New Delhi, August 19, 2026 (Yes Punjab News)
The Securities and Exchange Board of India (SEBI) has issued its first interim order alleging manipulation of trades during the Closing Auction Session (CAS), raising concerns over the potential misuse of the mechanism introduced on stock exchanges earlier this month.
The order relates to trading on August 13, the weekly expiry day for SENSEX derivative contracts. SEBI has named Copthall Mauritius Investment Ltd and Mansi Share and Stock Broking Pvt Ltd as noticees, alleging that they placed aggressive orders in the cash market to influence the SENSEX and benefit from their respective derivatives positions.
The CAS was introduced on August 3. It begins after normal cash-market trading ends at 3:15 p.m., with a reference price determined between 3:15 p.m. and 3:20 p.m. The auction runs from 3:20 p.m. to 3:30 p.m. to determine the closing prices of eligible stocks.
Since movements in SENSEX constituents during this period can significantly influence the index’s final closing level, sharp price changes can also affect the value of expiry-day options.
According to SEBI, the SENSEX reference price on August 13 was 77,829.60, while the index eventually closed at 78,080. The regulator identified three sharp upward movements during the auction, alongside a broader downward movement.
In the first episode, the SENSEX rose 362.02 points in around two seconds. A second spike lifted the index by 132.67 points in about 12 seconds, while a third saw it rise 405.08 points in 28 seconds.
SEBI alleged that Copthall created upward pressure by placing aggressive buy orders at the maximum permissible limit of 3 per cent above the reference price across SENSEX constituent stocks.
During the first spike, Copthall accounted for 99.91 per cent of the total buy-order value, amounting to Rs 66.57 crore. In the second episode, its share stood at 96.09 per cent of total buy orders worth Rs 126.59 crore. During the third episode, it placed buy orders worth Rs 98.12 crore.
The regulator noted that Copthall cancelled its latest buy orders at 3:26:21 p.m., alleging that the orders were therefore not placed with a genuine intention to acquire the underlying shares.
SEBI also alleged that Mansi Share and Stock Broking attempted to push the SENSEX in the opposite direction. The broker placed sell orders for 12.65 lakh shares across eight SENSEX constituents, with a total value of Rs 143.43 crore, at prices substantially below the reference price.
According to the regulator, 99.06 per cent of those sell orders were cancelled within seconds after downward pressure had been created on the index.
SEBI linked the alleged cash-market activity to the derivatives positions held by the two entities. Copthall had synthetic long positions through calls and puts at the 77,500, 78,000 and 78,500 strikes, while Mansi held net buy put positions at the 77,800, 77,900 and 78,000 strikes.
Based on its assessment, SEBI estimated that Copthall allegedly made wrongful gains of around Rs 2.96 crore, while Mansi allegedly gained Rs 71.65 lakh from the alleged activity.
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