Market regulator orders ₹3.68 crore in alleged wrongful gains to be impounded after examining trading activity during the BSE Sensex closing auction session a few days ago.
The Securities and Exchange Board of India (SEBI) has taken interim action against Copthall Mauritius Investment Limited and Mansi Share and Stock Broking Private Limited over alleged manipulation during the Closing Auction Session (CAS) of the BSE Sensex on August 13, 2026.
In an ex-parte interim order issued on August 19, SEBI barred the two entities from accessing the securities market and directed that a combined ₹3.68 crore in alleged wrongful gains be impounded. This action comes only six days after the trades under scrutiny, highlighting the regulator’s focus on closely monitoring the newly introduced auction mechanism.
More on happenings during the closing auction session.
The trades took place during the Sensex weekly expiry, when movements in index-linked derivatives can significantly impact market participants. SEBI’s preliminary findings indicate that trading activity by the two entities affected price discovery during the Closing Auction Session. The regulator has alleged that Copthall Mauritius and Mansi Share adopted trading strategies that influenced prices during the crucial closing period. Reuters reported that SEBI has not, at this stage, found evidence that the two entities colluded.
The Closing Auction Session was introduced as part of a revised market mechanism designed to improve price discovery at the end of the trading day. It became operational from August 3, 2026.
Alleged gains of ₹ 3.68 crore, as per reports.
According to SEBI’s order, the regulator calculated alleged wrongful gains of approximately ₹2.96 crore for Copthall Mauritius and ₹71.65 lakh for Mansi Share and Stock Broking. The combined amount comes to about ₹3.68 crore. The regulator has also restricted the entities from accessing the securities markets while the proceedings continue. The measures are interim in nature and follow SEBI’s preliminary assessment of the trading activity.
The case comes at an early stage of the Closing Auction Session’s implementation and places greater attention on how market participants operate within the new framework. SEBI’s action signals that trading behaviour during expiry-day sessions, particularly when it can influence benchmark prices, will remain under scrutiny. The regulator’s investigation and subsequent proceedings will determine the final findings and any further action.
For investors, the episode underlines the importance of transparent price discovery and orderly trading, particularly during periods when derivatives expiry can amplify market sensitivity.
