From Financialexpress · Oliviya Kunjumon · · 1m 10s
SEBI updates CAS rules for F&O traders
SEBI's new CAS rules from Dec 7 could cut expiry-day volatility and boost brokers.
In brief
SEBI's new CAS rules from Dec 7 could cut expiry-day volatility and boost brokers. SEBI's revised Closing Auction Session rules, effective Dec 7, 2026, aim to reduce expiry-day volatility and benefit brokers more than exchanges. Originally reported by Financialexpress.
SEBI revises CAS rules
SEBI updates Closing Auction Session rules to reduce expiry-day volatility and benefit brokers more than exchanges.
“cas: sebi removes uncertainty; bigger +ve for brokers vs exchanges”
Key changes effective Dec 7
SEBI's revised framework takes effect on December 7, 2026, including new reference price calculations and shorter auction timing.
How brokers benefit
Jefferies sees brokers gaining from reduced volatility as order activity returns to pre-CAS levels.
New reference price method
SEBI uses volume-weighted average price of constituent stocks during continuous trading for index derivatives.
Auction timing adjustments
CAS timings shortened to 10 minutes with reference price calculation from 3:30 pm to 3:31 pm.
Brokers vs exchanges impact
Brokers may benefit more than exchanges as order activity remains below pre-CAS levels.
What investors should watch
Lower expiry-day volatility could improve broker activity, but actual impact depends on trading behavior.
Here's the gist
SEBI's revised Closing Auction Session rules, effective Dec 7, 2026, aim to reduce expiry-day volatility and benefit brokers more than exchanges.
