Ever noticed market prices moving even before trading officially begins? That’s the effect of the pre open market session. This short period creates a fundamental impact, establishing trading conditions throughout the daily market. Understanding this short trading session enables traders of all types to manage the market better.
Let’s break down what happens during this 15-minute window—and why it matters more than it seems.
What Is the Pre Open Market Session?
The pre open market session is a short trading window before the normal market hours begin. It’s available on major stock exchanges like NSE (National Stock Exchange) and BSE in India.
This session stabilises prices and reduces volatility from overnight news, global market movements, or macroeconomic events.
Why Does It Exist?
The Indian stock market introduced the pre-open session to avoid sharp price swings at the market opening. Here’s why it helps:
- Global events (overnight) can lead to panic trades.
- Company announcements made after hours can cause price gaps.
- Without this phase, opening prices might be based on speculation.
NSE Pre Open Market Timing
Here’s a breakdown of the pre open market session on NSE:
| Phase | Time Slot | Purpose |
| Order Entry Phase | 9:00 AM – 9:08 AM | Investors place buy/sell orders |
| Order Matching Phase | 9:08 AM – 9:12 AM | Orders are matched, and the opening price is set |
| Buffer Phase (Optional) | 9:12 AM – 9:15 AM | Transition time before the normal market |
After 9:15 AM, the regular trading session begins.
Key Features of the Pre-Open Session
Here’s what makes the pre-open session unique:
- No live trading: You place orders, but they are executed only after matching.
- Price discovery: The system calculates the opening price based on demand and supply.
- Limited to select stocks: Pre-open is typically active for NIFTY 50 and other large-cap stocks.
- Order types allowed: Limit orders and market orders can be placed.
Types of Orders Allowed
You can place the following types of orders in the stock market during the pre-open session:
| Order Type | Description |
| Limit Order | Set a maximum buy or minimum sell price |
| Market Order | Executed at the opening price derived from price discovery |
| Cancel/Modify Order | Possible only during the 9:00 AM – 9:08 AM phase |
After 9:08 AM, no order modifications are allowed.
How Is the Opening Price Decided?
The exchange follows a call auction mechanism. Here’s how it works:
- All buy and sell orders are collected between 9:00 and 9:08 AM.
- A price is determined where the maximum volume can be traded.
- This becomes the opening price for that stock.
Opening Price Determination Example
| Price | Buy Qty | Sell Qty | Tradable Qty |
| 98 | 500 | 100 | 100 |
| 99 | 800 | 200 | 200 |
| 100 | 1000 | 1000 | 1000 |
Here, ₹100 is the price where the maximum quantity can be matched. Hence, it becomes the opening price.
What Happens If No Match Is Found?
If there are no matching orders for a stock in the pre-open market:
- The order is carried forward to the normal market (post 9:15 AM)
- It retains its order priority and executes accordingly
Difference Between Pre-Open and Post Market Session
| Aspect | Pre-Open Session | Post Market Session |
| Timing | 9:00 – 9:15 AM | 3:40 – 4:00 PM |
| Purpose | Price discovery before the market opens | Order placement after the market closes |
| Order Types Allowed | Market & limit orders | Only delivery-based limit orders |
| Execution Time | At market open (after 9:15 AM) | The next day at the market open |
Should Retail Investors Participate?
Most retail investors skip the pre-open session, but if you:
- React to major overnight events
- Want the opening price without chasing market volatility
- Trade in large-cap stocks (e.g. NIFTY 50)
Platforms like Dhan allow users to place orders even during the pre-open window. This gives retail investors access to more professional trading behaviour without added brokerage on delivery trades.
Tips for Using Pre-Open Session Effectively
Here are some safe trading practices to follow:
- Avoid rushing: Let the price discovery process settle before placing large orders.
- Use limit orders: They offer better control than market orders in this session.
- Check liquidity: Not all stocks are active in this phase, so focus on large-cap names.
- Watch for news: Earnings reports, policy updates, and global indices affect opening volatility.
- Review before 9:08 AM: After that, orders cannot be changed or cancelled.
Master the Pre-Open Market
Although the pre open market session lasts only briefly, it establishes lasting consequences during market hours.
The opening trade occurs during this session, supporting supply and demand equilibrium while safeguarding against abrupt market fluctuations.
Understanding this market session gives investors a strong advantage because it builds their knowledge better than average investors.
