What is Closing Auction Session (CAS) ?
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
CAS shall not be applicable for stocks on which derivative contracts are available, in below scenarios:
• On the Ex-date of a scheme of arrangement, if the price is not determined during the SPOS for the eligible security.
• In case index circuit break is triggered and market halts trading for remainder of the day.
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