‘No trade day…’: Day traders call for boycott against closing auction session
Traders have alleged that the new mechanism has led to a wide divergence between the two leading indices, Nifty and Sensex, as well as differences in the closing prices of some stocks, causing substantial losses for them.
- Aug 10, 2026,
- Updated Aug 10, 2026 11:49 AM IST
Day traders, spooked by the recently introduced Closing Auction Session (CAS), have started an online campaign to boycott trading in the stock market on August 12. They say the new system is working against them and in favour of large institutions, and have also raised objections to frequent rule changes by the regulator and high taxes.
Several social media posts called for a one-day protest.
One trader on X with nearly 1.5 lakh followers wrote, “No trade day on Aug 12. Against STT (securities transaction tax). Against CAS.” Another post said, “One day trading boycott against regulations and rising taxes impacting retail traders.”
MUST READ | Closing auction session: Key features, how it may address higher end-of-day volatility
Traders have also alleged that the new mechanism has led to a wide divergence between the two leading indices, Nifty and Sensex, as well as differences in the closing prices of some stocks, causing substantial losses for them.
The CAS was recently introduced to determine the closing price of about 200 stocks that are also traded in the derivatives segment of the exchanges. At present, the closing price of stocks in the equity cash segment is based on the Volume Weighted Average Price (VWAP) of trades executed during the last 30 minutes of the Continuous Trading Session (CTS).
Under that system, large institutional trades near the end of the session can disproportionately skew prices, while volatility can rise on index rebalancing days and derivative expiry, creating distortions for passive funds and arbitrage strategies.
DON'T MISS | Explained: Why Closing Auction Session is triggering sharp market swings
SEBI said it received feedback from global passive funds that trade Indian equities that they typically faced significantly higher end-of-day price volatility than investors in most other markets. According to the feedback, this could hurt the performance of mutual funds, passive funds and exchange-traded funds, as well as investment returns and the trading experience of retail investors.
The regulator also noted that because the Indian securities market ecosystem does not currently support execution at a single closing price, there was scope for index tracking differences among passive funds.
MUST READ | Why are Nifty and Sensex moving opposite? NSE explains Closing Auction Session
Based on its research and a study of practices in other major jurisdictions, SEBI said a closing auction session can provide a more stable and less volatile closing price than a VWAP-based method. The regulator said CAS is used in major global markets across the United States, Europe and Asia; gives all categories of market participants, investors and traders an equal opportunity to take part in price discovery; pools liquidity into a single auction; and helps provide a fair and transparent closing price.
Day traders, spooked by the recently introduced Closing Auction Session (CAS), have started an online campaign to boycott trading in the stock market on August 12. They say the new system is working against them and in favour of large institutions, and have also raised objections to frequent rule changes by the regulator and high taxes.
Several social media posts called for a one-day protest.
One trader on X with nearly 1.5 lakh followers wrote, “No trade day on Aug 12. Against STT (securities transaction tax). Against CAS.” Another post said, “One day trading boycott against regulations and rising taxes impacting retail traders.”
MUST READ | Closing auction session: Key features, how it may address higher end-of-day volatility
Traders have also alleged that the new mechanism has led to a wide divergence between the two leading indices, Nifty and Sensex, as well as differences in the closing prices of some stocks, causing substantial losses for them.
The CAS was recently introduced to determine the closing price of about 200 stocks that are also traded in the derivatives segment of the exchanges. At present, the closing price of stocks in the equity cash segment is based on the Volume Weighted Average Price (VWAP) of trades executed during the last 30 minutes of the Continuous Trading Session (CTS).
Under that system, large institutional trades near the end of the session can disproportionately skew prices, while volatility can rise on index rebalancing days and derivative expiry, creating distortions for passive funds and arbitrage strategies.
DON'T MISS | Explained: Why Closing Auction Session is triggering sharp market swings
SEBI said it received feedback from global passive funds that trade Indian equities that they typically faced significantly higher end-of-day price volatility than investors in most other markets. According to the feedback, this could hurt the performance of mutual funds, passive funds and exchange-traded funds, as well as investment returns and the trading experience of retail investors.
The regulator also noted that because the Indian securities market ecosystem does not currently support execution at a single closing price, there was scope for index tracking differences among passive funds.
MUST READ | Why are Nifty and Sensex moving opposite? NSE explains Closing Auction Session
Based on its research and a study of practices in other major jurisdictions, SEBI said a closing auction session can provide a more stable and less volatile closing price than a VWAP-based method. The regulator said CAS is used in major global markets across the United States, Europe and Asia; gives all categories of market participants, investors and traders an equal opportunity to take part in price discovery; pools liquidity into a single auction; and helps provide a fair and transparent closing price.