The National Stock Exchange (NSE) on March 18, 2026, issued circular regarding the Operational guidelines and Standard Operating Procedure (SOP) on Introduction of Closing Auction Session (CAS) in the Equity Cash Segment.
The National Stock Exchange of India Limited has issued detailed operational guidelines for the Closing Auction Session (CAS) in the equity cash segment, in line with Securities and Exchange Board of India circulars. CAS will be introduced in a phased manner, initially for stocks with derivatives.
The reference price for CAS will generally be based on the VWAP of trades between 3:00 PM and 3:15 PM, with fallback to last traded price or previous close if no trades occur. A price band of ±3% from the reference price will apply during CAS in both cash and futures segments (with aligned methodology), while options pricing remains unchanged.
Only limit and market orders will be allowed in CAS; stop-loss and disclosed quantity orders are not permitted. Importantly, algo market orders will be allowed in CAS (and later pre-open sessions) without penalties, unlike in the regular trading session.
The closing price of eligible stocks will be determined through the CAS equilibrium price mechanism; if not available, the reference price or last available close will be used. The exchange will also disseminate indicative prices, volumes, imbalance data, and index values during CAS to enhance transparency.
[Circular No: 38/2026]
