Sebi Backs Closing Auction Session Despite Early Market Volatility

The Securities and Exchange Board of India (Sebi) has defended the newly introduced Closing Auction Session (CAS), calling it a significant enhancement to India’s price discovery framework. In its latest annual report, the regulator said the auction-based mechanism is designed to deliver more transparent and reliable closing prices while bringing Indian equity markets closer to established global practices.

Invest in Indian Markets and Unlock Future Potential With 5paisa!

Open Account Now

The remarks come days after CAS was implemented, with the new system drawing attention following sharp index moves during the final minutes of trading. Market participants have been assessing its impact, particularly on derivatives contracts that are settled using the official closing index value.

Sebi Says CAS Strengthens Price Discovery

According to Sebi, the Closing Auction Session allows market participants to place buy and sell orders during a dedicated auction window instead of depending solely on transactions executed near the end of the regular trading session. The regulator said this approach is expected to improve the quality of closing prices by making the process more transparent, stable and efficient.

Sebi added that closing auction mechanisms are widely used across developed equity markets and that introducing a similar framework in India represents an important step towards strengthening market infrastructure.

Early Trading Sessions Show Higher Closing Swings

Initial trading data indicates that the Nifty recorded larger movements during the closing auction period than the Sensex. Over the first four trading sessions after implementation, the average difference between the Nifty’s level at 3:30 pm and 3:15 pm stood at 0.42%.

On the first day of the new framework, the index advanced by more than 200 points during the auction window. In the next session, another gain was noted of more than 150 points, whereas the third and fourth sessions had gains of about 50 points and 9 points, respectively. Closing auction turnover for the Nifty stood at nearly ₹1,433 crore on Thursday.

The Sensex displayed comparatively smaller changes during the same period. The average difference between its 3:30 pm and 3:15 pm levels over four sessions was around 0.10%. Even during its weekly expiry session, turnover in the closing auction was about ₹127 crore.

Derivatives Participants Assess the New Framework

The divergence in index movements has prompted traders to examine the role of liquidity, derivatives participation and index composition under the revised closing mechanism.

The change has been particularly relevant for options traders because settlement values are based on the final closing index level. Movements during the auction period can alter payouts for contracts trading near important strike prices. The participants in the market have been analyzing the correlation between futures and cash prices at the time of closing auction with changes in the settlement process.

Long-Term Perspective Dominates

According to Sebi, the focus of CAS was to enhance the efficiency of the closing price discovery process and not to regulate the short-term movements of the market. According to the regulator, the auction-based framework is expected to produce closing prices that are more transparent, stable and dependable over time.

As trading activity under the new mechanism evolves, market participants will continue to monitor whether early volatility moderates while the system delivers the stronger price discovery process outlined by Sebi in its annual report.