Closing Auction Session (CAS) to be Introduced for F&O Stocks from August 3

From August 3, 2026, stock exchanges will introduce the Closing Auction Session (CAS) for F&O-eligible stocks. Under the new mechanism, regular trading in these stocks will end at 3:15 PM, after which the official closing price will be determined through a dedicated auction process.

Key Changes

Who Will Be Impacted?
Intraday Traders

• Trading in eligible cash market stocks will now end at 3:15 PM.
• Broker square-off timings for MIS/intraday positions may be revised.
• Pending stop-loss orders in eligible stocks may be cancelled before the auction session begins.
   

F&O Traders

• Cash market closes at 3:15 PM, while derivatives continue till 3:40 PM.
• The auction-determined closing price will be used for settlement and expiry calculations where applicable.
   

Delivery Investors

• There is no change to holdings or settlement.
• Only the method of determining the official closing price changes.
   

Securities Covered

The Closing Auction Session will initially apply only to stocks that are part of the F&O segment. Stocks outside the eligible list will continue to follow the existing market closing process.

What Should Investors Do?
Check whether your stock is covered under the CAS framework.
Be aware of revised broker square-off timings for intraday positions.
Place auction orders well before the closing window ends.
Review any pending stop-loss orders in eligible stocks before 3:15 PM.