What Is the Pre-Open Session?
The 15 minutes before markets open set the opening price. Here’s how the pre-open session works.
On this page
The pre-open session is a short window before regular trading begins (9:00–9:15 a.m. for equities in India) used to discover a fair opening price and absorb overnight news in an orderly way.
Why it exists
Without it, a flood of orders at 9:15 reacting to overnight events could cause wild, erratic opening prices. The pre-open session collects orders first, then calculates a single equilibrium opening price — smoothing the start of the day.
The three parts
- Order entry (≈9:00–9:08) — investors place, modify and cancel orders. No trades happen yet.
- Order matching (≈9:08–9:12) — the exchange computes the equilibrium price that maximises traded quantity; opening trades are confirmed at this single price.
- Buffer (≈9:12–9:15) — a transition into normal continuous trading.
What it means for you
- The opening price you see at 9:15 comes from this process, not the previous close.
- Orders placed in the pre-open can be at limit or market; limit orders give you price control.
- Big overnight news (results, global cues) shows up as a gap at the open, discovered here.
Most long-term investors don’t need to trade the pre-open, but understanding it explains why a stock can open far from yesterday’s LTP. Education only, not advice.
