The Securities and Exchange Board of India (SEBI) has announced significant modifications to the closing auction session (CAS) aimed at improving the determination of settlement prices for derivatives on expiry days. The proposed changes include two methodologies for price determination, revised trading times, and updated rules regarding order cancellations, all of which could reshape trading behavior leading into market closures.
Proposed Methodologies for Settlement Prices
SEBI’s proposals focus on how settlement prices for index and single-stock derivatives will be established on expiry days. Two methodologies have been outlined:
- A blended volume-weighted average price (VWAP) method that combines trades from the last 30 minutes of continuous trading with the 10 minutes of the closing auction session.
- A reversion to the existing VWAP-based methodology, which could be in place for at least a year.
The blended VWAP method is designed to calculate the share of the settlement price based on actual traded values rather than fixed weights. For example, if 90% of trading volume is from continuous trading and 10% from CAS, the latter will only contribute 10% to the blended price.
Changes to Market Timings and Auction Dynamics
In addition to the new pricing methodologies, the proposals include alterations to market timings. SEBI is considering two options:
- Continuous trading in CAS stocks until 3:30 PM, followed by the auction and derivatives trading until 3:45 PM.
- Retaining the existing 3:15 PM cutoff for continuous trading in CAS stocks, with derivatives trading concluding at 3:30 PM.
Importantly, the transition period between continuous trading and CAS is set to be shortened from five minutes to just one minute. Furthermore, the post-CAS derivatives window is proposed to be reduced from ten minutes to five minutes. This swift transition aims to enhance liquidity and minimize volatility, especially during expiry days.
Regulatory Adjustments to Order Management
Another key aspect of SEBI’s proposals revolves around order management during the CAS. The regulator is suggesting:
- A restriction on the cancellation of orders placed more than 1% away from the reference price while still allowing modifications that improve prices.
- Conversion of unexecuted Iceberg orders at the start of CAS into normal limit orders, ensuring full disclosure.
These adjustments aim to enhance order execution efficiency and limit disruptive practices that might artificially inflate or deflate prices during crucial trading periods.
What This Means
For Indian traders and investors, these changes primarily focus on increasing market efficiency on expiry days. By shortening the transition periods and modifying pricing methodologies, SEBI aims to mitigate sharp price fluctuations witnessed during closing sessions. Additionally, removing the indicative index value during the CAS is meant to prevent misinterpretation of signals that could lead to erroneous trading decisions.
The proposed alterations also reflect an effort by SEBI to adapt to the evolving market dynamics, ensuring that the auction method used for price determination aligns with the industry’s needs, especially considering that derivatives trading remains active even during the closing hour. Greater transparency and improved order management practices can help encourage more stable trading conditions.
Frequently Asked Questions
What is the closing auction session (CAS)?
CAS is a mechanism introduced by SEBI to determine the settlement price for securities at the end of trading, allowing buy and sell orders to be matched to arrive at an equilibrium price.
Why is SEBI changing the settlement price methodologies for derivatives?
SEBI aims to improve market stability and reduce volatility during expiry days by implementing methodologies that more accurately reflect market activities in the pricing of derivatives.
How will the changes affect trading hours?
The proposed changes could extend trading hours for CAS stocks and derivatives, promoting greater liquidity by allowing trading until 3:45 PM for derivatives under one of the options being considered.
When can we expect these changes to take effect?
SEBI has invited public comments on these proposals until October 3, after which a timeline for implementation will be determined based on feedback from market participants.
