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 44
| Stock | Change % | Gap % | Relative volume (RVOL) |
|---|---|---|---|
| SHAILYShaily Engineering Plastics Limited | +3.66% | +7.84% | 6.37× |
| JASHJash Engineering Limited | +10.51% | +5.73% | 104.95× |
| SHIVALIKShivalik Rasayan Limited | +7.22% | +5.35% | 2.07× |
| STALLIONStallion India Fluorochemicals Limited | +4.99% | +5.00% | 1.28× |
| TIRUPATIFLTirupati Forge Limited | +4.99% | +4.99% | 0.54× |
| MCLEODRUSSMcleod Russel India Limited | +4.99% | +4.99% | 0.13× |
| STLNETWORKSTL Networks Limited | +4.98% | +4.98% | 0.41× |
| NIBENIBE Limited | +6.53% | +4.90% | 6.82× |
