SEBI has proposed several changes to the Closing Auction Session that go beyond derivatives settlement, including tighter rules for certain orders and changes in the information displayed to traders.
The proposals come after the regulator reviewed the first phase of CAS implementation and received feedback from market participants.
The Closing Auction Session was introduced on August 3, 2026, with the aim of improving closing-price discovery in India’s equity cash market. The auction mechanism replaced the earlier approach of relying primarily on the volume-weighted average price during the last 30 minutes of continuous trading for eligible securities.
While the new mechanism was designed to improve transparency, the closing period also became a focus of market volatility concerns.
SEBI’s latest consultation proposes restrictions on the cancellation of limit orders that are positioned more than 1% away from the reference price. The objective is to prevent excessive or unusual order activity from affecting the price-discovery process during the auction.
Order behaviour is particularly important during a closing auction because a large number of orders are concentrated into a short period. The final equilibrium price is determined by matching available buying and selling interest.
If orders are repeatedly placed and cancelled, the displayed market picture may change rapidly. SEBI’s proposal is therefore intended to make the order book more stable and reduce the possibility of disruptive activity.
Another major proposal concerns the information displayed during the auction.
SEBI is considering discontinuing the display of the indicative index closing value during CAS. The regulator’s concern is that such information could be misunderstood by traders as an indication of the final index closing level, even though the auction process is still underway.
At the same time, indicative equilibrium prices for individual stocks may continue to be shown.
This distinction reflects the complexity of index-level price discovery. Individual stock prices are determined through their respective auction processes, while index values depend on the prices of multiple underlying securities.
SEBI is therefore examining whether displaying an indicative index value during the auction creates unnecessary confusion.
The regulator has also proposed changes to the post-closing auction period. Shortening this period could improve the transition between the cash-market closing mechanism and other market activities.
These changes are being considered alongside a major review of derivatives settlement.
One of SEBI’s main concerns is that derivatives expiry settlement became more sensitive after CAS was introduced. The regulator is considering two alternatives: a blended VWAP using both continuous trading and CAS activity, or an approach that temporarily relies only on the final 30 minutes of continuous trading.
The proposals are part of a broader effort to make the new system more stable.
SEBI has not indicated that CAS itself will be abandoned. Instead, the regulator appears to be refining its design after studying the impact of the first month of implementation.
This is significant because closing prices influence several areas of the financial market. They can affect derivatives settlement, index calculations, portfolio valuations and other investment-related processes.
A closing auction therefore needs to balance competing objectives. It should reflect genuine market demand and supply while avoiding excessive volatility, misleading information and disruptive trading behaviour.
For brokers and trading firms, changes to order cancellation rules could require modifications to trading systems and strategies. Algorithmic trading participants may also need to review how their systems interact with the revised auction rules.
For retail investors, the changes could affect the way prices appear during the final minutes of the session. However, the larger impact is likely to be felt by participants with significant exposure to derivatives and institutional closing transactions.
SEBI has invited comments from stakeholders until October 3. The regulator is expected to consider the feedback before finalizing the revised framework.
The consultation highlights an important feature of modern financial regulation: new systems often require adjustments after they are tested in live markets.
CAS was introduced to improve price discovery, but its interaction with derivatives and trading behaviour has generated new questions. SEBI’s latest proposals seek to answer those questions while retaining the central idea of a more transparent closing mechanism.
The final rules will determine how India’s markets balance efficiency, transparency and stability during the crucial closing phase of each trading day.
