Mumbai (Maharashtra) [India], August 31 (ANI): The National Stock Exchange's newly introduced Closing Auction Session (CAS) recorded a turnover of Rs 39,718 crore on Monday, its first major index rebalancing day since the mechanism was launched in Indian capital markets.

The closing auction accounted for 22 per cent of NSE's total cash market turnover during the day, while more than 98,000 investors participated in the session. CAS turnover was around 42 times the turnover recorded in the previous trading session, according to an NSE press release.

The sharp rise in activity came as the MSCI August 2026 Index Review took effect at the close of trading on August 31. This was the first index rebalancing after the closing auction mechanism went live.

Index rebalancing typically leads to heavy trading towards the market close as index funds, exchange-traded funds and other passive investors adjust their portfolios in line with changes in benchmark indices.

NSE said the exchange accounted for 99.9 per cent of CAS turnover on Monday.

The session also marked the completion of the first month of the new closing auction mechanism. During the period, NSE recorded cumulative CAS turnover of Rs 63,000 crore, with a market share of 98.2 per cent.

CAS is a mechanism under which buy and sell orders are brought together at the end of the trading session to determine the closing price of eligible stocks, instead of relying only on trades during continuous market hours. NSE said the mechanism is aimed at improving transparency and fairness in determining closing prices.

Sriram Krishnan, Chief Business Development Officer at NSE, said the first index rebalancing after the launch was an important test for the mechanism.

'The successful completion of the first month of the Closing Auction Session marks an important milestone for the Indian capital markets, and the confidence shown by the market on the first index rebalancing day after CAS went live is a strong endorsement of the mechanism,' Krishnan said.

He also thanked market participants, particularly index funds and passive investors, for using the mechanism during the rebalancing session and acknowledged the Securities and Exchange Board of India's role in introducing the closing auction framework. (ANI)