NSE Reports Strong Participation on Day 1 of Closing Auction Session for F&O Stocks

The National Stock Exchange (NSE) has reported strong participation on the first day of the Closing Auction Session (CAS) for F&O-eligible stocks, which came into effect on August 3, 2026, under the Securities and Exchange Board of India's (SEBI) revised market framework. 

According to an NSE press release dated August 3, 2026, 515 trading members participated in the inaugural Closing Auction Session, placing orders for 56,773 unique PANs. The exchange said participation exceeded that of the day's pre-open session, where 403 trading members placed orders for 42,822 unique PANs. 

Closing Auction Session Sees Strong Debut 

The Closing Auction Session was introduced to improve price discovery, transparency, and market efficiency in determining the closing price of F&O-eligible stocks. 

NSE noted that despite being the first day of implementation, participation was encouraging and is expected to increase as market participants become more familiar with the new framework. 

How the Closing Auction Session Works 

Under the revised framework, the Closing Auction Session is conducted from 3:15 PM to 3:35 PM on trading days for F&O-eligible stocks. 

The session is divided into the following phases: 

Meanwhile, the equity derivatives (F&O) segment continues trading until 3:40 PM. 

Read More: NSE IPO Update: SEBI Agrees to ₹1,491.21 Crore Settlement; What It Means for the IPO 

How the Closing Price Is Determined 

NSE said the closing price is determined using an equilibrium price mechanism, where the price with the highest executable order volume becomes the official closing price. 

The reference price for the auction is based on the Volume Weighted Average Price (VWAP) of trades executed between 3:00 PM and 3:15 PM. If no trades occur during this period, the stock's last traded price (LTP) is used as the reference price. 

The exchange also stated that only market orders and limit orders are permitted during the Closing Auction Session. Orders such as stop-loss and iceberg orders are not allowed. 

NSE Explains Index Movement During CAS 

NSE clarified that investors should correctly interpret index movements during the Closing Auction Session. 

Since there is no continuous order matching between 3:15 PM and 3:30 PM, the displayed index remains unchanged during this period. However, indicative values based on continuously calculated equilibrium prices are available on the exchange's website until the final auction price is determined. 

Conclusion 

The first day of the Closing Auction Session for F&O-eligible stocks witnessed participation from 515 trading members and 56,773 unique PANs, according to NSE. The exchange said the new mechanism aims to improve transparency and price discovery, while participation is expected to increase as investors and market participants adapt to the revised trading framework. 

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