SEBI’s allegations concern trading on August 13 during the closing auction, when official stock closing prices are set. It suspects Copthall Mauritius Investment Ltd and Mansi Share and Stock Broking Ltd influenced the BSE Sensex to benefit their own options positions.

The regulator has directed the two firms to return a combined ₹3.7 crore in alleged unlawful gains. The trading restrictions remain until the amount is paid and the investigation concludes. SEBI board member Kamlesh Chandra Varshney has sought a detailed examination of the transactions. Both firms have 21 days to reply and may request a personal hearing.

According to sources cited in the report, Copthall intends to seek explanations and further details from SEBI rather than immediately challenge the order in court. It is also weighing an internal audit to identify possible weaknesses in its compliance arrangements. Its technical-error defence is a planned response, not an established finding.

Copthall is a foreign portfolio investor that facilitates Indian investments for JPMorgan’s global clients. The restrictions do not cover JPMorgan India Pvt, a separately registered stockbroker and merchant banker. The case follows SEBI action against Jane Street Group last year and puts closing-auction trading under renewed scrutiny.