The CBI has detained Anand Subramanian, a former top official of the NSE.

Subramanian had also received notices from the central investigation agency.

Anand Subramanian, the former NSE group operating officer, was arrested late Thursday night by the CBI, days after he was questioned about his involvement at the country's main stock exchange. The central investigation agency has also issued notifications to Subramanian in connection with the investigation into anomalies at the NSE (National Stock Exchange).

In the course of the probe, emails exchanged between the NSE's former CEO Chitra Ramkrishna and a 'yoga' living in the Himalayas have garnered widespread notice. The CBI questioned Ramakrishna for 12 hours last week in the 'tick-by-tick' manipulation case, which involves the unfair transmission of information from the exchange's systems to those of stock brokers.

Earlier this month, market regulator Sebi (Securities and Exchange Board of India) fined Ramkrishna 3 crore for exchanging classified information via email with this 'yogi,' an unknown individual.

Several major decisions she made as NSE CEO between 2014 and 2016, according to a February 11 SEBI order, were impacted by her interactions with this anonymous individual.

The NSE eventually discovered that the email address in question was operated by Subramanian. He, too, was hit with a 2 crore fine.

Ramakrishna's predecessor, the NSE's previous MD and CEO Ravi Narayan, was also fined Rs 2 crore.

The CBI had issued watch circulars against all three of them in order to prevent them from fleeing the country.

In 2018, the CBI launched a case against stock broker Sanjay Gupta, the owner and promoter of Delhi-based OPG Securities Pvt Ltd, for allegedly profiting from early access to the stock market.

"It was alleged that the owner and promoter of such private company conspired with unknown NSE employees to exploit the NSE's server architecture." It was also claimed that anonymous NSE, Mumbai personnel gave said company unfair access to the co-location facility between 2010 and 2012, allowing it to login first to the stock exchange's exchange server, which aided in obtaining the data.