In the high-profile NSE co-location case, regulator Sebi on Thursday exonerated nine current and former officials of the exchange, including ex-MD and CEO Ravi Narain, saying they cannot be held responsible for any misconduct or non-compliance in the so-called “dark-fibre issue”.

The former officials who have been absolved from the charges are the exchange’s senior vice-president (operations) R. Nandakumar, co-location head Jagdish Joshi and chief technology officers (CTO) N. Muralidharan and Ravi Apte.

The current officials of the exchange to br exonerated are its chief operating officer (trading) Mayur Sindhwad, CTO-projects Sankarson Banerjee, CTO-operations G. Shenoy and vice-president regulations Suprabhat Lala.

The order came after an investigation by the Securities and Exchange Board of India (Sebi) against several former and current NSE employees and stock brokers in the co-location matter.

It was alleged that certain stock brokers were permitted to avail themselves point-to-point (P2P) dark fibre connectivity from Sampark Infotainment Pvt Ltd, a non-empanelled service provider, and the connectivity provided by this company conferred a latency advantage to a few brokers which resulted in a substantial increase in their turnover during the period from April-August, 2015.

While granting permission to stockbrokers to establish P2P connectivity from its co-location facility with the help of Sampark, the NSE has been alleged to adopt a discriminatory approach towards a large number of other stock brokers, by allowing Sampark’s services to be availed by only a few selected stock brokers.

It has been alleged that the NSE has not acted in a fair and equitable manner while dealing with its members and these nine officials were allegedly employed at top positions of the exchange during the period.