|---|---|---|---|
| KSHINTLKSH International Limited | +9.51% | +9.93% | 8.67× |
| PWLPhysicswallah Limited | +3.76% | +9.88% | 5.64× |
| JASHJash Engineering Limited | +7.24% | +9.61% | 8.92× |
| HARIOMPIPEHariom Pipe Industries Limited | +11.36% | +9.44% | 72.22× |
| SANATHANSanathan Textiles Limited | +6.03% | +9.18% | 3.92× |
| LENSKARTLenskart Solutions Limited | +4.15% | +8.74% | 5.88× |
| KOTICKothari Indl | +10.00% | +8.48% | 0.29× |
| FAZE3QFaze Three Limited | +4.07% | +7.97% | 6.30× |
