BSE Sensex drops 2,100 points in CAS (Bankex put spikes)
The BSE Sensex had a roller coaster Thursday, dropping a massive 2,100 points during the new Closing Auction Session (CAS) before settling at 76,152.86, down 0.55%.
In the chaos, a Bankex put option shot up nearly 4,000% in minutes and then crashed back to zero just as quickly.
It was one of those market moments that left X users mystified.
CAS thin institutional liquidity fuels volatility
CAS is India's fresh way of deciding closing prices, an auction-style system launched on August 3, 2026 to match global markets like Hong Kong and South Korea.
But with most regular traders sitting out and CAS liquidity largely dominated by institutions during this short session, there's not much trading happening (less than 1% of daily cash-market turnover).
That means even small trades can send prices swinging wildly.
While CAS aims to align Indian markets with global practices, it's also bringing some serious volatility, and mystified X users.