What is Closing Auction Session (CAS) ?

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NSE has introduced a Closing Auction Session (CAS) framework in the equity cash segment for securities where derivatives are available. Alongside this, equity derivatives market timings will be extended till 3:40 PM to align with the revised closing process from 03 August 2026.

 

• Initially, CAS will apply only to cash market securities where derivative contracts are available.
• Non-F&O securities will continue to follow the existing closing mechanism.

 

Futures & Options market timings will be extended to 3:40 PM, this is applicable for Stock & index Futures & Options

 

Closing price in the cash segment for eligible securities will now be determined through Closing Auction Session (CAS) instead of the earlier methodology.

However, F&O closing price calculation remains unchanged and will continue based on VWAP of the last half hour (3:10 PM – 3:40 PM

 

Order restrictions

 

• No order entry allowed between 3:15 PM – 3:20 PM (transition period).
• Market & limit orders allowed between 3:20 PM – 3:25 PM.
• Only limit orders can be modified/cancelled between 3:25 PM till random market closure.
• IOC orders are not allowed during CAS.
• Stop-loss & disclosed quantity orders will be cancelled if ineligible