SEBI Sensex CAS Order: The Securities and Exchange Board of India (SEBI) has passed an ex-parte interim order against Copthall Mauritius Investment Limited and Mansi Share and Stock Broking Private Limited over prima facie unusual and potentially manipulative trading activity during the Closing Auction Session (CAS) on the BSE Sensex on August 13, 2026.
The action follows SEBI’s examination of sharp movements in the Sensex during the 15:20 to 15:30 CAS. The regulator identified three substantial price spikes, including a 362.02-point jump in just two seconds, a 132.67-point rise in 12 seconds and a 405.08-point increase within 28 seconds.
August 13 was the weekly expiry day for Sensex options on BSE. The settlement price of those options was based on the Sensex closing price determined through the CAS.
SEBI Sensex CAS Order: Three sharp Sensex movements during CAS
According to the SEBI order, the Sensex reference price at 15:15 was 77,829.6. The CAS began at 15:20, while the closing price determined through the auction was 78,079.96, rounded to 78,080 for calculations.
The first sharp movement occurred between 15:20:41 and 15:20:43. During those two seconds, the Sensex Indicative Equilibrium Price (IEP) moved from 77,661.40 to 78,023.42, representing a rise of 362.02 points.
The second spike was recorded between 15:24:08 and 15:24:20. The IEP increased from 77,707.84 to 77,840.51, a gain of 132.67 points in 12 seconds.
The third movement came between 15:25:49 and 15:26:17. During the 28-second period, the Sensex IEP climbed from 77,787.94 to 78,193.02, an increase of 405.08 points.
SEBI also noted a general downward trajectory between 15:21:03 and 15:26:00, when the Sensex moved from 77,991.05 to 77,893.61. The regulator said this decline was intermittently interrupted by one of the sharp upward spikes.
SEBI Sensex CAS Order: Copthall placed aggressive buy orders
SEBI’s examination found that Copthall Mauritius Investment Limited accounted for 99.91 per cent of the buy-order value during the first spike, 96.09 per cent during the second and 85.21 per cent during the third.
The regulator said Copthall placed aggressive buy orders across Sensex constituents at prices close to 3 per cent above the reference price. SEBI observed that the buying appeared to influence the Sensex IEP higher.
Copthall subsequently cancelled buy orders worth about Rs 98.12 crore across 30 Sensex constituents.
The order also examined the relationship between the trading activity and the entities’ positions in Sensex options expiring on August 13. SEBI said the available evidence did not prima facie indicate that Copthall and Mansi acted in concert.
Mansi placed and cancelled large sell orders
SEBI found that Mansi Share and Stock Broking Private Limited placed aggressive sell orders across eight Sensex constituents following the initial upward movement.
Between 15:21:03 and 15:24:59, Mansi placed sell orders covering 12.65 lakh shares. Around 7.05 lakh shares were placed at prices 2.5 per cent below the reference price, while another 4.6 lakh shares were within 1 per cent below the reference price.
The entire 12.65 lakh-share quantity was subsequently cancelled between 15:26:02 and 15:26:05.
SEBI said Mansi’s orders pushed the Sensex IEP lower for a period of around 4 to 5 minutes, with the downward pressure ending after the sell orders were cancelled.
The regulator described the different order patterns of the two entities as prima facie highly unusual and said they required further examination alongside their possible positions in futures and options.
SEBI imposes interim restrictions
Under the ex-parte interim order, SEBI has restrained both entities from accessing the securities markets. For Mansi, the restriction applies to its proprietary trading account.
Both entities have also been prohibited from participating in the equity segment’s Call Auction Session, directly or indirectly, including placing, modifying or cancelling orders during the CAS, until further orders. For Mansi, this restriction also applies to its proprietary trading account.
SEBI has directed banks and depositories to restrict certain debits from the entities’ accounts and demat accounts without its permission, subject to the conditions specified in the order. Client-fund bank accounts of Mansi are excluded from the relevant debit restriction.
The order also directs registrars and transfer agents not to permit transfers or redemptions of securities, including mutual fund units, held by the noticees. The entities cannot dispose of or alienate their assets or properties without prior SEBI permission.
They have also been directed to provide a full inventory of their movable and immovable assets, bank accounts, demat accounts, securities holdings, mutual fund investments and interests in companies within 15 days of the order.
SEBI said any open positions in exchange-traded derivative contracts can be closed or squared off within three months from the date of the order or at the expiry of the contracts, whichever is earlier.
The regulator said a detailed investigation is required into possible violations by the noticees and other suspects. The prima facie observations in the interim order will not prejudice the further examination.
The noticees have 21 days from receiving the order to file their replies or objections and may request a personal hearing. SEBI also said the order is without prejudice to any further action under law, including possible penalties or directions.
