Every trading day starts with a short 15-minute window before the market opens. This is called the Pre-Open Session. It also shows you whether a stock has moved up or down since yesterday’s close, and it feeds into where the Nifty and Sensex open.

From September 7, 2026, the timings inside this window are changing. You don’t need to do anything this article just explains what’s different, in simple terms.

Before and after: the timing changes

So in short: your Market order window is 3 minutes shorter (ends at 9:05 AM instead of 9:08 AM), and order matching starts 2 minutes later (9:10 AM instead of 9:08 AM). The full session still runs 9:00 AM to 9:15 AM.

Order type rules

• No iceberg orders. Every order placed in Pre-Open must show its full quantity, you can’t disclose only part of it.
• No stop-loss orders. These aren’t allowed during Pre-Open. Place them after 9:15 AM, once normal trading begins.
• Algo-based Market orders are now allowed in Phase 1 (9:00–9:05 AM). Earlier, algo-tagged Market orders were blocked in this window that restriction has been removed.
• Market orders get matched before Limit orders. If you have both pending at the same time, your Market order will be filled first.

What this means for you?

• Less time for Market orders. Earlier, you could place a Market order until 9:08 AM. Now that window closes at 9:05 AM after that, only Limit orders can be placed.
• Place Limit orders early. Between 9:08 AM and 9:10 AM, the exchange can stop accepting orders at any moment, not necessarily right at 9:10 AM. Try to place or update your Limit orders before 9:08 AM to be safe.
• Confirmations arrive a little later. Order matching now starts at 9:10 AM instead of 9:08 AM, so your opening price and trade confirmation will show up a couple of minutes later than before. This is expected.