CAS Manipulative Trade Case: SEBI Impounds Rs 3.68 Crore, Restrains Two Entities

On Wednesday, Indian equity benchmark indices traded lower, with the benchmark Nifty 50 index falling 76.60 points or 0.32 per cent to 24,078.30. Amid the market movement, the Securities and Exchange Board of India (SEBI) issued an ex-parte interim order in the matter of alleged manipulative trades during the Closing Auction Session (CAS) on the BSE Sensex weekly expiry of August 13, 2026.

The order concerns Copthall Mauritius Investment Limited and Mansi Share and Stock Broking Private Limited. Based on its preliminary examination, SEBI calculated total prima facie wrongful gains of Rs 3,67,80,773, comprising Rs 2,96,16,000 in the case of Copthall and Rs 71,64,773 in the case of Mansi.

What Happened During the Sensex CAS?

SEBI introduced the Closing Auction Session through a circular dated January 16, 2026, with the framework becoming effective from August 3, 2026. Under the mechanism, normal trading in covered cash-market securities stops at 3:15 pm, a reference price is calculated between 3:15 pm and 3:20 pm, and the CAS runs from 3:20 pm to 3:30 pm, subject to random closure between 3:28 pm and 3:30 pm. The permissible CAS price band is plus or minus 3 per cent of the reference price.

August 13 was the weekly expiry day for Sensex options. The Sensex reference price at 3:15 pm stood at 77,829.60, while the closing price determined through CAS was 78,079.96, rounded to 78,080 for calculations.

SEBI surveillance observed three sharp moves during the auction. The first saw the indicative Sensex equilibrium price jump 362.02 points in just two seconds, from 77,661.40 to 78,023.42. A second spike added 132.67 points in 12 seconds, while the third saw the index rise 405.08 points in 28 seconds, from 77,787.94 to 78,193.02.

SEBI Flags Copthall’s Aggressive Buy Orders

According to SEBI’s examination, Copthall placed large buy orders across Sensex constituents near the upper permissible CAS price limit.

During the first spike, total buy orders were worth about Rs 66.64 crore, of which Copthall alone accounted for approximately Rs 66.58 crore, or 99.91 per cent. Its 32 limit buy orders were spread across all Sensex constituents and were placed around 3 per cent above the reference price.

The pattern continued during the second spike. Copthall placed limit buy orders worth around Rs 126.59 crore, accounting for 96.09 per cent of the total limit buy order value of Rs 131.74 crore during that period. SEBI also noted substantial concentration from Copthall during another relevant period, when it accounted for around 85.21 per cent of buy-order value.

At 3:26:21 pm, Copthall simultaneously cancelled its latest buy orders worth around Rs 98.12 crore across all 30 Sensex constituents. SEBI observed that the aggressive buy orders had prima facie contributed to an upward movement in the Sensex IEP.

Earlier in the CAS, Copthall had cancelled 10,38,201 shares out of a gross buy order quantity of 31,66,651 shares, representing a cancellation rate of 32.79 per cent.

Mansi’s Sell Orders Came Under Scrutiny

SEBI separately examined Mansi Share and Stock Broking’s activity. Between 3:21:03 pm and 3:24:59 pm, Mansi placed aggressive sell orders aggregating 12.65 lakh shares across eight Sensex constituents. Around 7.05 lakh of these shares were placed at prices 2.5 per cent below the reference price.

The entire 12.65 lakh-share block was subsequently cancelled between 3:26:02 pm and 3:26:05 pm. SEBI observed that Mansi’s sell orders exerted downward pressure on the indicative Sensex level until their cancellation. The regulator estimated that the cancellation itself led to an immediate 232.96-point increase in the Sensex IEP, indicating that the sell orders had suppressed the index by at least that amount.

SEBI said Copthall and Mansi adopted opposite but highly aggressive price-impacting strategies. Importantly, however, the regulator stated that the evidence did not prima facie indicate that the two entities acted in concert.

Link Between CAS Trades and Sensex Options

SEBI also examined the entities’ expiry-day derivatives positions.

Copthall held net long call and net short put positions across the 77,500, 78,000 and 78,500 Sensex strikes. According to SEBI, such positions benefited from an upward movement in the index. The regulator therefore viewed the cash-market CAS activity and expiry-day option positions together.

For calculating the prima facie wrongful gain, SEBI considered 77,840 as the fair Sensex settlement level, based on the Nifty 50’s movement, against the actual Sensex settlement level of 78,080. On this basis, it calculated Copthall’s wrongful gain or avoided loss at Rs 2,96,16,000. SEBI noted that Copthall incurred an estimated cash-segment price variance of around Rs 57 lakh while generating the larger derivative benefit.

Mansi, meanwhile, held long positions in Sensex put options at the 77,800, 77,900 and 78,000 strikes. SEBI observed that during the period when the Sensex IEP was allegedly suppressed, Mansi squared off these put positions before they subsequently expired worthless at the final Sensex level of 78,080.

SEBI calculated Mansi’s prima facie wrongful gains at Rs 71,64,773. The regulator did not reduce this figure by the Rs 7,15,292 negative square-off difference from additional put trades executed during the same period.

SEBI Impounds Rs 3.68 Crore and Restrains Entities

In its August 19 order, SEBI directed that the Bank accounts of the two noticees be impounded to the extent of the alleged wrongful gains. Copthall has been directed to set aside Rs 2,96,16,000, while Mansi must set aside Rs 71,64,773, taking the total to Rs 3,67,80,773. The amounts are to be placed in fixed deposits with a lien marked in favour of SEBI.

Both entities have also been restrained from accessing the securities market and prohibited from participating directly or indirectly in CAS, including through placing, modifying or cancelling orders. In Mansi’s case, these restrictions apply to its proprietary trading account.

SEBI also restricted debits from the noticees’ bank and demat accounts, subject to specified exceptions, and directed that securities and Mutual Fund units held by them should not be transferred or redeemed. Mansi’s client-fund bank accounts are excluded from the debit restriction. The noticees have also been directed not to dispose of assets without SEBI’s prior permission and to submit a full inventory of their assets, bank accounts, demat accounts and investments within 15 days.

Existing exchange-traded derivative positions may be squared off within three months from the date of the order or at their expiry, whichever is earlier. SEBI also directed both noticees to cooperate with the continuing investigation.

The regulator said urgent directions were warranted because the noticees had also created positions in the upcoming August 20, 2026 Sensex weekly options, raising concerns over possible recurrence while the examination remained underway.

SEBI clarified that the findings in the interim order are prima facie and that a detailed investigation into the noticees and other suspects will continue. The two entities may submit their replies or objections within 21 days of receiving the order and may seek a personal hearing. The order was passed by SEBI Whole Time Member Kamlesh Chandra Varshney on August 19, 2026.
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Disclaimer: The article is for informational purposes only and not investment advice.