Mumbai, June 1: The National Stock Exchange of India (NSE) will extend equity derivatives trading hours to 3:40 pm from the current 3:30 pm cut-off, as part of its rollout of the Closing Auction Session (CAS) in the equity cash segment, effective August 3, 2026. The change, detailed in an NSE circular dated May 29, 2026, affects all equity derivative instruments including index futures and options, and stock futures and options.
Currently, the equity cash market closes at 3:30 pm and the closing price of a stock is calculated using the volume-weighted average price (VWAP) of the last 30 minutes of trading. Under the new framework, stocks that have active derivative contracts will move to a CAS-based closing price mechanism instead.
The CAS will run as a separate 20-minute session from 3:15 pm to 3:35 pm on all trading days. During this window, all buy and sell orders are collected and then matched at a single equilibrium price the price at which the maximum volume of orders can be executed. This equilibrium price becomes the official closing price for eligible securities, replacing the existing VWAP-based method.
The session initially covers only F&O stocks. Non-F&O securities will continue to trade in the Continuous Trading Session (CTS) until 3:30 pm, with their closing prices determined under the existing mechanism.
Key Changes at a Glance
- Equity derivatives trading hours: Extended from 3:30 pm to 3:40 pm for all index and stock F&O contracts.
- CAS window: 3:15 pm to 3:35 pm for F&O stocks in the equity cash segment.
- Price band during CAS: +/3% from the reference price, fixed and not subject to dynamic flexing.
- Derivatives closing price: Unchanged continues to be VWAP of trades between 3:10 pm and 3:40 pm.
- Pre-open session changes: A separate realignment of the pre-open auction session framework will follow on September 7, 2026.
- Mock sessions: NSE plans 2-3 mock trading sessions before the August 3 go-live date.
The NSE has clarified that CAS and BSE will run their closing auction sessions independently, meaning reference prices and closing prices may differ across the two exchanges. Client code modification cutoff time remains unchanged at 4:15 pm.
Source:
- NSE Circular NSE/CMTR/74466 dated May 29, 2026 | NSE FAQ on CAS dated May 29, 2026
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