Ashish kumar Chauhan on Tuesday assumed charge as managing director and chief executive officer of the National Stock Exchange (NSE), a spokesperson of the exchange said. Chauhan earlier resigned as Managing Director and CEO of Bombay Stock Exchange and was relieved of his roles and responsibilities at the exchange from Monday. Bombay Stock Exchange, which has already begun the hunt for a new chief, said an executive management over committee of the exchange will be running its affairs till the appointment of the new MD and CEO. "Chauhan has taken charge as MD and CEO of NSE from today," a spokesperson of the exchange said. At NSE, Chauhan faces an uphill task of guiding the bourse bogged down by governance lapses, a co-location scam, technical glitches and a phone-tapping probe. At NSE, Chauhan faces an uphill task of guiding the stock exchange bogged down by governance lapses, a co-location scam, technical glitches and a phone-tapping probe. Besides, he will need to steer the long-pending initial public offer of the NSE. The NSE's public issue was derailed after the exchange got embroiled in the co-location controversy, where certain brokers were allegedly given unfair access to the exchange data feeds other members. At BSE, Chauhan is credited with reviving its revenues, helping it become the world's fastest exchange with 6 micro-seconds response time. Sebi notifies regulatory framework for social stock exchange FPIs return, invest Rs 1,100 cr in July so far Market falls, Top Stocks to buy today