The CBI issued lookout notices against NSE’s former CEO Ravi Narain and its former chief operating officer Anand Subramanian on Friday.

The tax raids on the Mumbai and Chennai residences of Ramakrishna and Subramanian continued for the second day.

A senior I-T department official said that financial transactions of Subramanian’s wife Sunitha Anand, a former NSE official, were also being investigated. It is not immediately clear if Narain and Subramanian have fled the country or are still in India. The CBI is also learnt to be investigating other unnamed NSE officials to gather evidence on allegations that some brokers got preferential access through the co-location facility at the stock exchange.

In this case, CBI had booked owner and promoter of Delhi-based OPG Securities Sanjay Gupta and others in connection with the alleged abuse of NSE co-location facility. The agecy is probing other officials of market regulator Sebi.

The regulator found that Ramakrishna shared sensitive information pertaining to financials, appraisals, increments and strategy with an unknown person, who is also referred to as the “Siddha Purush” by Ramakrishna.