Mumbai, Aug. 20 -- The Securities and Exchange Board of India (SEBI) has asked stockbrokers to update their system to accept trade orders during the initial few minutes of the closing auction session (CAS), two people aware of the development said. "Starting September, we will begin accepting aftermarket orders between 3:15 and 3:20 pm. The move is expected to improve price discovery and liquidity in CAS," said Dhiraj Relli, managing director and chief executive officer at HDFC Securities. The initial 5 minutes of the 20-minute-long CAS are dedicated to the calculation of the reference price and the transition to the auction system. CAS begins at 3:15pm and ends at 3:35pm. The acceptance of after-market orders will help discover prices more accurately as liquidity improves. Mint reported on August 17 that most local traders and retail investors had stepped aside from the CAS window, making it the leanest trading period of the day. Low liquidity in the auction session has led to unusual price swings and concerns around market manipulation. SEBI has ruled out abandoning the framework. Chairman Tuhin Kanta Pandey on Monday said SEBI will not simply shut the closing auction down due to market pushback. The framework was first introduced by SEBI in a circular in January 2026 and began operating on August 3. Under CAS, buy and sell orders are pooled during a dedicated end-of-day window and matched at an equilibrium price that allows the maximum volume of shares to trade. The mechanism is aimed at improving price discovery and bringing India's market closer to practices followed in other major markets. For example, if buyers are willing to buy 1,00,000 shares at Rs.100 and sellers are willing to sell 1,00,000 shares at the same price, then Rs.100 becomes the equilibrium, or closing, price. No trades happen during the auction itself. Instead, all eligible trades are executed at once at the final price. The session currently covers 208 derivative-traded stocks and replaced the longstanding volume-weighted average price (VWAP) system for determining closing prices. An emailed query to SEBI did not elicit an immediate response....