New CAS rules decoded: What Sebi’s revised framework means for stock market traders

What happened: Sebi revised its Closing Auction Session framework after trader backlash over unpredictable price moves, setting a 3:30 pm to 3:40 pm session with three phases and reverting derivatives expiry settlement to the VWAP method. Key numbers: CAS runs 3:30 pm to 3:40 pm; derivatives trade until 3:45 pm; order entry closes Why it matters: Jefferies says the revised framework should reduce expiry-day volatility, benefiting brokers whose orders remain below pre-CAS levels, though earnings upside for capital market stocks may be limited as premium turnover returns to pre-CAS levels.

Sebi revised its Closing Auction Session framework after trader backlash over unpredictable price moves, setting a 3:30 pm to 3:40 pm session with three phases and reverting derivatives expiry settlement to the VWAP method.

Jefferies says the revised framework should reduce expiry-day volatility, benefiting brokers whose orders remain below pre-CAS levels, though earnings upside for capital market stocks may be limited as premium turnover returns to pre-CAS levels.