New Delhi: Markets regulator Sebi and stock exchanges are looking into possible manipulation in equity and derivatives trade of some public sector banks (PSBs) in the wake of circulation of a fake letter purportedly for misleading the investors.

The fake notice bearing the regulator's logo and purportedly addressed to National Stock Exchange (NSE) was circulated on various WhatsApp groups and other social media platforms on February 21.

It apparently sought to mislead the market community in the wake of Rs 11,400-crore PNB scam by suggesting that Sebi was seeking details of futures and options data of all brokers and investors in various PSBs shares.

While the purported letter was soon found to be fake, the regulator and the exchanges are looking into trade details of various bank stocks to ascertain whether any manipulative activities took place, officials said.

Details would be also sought from telecom and internet operators, if required.

A day after the circulation of the letter, NSE clarified that Sebi did not issue any letter and the exchange did not receive any such directive.

Further, the exchange requested trading members to advise their clients to remain cautious on such unsolicited letter being circulated by unregistered and unauthorised entities.

"It is clarified by Sebi that no such letter is issued and NSE has not received any such letter from Sebi," the exchange noted.

As per the fake letter, Sebi had asked NSE to furnish futures and options data of all institutions, mutual funds, brokers and clients, who are keeping their futures position open at the end of the settlement- on February 22 of PSU bank futures contracts.

On February 14, PNB disclosed a Rs 11,400-crore (USD 1.77 billion) worth of fraud involving jewellers Nirav Modi and Mehul Choksi and their group firms.