Monthly Expiry shock: Did CAS fail its biggest test after Sensex loses 2,000 points in 6 minutes?

The Sensex plunged about 2,000 points in roughly 6 minutes during the first monthly derivatives expiry under SEBI's new Closing Auction Session (CAS) framework, exposing structural vulnerabilities. Thinner auction volumes from reduced proprietary and high-frequency trader participation amplified price swings, while arbitrage opportunities narrowed. SEBI, which recently barred a JPMorgan Chase unit from the market for alleged auction manipulation, is reviewing deformities in CAS implementation even as Chairman Tuhin Kanta Pandey said the system is here to stay.