Capital Market Stocks Surge up to 4% as SEBI Weighs Rolling Back Closing Auction Rules for Derivatives

Shares of Indian exchanges, broking platforms, and capital market intermediaries witnessed sharp buying interest on Tuesday, climbing as much as 4% in morning trade. The rally followed reports that the Securities and Exchange Board of India (SEBI) is considering a partial rollback of its newly implemented Closing Auction Session (CAS) framework for derivatives pricing, potentially reverting to the volume-weighted average price (VWAP) mechanism for at least a year.

Market participants welcomed the prospect of regulatory relief, having grappled with sharp expiry-day price swings, erratic indicative index calculations, and reduced liquidity since the auction mechanism was rolled out on August 3, 2026.

Intermediaries and Exchanges Lead the Rally

Brokerage firms and exchange operators saw broad-based accumulation as volume worries eased across derivative trading desks.

Key Stock Movements in Early Trade:

• BSE Ltd: Jumped nearly 3.55% to ₹3,292.30, pushing its market capitalisation close to ₹1.35 lakh crore.
• Angel One Ltd: Gained close to 3.5% to hit an intraday high of ₹293.65.
• Motilal Oswal Financial Services Ltd: Rose more than 3.1% to touch ₹1,038.95.
• Billionbrains Garage Ventures Ltd (Groww): Added 2.25% to ₹191.25, supporting a valuation near ₹1.2 lakh crore.
• National Stock Exchange of India Ltd (NSE): Advanced over 2.11% to trade at ₹1,760, keeping its market capitalisation near ₹4.35 lakh crore.
• Nuvama Wealth Management: Rallied 1.85% to ₹1,855.

Why the CAS Mechanism Came Under Scrutiny

Under the framework initiated in August 2026, SEBI replaced the traditional 30-minute VWAP settlement methodology with a dedicated 20-minute closing auction session for stocks with active Futures & Options (F&O) contracts. While designed to mirror international price discovery standards seen in the United States and Hong Kong, the system led to unexpected distortions in Indian bourses.

Derivatives activity became hyper-concentrated in the narrow 10-minute order collection window between 3:20 PM and 3:30 PM. According to SEBI data, average traded value per minute on the NSE surged from ₹126.31 crore (during 3:00 PM to 3:30 PM in the pre-CAS period) to ₹189.82 crore under CAS. On the BSE, the average per-minute value surged from ₹141.48 crore to ₹288.94 crore over the same intervals.

The sharp concentration of institutional and algorithmic orders within minutes caused outsized fluctuations in underlying expiry settlements. SEBI also flagged instances of erratic pricing and manipulation during weekly contracts expiry, prompting the regulator to issue a consultation paper on September 12 to review operational rules.

Expected Regulatory Adjustments

According to sources cited in reports, the proposed tweaks will bifurcate cash equity settlement from derivatives settlement:

Key Changes Under Consideration:

• Derivatives Settlement Reversal: SEBI is likely to halt the use of CAS closing prices for settling F&O contracts for at least twelve months, reverting instead to the 30-minute continuous trading VWAP (3:00 PM to 3:30 PM).
• Cash Market Retention: The closing auction framework will continue to be utilised for underlying cash equities to determine official end-of-day closing prices.
• Indicative Index Halts: The regulator previously proposed halting the real-time dissemination of indicative index values during the 10-minute CAS window to prevent misleading price cues while stock auctions are still underway.

What This Means for Domestic Investors

The prospective policy tweak is viewed as a major sentiment booster for India’s active trading ecosystem. Retail traders and proprietary desks had faced challenges adjusting to order restrictions, frozen index displays between 3:15 PM and 3:35 PM, and sudden shifts in settlement equilibrium.

By decoupling derivative expiries from auction spikes, SEBI looks set to provide the market with predictable expiry dynamics, easing execution risks for broking firms and stabilising daily transaction turnover across the Indian capital markets.

Tags: SEBI BSE NSE Angel One Groww Capital Markets