Periodic call auction is a special trading mechanism where stocks trade in scheduled auction sessions instead of continuous trading throughout the day. SEBI introduced periodic call auctions to reduce volatility in illiquid stocks. Stocks that meet specific illiquidity criteria move to this trading category, including those with fewer than 50 average daily trades and daily trading volume below 10,000 shares.
How periodic call auction works
The exchange conducts six auction sessions throughout the trading day, with each session lasting one hour, starting at 9:30 AM. These sessions work similarly to the pre-market session for equity stocks. During auction sessions, you might see bids and offers displayed at ₹0 because the system initially prices market orders at zero in the pre-market session.
Trading session schedule
| Session | Order placement | Order matching | Buffer period |
| 1 | 09:30 AM - 10:15 AM | 10:15 AM - 10:23 AM | 10:24 AM to 10:30 AM |
| 2 | 10:30 AM - 11:15 AM | 11:15 AM - 11:23 AM | 11:24 AM to 11:30 AM |
| 3 | 11:30 AM - 12:15 PM | 12:15 PM - 12:23 PM | 12:24 PM to 12:30 PM |
| 4 | 12:30 PM - 01:15 PM | 01:15 PM - 1:23 PM | 01:24 PM to 01:30 PM |
| 5 | 01:30 PM - 02:15 PM | 02:15 PM - 2:23 PM | 02:24 PM to 02:30 PM |
| 6 | 02:30 PM - 03:15 PM | 03:15 PM - 3:23 PM | 03:24 PM to 03:30 PM |
How to trade stocks in periodic call auction
You can place, modify, and cancel your orders during the 45-minute trading window. The system matches all received orders within the following eight minutes and confirms the resulting trades. A seven-minute buffer period follows before the next session begins.
To buy or sell stocks under periodic call auction:
- Place your order within the first 45 minutes of any session
- Wait for order matching during the eight-minute matching period
- Your order executes based on successful matching with other orders
If your order remains unexecuted during a session, the system automatically retries execution in subsequent sessions throughout the day. To learn more, refer to BSE FAQ and NSE website.
IOC (Immediate or Cancel) and GTT orders will be rejected even if triggered for stocks under the periodic call auction category.