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Stock Market · Introduction to Stock Markets

Pre-open session

From 9:00 to 9:15 AM, the market is not open yet. It's in a different mode: price discovery.

The four phases

1. 9:00 AM → 9:05 AM. Market and limit orders. Place, modify, or cancel orders freely. Nothing executes yet. All orders sit in a queue.

2. 9:05 AM → 9:10 AM. Limit orders only. The exchange rejects market orders from here. Entry shuts at a random moment between 9:08 and 9:10, so nobody can game the last second.

3. 9:10 AM → 9:12 AM. Price discovery. The exchange takes all the queued orders and calculates the price at which the maximum number of shares can trade. That becomes the opening price, and matched orders fill at it.

4. 9:12 AM → 9:15 AM. Buffer. Orders locked. System prepares for live trading.

9:15 AM: normal trading starts. Orders that did not match carry over into it.

Why this exists

If news drops while the market is shut (election exit polls, a global crash, big earnings after close), markets need a controlled way to absorb that information before live trading goes chaotic. Without the pre-open session, the 9:15 AM open would be a price-discovery explosion.

Exit polls landed on a Saturday in June 2024. That Monday the Nifty opened about 3.5% higher, at a record. The pre-open had priced in the news before a single trade in the normal session.

Practical tip

If you want to buy at or near the open, place a limit order in pre-open, not a market order. A market order at 9:15 in a volatile session can fill ₹5–10 above where you expected.

8 to 10 minutesYour window to place orders before price is set

0Trades that execute during order collection phase

Takeaway. The pre-open session sets the opening price using accumulated overnight demand, not live trading.