Introduction of the Closing Auction Session (CAS) as per SEBI Guidelines

As per the SEBI circular, the Closing Auction Session (CAS) will be introduced from August 3, 2026. Additionally, changes to the Pre-Open Auction Session will take effect from September 7, 2026.

Currently, the closing price of a stock is determined using the Volume Weighted Average Price (VWAP) of trades executed during the last 30 minutes of the regular market session. With the introduction of CAS, the closing price of eligible stocks will instead be determined through a dedicated auction session.

The key changes are as follows:

Closing Auction Session Timings

The Derivatives segment will continue trading until 3:40 PM.

The Post-Close Session in the Equity Cash segment will continue from 3:50 PM to 4:00 PM.

Important Points

• CAS will initially apply to the Cash segment on which derivative contracts are available.
• Regular trading in CAS-eligible stocks will end at 3:15 PM. Stocks not covered under CAS will continue trading until 3:30 PM.
• Orders for CAS-eligible stocks can be placed within a ±3% price range from the starting reference price.
• Market Orders and Limit Orders will be accepted during the applicable order-entry window.
• Stop-loss, Iceberg, and Disclosed Quantity (DQ) Orders will not be accepted during CAS.
• Eligible unexecuted Limit Orders from the regular market session that fall within the ±3% price range will automatically carry forward to CAS. Orders outside the applicable price range, along with Stop-loss and Iceberg Orders, will be cancelled.
• During CAS, buy and sell orders will be matched at a single matching price determined by the exchange. This will become the official closing price.
• If the exchange is unable to determine a matching price, the starting reference price will become the official closing price.

Note: Traders who wish to buy or sell eligible stocks near market close should plan their orders according to the revised market timings. Orders placed using features such as GTT, SIP, and Scheduled Orders may execute based on the updated market schedule. The revised market closing schedule will also impact intraday (MIS) auto square-off timings, as shown below.

Revised Intraday (MIS) Square-Off Timings

Effective from August 3, 2026

Changes to the Pre-Open Auction Session

Changes to the Equity Pre-Open Auction Session will come into effect from September 7, 2026.

The Pre-Open Auction Session will continue from 9:00 AM to 9:15 AM, with the following order-entry process:

Note: Stop-loss, Iceberg, and Disclosed Quantity (DQ) Orders will not be accepted during the Pre-Open Auction Session.

These changes are intended to enhance price discovery and improve the determination of opening and closing prices in the Equity Cash segment.

For complete details, please refer to the SEBI circular.