By:- Somil Mehta, Head of Retail Research, Mirae Asset Sharekhan
SEBI has revised its Closing Auction Session (CAS) rules to address concerns around sharp price movements on derivatives expiry days. From December 7, 2026, settlement prices for expiring derivatives will be calculated using the volume-weighted average price (VWAP) during the final 30 minutes of regular trading. The closing auction will be shortened to 10 minutes. These changes are expected to improve price discovery, reduce expiry-day volatility, and restore trader confidence. Higher trading activity could benefit brokerage firms through increased trading volumes and liquidity. However, the actual impact will depend on how market participants respond to the revised framework.
