Mumbai, August 12: Retail stock market participants across India have observed a coordinated “No Trade Day” boycott on Wednesday, August 12 to protest the Securities and Exchange Board of India’s (SEBI) newly implemented Closing Auction Session (CAS) mechanism and elevated Securities Transaction Tax (STT) rates.
The boycott campaign has gained significant traction on social media, where day traders and influencers have urged peers to refrain from placing orders to highlight growing frustration over regulatory changes and end-of-day price volatility.
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Why Retail Traders Are Protesting CAS
SEBI introduced the Closing Auction Session on August 3, 2026, for roughly 200 stocks traded in the Futures & Options (F&O) segment. The new mechanism replaces the traditional 30-minute Volume Weighted Average Price (VWAP) calculation with a dedicated 15-minute call auction window between 3:15 PM and 3:30 PM to determine official closing prices.
Traders allege that the new auction system has created several structural issues for non-institutional market participants:
- Unusual Price Divergence: The auction mechanism has created sharp gaps between the 3:15 PM market price and the final 3:30 PM auction settlement price, resulting in unanticipated losses for intraday positions and automated trading strategies.
- Institutional Advantage: Retail groups argue that the call auction structure heavily favors large institutional players and high-frequency algorithms that can place large block orders during the order-entry window.
- Index Discrepancies: The transitional volatility caused temporary divergences in price movements between major benchmark indices such as the Nifty 50 and the Sensex.
Regulator’s Position
SEBI and market infrastructure experts maintain that the introduction of CAS brings Indian capital markets at par with major global exchanges in the U.S., Europe, and Asia.
The regulator stated that under the old VWAP system, large end-of-day institutional flows caused artificial volatility and tracking errors for global passive funds and exchange-traded funds (ETFs). SEBI expects the initial price swings to subside as market participants adapt to the auction process, liquidity deepens, and brokerages complete required technical upgrades.
