Starting 3 August 2026, the Indian stock market is introducing a Closing Auction Session (CAS) for Equity Stocks on which futures and options are allowed in Equity (capital market) segment. There will be no CAS in Futures and Options Segment. This change aims to make the closing price of stocks more transparent, efficient, and resistant to price manipulation.
CAS shall be made applicable in a phased manner in other Equity Shares.
Why is the Closing Price Important?
The closing price of a stock is used for several critical purposes, including:
- Calculating Nifty and Sensex indices
- Determining Mutual Fund NAVs
- Final settlement of F&O contracts
- Portfolio valuation and P&L reporting
- Valuation of pledged securities used as collateral
A fair and accurate closing price is therefore essential for all market participants.
What is Changing?
Earlier, the closing price was determined using the Volume Weighted Average Price (VWAP) of trades during the final trading period.
Under the new mechanism, eligible stocks will enter a Closing Auction Session after regular trading ends. During this auction, buy and sell orders are matched at a single equilibrium price, which becomes the official closing price.
Impact on Market Timings
| Category |
Timings |
| Equity Stocks on which futures and options are allowed |
9:15 AM. – 3:15PM. |
| All other Equity Stocks |
No Change. |
| Index and Stock Futures and Options |
9:15 AM. – 3:40 PM (Closing time increased by 10 min and will close after closure of equity segment) |
| Post Closing Session in Equity Segment |
3:50 pm to 4 PM (earlier 03:40 pm to 4 pm) |
The Intraday Square off timing
| Category |
Timings |
| Non-CAS Equity Stocks |
3:15 PM. (NoChange) |
| CAS Equity Stocks |
3:10 PM (advanced by 5 min) |
| FNO Segment |
3:30 PM (postponed by 15 min) |
Closing Auction Timeline
| Time |
Activity |
| 3:15 PM – 3:20 PM |
Transition & Reference Price Calculation |
| 3:20 PM – 3:25 PM |
Order Entry (Market & Limit Orders) |
| 3:25 PM – 3:30 PM |
Limit Orders Only (Random Close any time from 03:28 PM) |
| 3:30 PM – 3:35 PM |
Order Matching & Closing Price Discovery |
Key Points for Traders
- Applicable initially only to F&O eligible stocks (Category I).
- Regular trading for these stocks ends at 3:15 PM.
- The Equity Derivatives market continues till 3:40 PM.
- The closing price will be determined through an auction rather than continuous trading.
Benefits of CAS
- Better price discovery through collective order matching.
- Reduces the impact of last-minute trades on closing prices.
- Improves transparency and market integrity.
- Helps institutional investors execute large orders more efficiently.
- Aligns Indian markets with global exchanges that already follow auction-based closing mechanisms.
Conclusion
The Closing Auction Session is an important step towards improving the quality of price discovery in the Indian equity markets. While retail investors may notice only a slight change in trading timings for eligible stocks, the new process is expected to result in more accurate closing prices and a more robust market structure.
Understanding this change will help traders and investors better plan their end-of-day trading activities and adapt to the new market timings.
For Details on Closing Auction Session from exchanges kindly refer the below circulars.
