First CAS Manipulation found.
SEBI has passed an ex-parte interim order against an FPI and a local stockbroker, for what it calls prima facie manipulation of CAS on 13 August and wrongful gains of ₹3.67 crore.
What really happened?
It was Sensex weekly expiry. Inside the auction window the index moved 362 points in two seconds, then 405 points in 28 seconds.
1. Copthall Mauritius was 86.6% of the entire gross buy value in that auction.
Every order across all 30 Sensex stocks at exactly 3% above reference price, the maximum the band allows.
Then it cancelled ₹98 crore of them once the move had happened.
It held long calls and short puts on that expiry. Spent ₹57 lakh in the cash market, made ₹2.96 crore in derivatives.
2. Mansi Share and Stock Broking did the reverse. ₹145 crore of sell orders below reference price, holding the index down while it exited its long puts, then cancelled 99% of them in three seconds.
That cancellation alone moved the Sensex 233 points.
No single order breached a price band. 3% was the permitted limit and cancellation is allowed.
What SEBI has alleged is that the intent behind them, read with the derivatives position, made them manipulative.
SEBI caught it in six days and says CAS makes manipulation easier to detect than VWAP did. But has it also made it easier to manipulate?
5August 19, 2026 1.3K 3 2
