SEBI Chairman Tuhin Kanta Pandey confirmed that the Closing Auction Session (CAS) is a permanent fixture, while emphasizing the regulator's openness to refining the mechanism based on feedback.

  • The Closing Auction Session (CAS) mechanism is a permanent structural change in the market.
  • SEBI will soon release a consultation paper on the Securities Lending and Borrowing (SLB) mechanism.
  • The regulator is actively monitoring data to address teething problems and potential manipulation.

The Securities and Exchange Board of India (SEBI) has reaffirmed that the new Closing Auction Session (CAS) mechanism, designed to determine closing prices, is a permanent addition to the market microstructure. Speaking at the NISM campus in Navi Mumbai, SEBI Chairman Tuhin Kanta Pandey stated that while the system is here to stay, the regulator remains receptive to stakeholder feedback to address any operational constraints.

The transition to CAS marks a significant shift from the previous Volume-Weighted Average Price (VWAP) method. While the old system often led to tracking errors, the new CAS provides a single, unified price for trade execution. However, Pandey noted that some market participants are struggling to upgrade legacy systems that were built around the older VWAP-based processes.

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Why This Matters

BozokMedia analysis shows that this microstructural shift is critical for the growing segment of passive investing, which now constitutes 30% of the Indian market. For Foreign Portfolio Investors (FPIs), having a precise and transparent closing price is vital for managing large-scale portfolios and reducing settlement risks. This move aligns the Indian markets more closely with global best practices.

CAS is a major microstructure change; while initial teething problems are expected, it is essential for long-term market integrity.

In addition to CAS, the regulator is moving to strengthen the Securities Lending and Borrowing (SLB) framework. Pandey announced that a consultation paper on this mechanism will be issued shortly. He also addressed concerns regarding market manipulation, stating that SEBI is currently analyzing data and social media suggestions to ensure the objectives of the new framework are met without compromising indicative price accuracy.

Historical Background

Historically, Indian stock exchanges relied heavily on VWAP to determine closing prices. As trading volumes increased and algorithmic trading became dominant, the limitations of VWAP—specifically its susceptibility to price volatility near market close—became more apparent. The introduction of CAS is a direct response to the need for more robust price discovery mechanisms.

Did You Know?: Passive investing, including index funds and ETFs, now accounts for nearly 30% of the total market participation in India.

Frequently Asked Questions

1. What is the main difference between VWAP and CAS?
VWAP calculates an average price based on volume throughout a period, whereas CAS uses an auction mechanism to arrive at a single, definitive closing price.

2. Why is SEBI issuing a consultation paper on SLB?
To strengthen and stabilize the securities lending and borrowing mechanism, ensuring it supports market liquidity and stability.