SEBI Revises CAS Rules: Impact on Groww, BSE and NSE

SEBI Revises CAS Rules: What It Means for Groww (

), BSE and NSE SEBI has revised the Closing Auction Session (CAS) framework after receiving more than 20,000 comments from market participants. The changes aim to improve closing-price discovery, clarify order handling and reduce volatility around derivatives expiry. Capital-market stocks, including NSE, BSE, Groww and Angel One, came into focus following the announcement. What Has Changed? - The 10-minute CAS will operate from 3:30 pm to 3:40 pm on trading days. - Both market and limit orders can be entered between 3:31 pm and 3:36 pm. During the final four minutes, only limit orders will be accepted. - Expiring index derivatives will stop trading at 3:30 pm, while stock derivatives will remain open until 3:45 pm, including on expiry days. - Derivatives settlement prices on expiry days will use the VWAP of the underlying index or stock over the final 30 minutes of regular cash-market trading. - The post-close cash-market session will run from 3:50 pm to 4:00 pm. Most changes take effect from December 7, 2026, while provisions for transferring unexecuted limit and iceberg orders will apply from February 8, 2027. Jefferies believes the changes could benefit brokers such as Groww, while the earnings upside for exchanges may be limited now that premium turnover has recovered to pre-CAS levels. My View The revised framework could reduce uncertainty around expiry-day price movements and improve trading predictability. However, the impact will differ across exchanges and brokers. Investors should focus on whether the revised rules lead to sustainable trading volumes, improved market participation and better earnings visibility. A regulatory change can influence sentiment, but its long-term value depends on how it affects actual business performance.