Explained: The Sensex Manipulation Case Behind SEBI's Ban On A JPMorgan Entity

Market regulator SEBI has barred Copthall Mauritius Investment, an entity owned by JPMorgan Chase & Co., along with Mumbai-based Mansi Share and Stock Broking, from trading in the securities market.

An interim order issued late on Wednesday accused both firms of manipulating Sensex prices through a newly launched auction mechanism used to fix daily closing prices.

What Exactly Did SEBI Find?

SEBI's surveillance systems flagged unusual activity on August 13, a Thursday that also happened to be the weekly expiry day for Sensex derivative contracts. The Indicative Equilibrium Price of the index, a figure calculated during the new closing auction process, showed an abnormal spike that day. The Sensex recovered 113.61 points during the session, and options prices moved sharply as well. This prompted SEBI to examine trading activity on the BSE in detail.

SEBI's order noted that the Sensex reference price stood at 77,829.6 at 3:15 pm, just before the auction began. By the time the session closed, the index had settled at a closing price of 78,079.96, arrived at through the CAS mechanism based on its constituent stocks. Between these two points, the order flagged sudden and irregular jumps in the Indicative Equilibrium Price through the ten-minute window, as shown below.

SEBI's order explained that since the settlement price of Sensex options due for expiry that day was tied directly to the closing price determined through CAS, any distortion during this window carried a direct bearing on options payouts. The chart above shows three sharp price spikes along with one gradual decline during the auction session. These movements have been broken down in the table below.

According to the order, Copthall placed large buy orders across every stock in the Sensex, pricing them well above where the market stood at the time. SEBI said these orders were not placed with any real intention of buying shares, since a significant number were cancelled soon after. The regulator believes the purpose was to push up the Sensex closing value, which in turn would have boosted the value of Copthall's expiring options positions. SEBI estimated the resulting gain at ₹2.96 crore.

Mansi Share and Stock Broking is accused of doing the reverse. The firm allegedly placed large sell orders in eight Sensex stocks, priced below the market rate, which pulled the index down for about five minutes. SEBI said Mansi cancelled nearly all these orders once it had booked profits on its own options positions.

What Is CAS, And Why Was It Introduced?

The Closing Auction Session, or CAS, is a new method SEBI introduced through a circular dated January 16, 2026, with the framework taking effect from August 3. It applies to stocks that have derivative contracts linked to them and was rolled out in phases.

Under this system, normal trading in the covered stocks stops at 3:15 pm. Between 3:15 pm and 3:20 pm, exchanges calculate a reference price. The auction itself runs from 3:20 pm to 3:30 pm, though exchanges can end it randomly in the final two minutes of that window. During the auction, prices are allowed to move within 3% of the reference price in either direction. A final closing price is then fixed by 3:35 pm, based on the price at which the largest volume of shares can be matched.

This replaced the earlier system, where the closing price was simply the average of trades executed in the last half hour of the trading day. Regulators said the change was meant to bring Indian exchanges closer to practices already followed in markets such as China, Hong Kong, Taiwan and South Korea, which use similar auction based closing mechanisms.

SEBI has said the new system gives it a better ability to spot irregular trading compared with the earlier volume weighted average price method, and its surveillance team has been monitoring the auction session on a daily basis since launch.

Is The New System More Vulnerable To Manipulation?

Trading data since CAS went live shows that participation during the roughly ten-minute auction window has been thin and dominated largely by institutional investors. Volumes during this session have stayed below 1% of total daily cash market turnover, a fraction of what the earlier closing method typically recorded.

Because so few trades pass through this narrow window, even relatively small buy or sell orders can end up moving an index by a disproportionate amount, something market participants have flagged since the mechanism came into force.

What Action Has SEBI Taken In The JPMorgan Entity Case?

SEBI has ordered the impounding of ₹3.68 crore, roughly $384,324, combined across both Copthall Mauritius Investment and Mansi Share and Stock Broking. Both firms have been barred from trading in the securities market and are also prohibited from participating in future CAS sessions until the investigation is complete.

Copthall, which typically invests in Indian equities through block deals, can challenge the order before the Securities Appellate Tribunal. SEBI has invoked Regulations 3 and 4 of the PFUTP Regulations along with Section 12A of the SEBI Act to make its case that the trading pattern was prima facie manipulative.

What Does SEBI Need To Prove For The Charges To Stick?

Legal experts said the regulator's real challenge lies in proving intent behind the trades, not just their unusual nature.

Anshul Verma, Partner at SKV Law Offices, said SEBI cannot rely on the trades simply looking odd or profitable. It must show that the order placement and cancellations were deliberately timed to move the index's Indicative Equilibrium Price, and withdrawn in a manner inconsistent with any genuine trading strategy. He added that this is a harder case to build in algorithmic or high-frequency trading contexts, where fast order placement and high cancellation rates are also common in legitimate strategies such as arbitrage or market making.

Raheel Patel, Partner at Gandhi Law Associates, made a similar point, saying the bar is higher than merely flagging unusual trading. Rohit Jain, Managing Partner at Singhania & Co, resonated with this view, adding that large orders, cancellations and profitable derivatives positions count only as circumstantial evidence unless SEBI can connect them directly to a false price signal, while ruling out any credible business explanation for the trades.

Can Copthall And Mansi Challenge The Ban?

On whether SEBI followed proper process while passing an order without a prior hearing, Alay Razvi, Managing Partner at Accord Juris, explained that this power flows from Sections 11(4) and 11B of the SEBI Act. To use it, the regulator must show a serious threat to market integrity, genuine urgency and that advance notice would have defeated the purpose of the order. Jain agreed, adding that such powers are meant to be used sparingly and should be followed by a prompt hearing.

On what arguments the two firms could raise before the tribunal, Razvi said they may point out that the alleged gain of about ₹3.68 crore is relatively small compared to the impact of a complete market ban, and that a lighter measure, such as allowing trading against a deposit, could have been used instead. Jain cited similar past instances where the tribunal permitted conditional trading rather than an outright ban. Patel added that since SEBI's order does not allege the two firms acted in coordination, this could also support an argument that the restriction is disproportionate.

How Does The Reliance Industries Case Fit In?

The Supreme Court's May 29, 2026 ruling, which overturned SEBI's fraud findings against Reliance Industries in the 2007 Reliance Petroleum futures trading case, came up when experts were asked how it could apply to this dispute.

Patel said the ruling supports the argument that profitable or unusual-looking trades alone do not amount to fraud, and that SEBI will need to establish a clear link between the CAS orders, the cancellations, the index movement and the options gains, while ruling out any innocent explanation for the pattern.

Tushar Kumar, Advocate at the Supreme Court of India, said the ruling gives Copthall and Mansi a meaningful defence, though it does not amount to a free pass for aggressive trading. He explained that the court had drawn a clear line between ordinary regulatory violations and fraud, holding that where manipulation rests on circumstantial evidence, SEBI must meet a higher standard of proof.

According to Kumar, an unusual trading pattern combined with a profitable outcome is not enough by itself, even though SEBI is not required to show that a specific investor was misled. He added that the actual case would likely turn on details such as order size, timing, the probability of execution, cancellation behaviour and the underlying trading logic used by the firms.

What Happens If SEBI's Case Is Proven?

Patel said that if the allegations are established, SEBI could seek to recover more than the ₹3.68 crore already impounded, impose monetary penalties, and extend the trading restrictions. He added that criminal proceedings are not off the table, though they would need to meet a considerably higher legal threshold than a civil case.

Kumar said the impounded amount is only a temporary protective step and not a ceiling on what the firms might eventually be made to pay. He noted that SEBI currently attributes roughly ₹2.96 crore of the alleged gains to Copthall and ₹71.65 lakh to Mansi, figures that could increase if further violations surface during the investigation. He also pointed out that Section 15HA of the SEBI Act allows for penalties of up to ₹25 crore or three times the wrongful profit, whichever is higher, in cases of fraudulent trading practices. Kumar added that the proposed Securities Markets Code, 2025 is expected to ease penalties for minor procedural defaults while retaining jail terms for serious cases of market abuse, though this framework will not apply retrospectively to the trades from August 13.