National Stock Exchange Vice Chairman Ravi Narain has resigned from the board, Mint reported on Friday. Narain is believed to have sent his resignation letter to NSE Chairman Ashok Chawla on Monday night, according to The Economic Times. The NSE is being probed by the Securities and Exchange Board of India over allegations that they gave preferential access to certain brokers to its servers.

The market regulator had recently issued show-cause notices to Narain, former Chief Executive Officer Chitra Ramakrishna and other NSE officials in connection with the investigation. Ramakrishna had resigned from her post as the the CEO and managing director at the exchange in December 2016.

The alleged violations took place between 2012 and 2014 when Narain was the chief executive officer and managing director of NSE. He is also one of the founding members of the exchange.