By Rafael Nam and Abhirup Roy
MUMBAI (Reuters) - National Stock Exchange stunned investors on Friday when its chief executive Chitra Ramkrishna quit for "personal reasons", only weeks before the country's biggest bourse is due to kick off its own initial public offering.
A source familiar with NSE's operations told Reuters that Ramkrishna had clashed with some board members over the timing of the listing, saying she had favoured a slower timeline.
Reuters reported in May that the timing of the IPO had caused friction with some of NSE's foreign shareholders, who alleged the exchange's management ignored them and purged their views from minutes of meetings.
The exchange appointed a new chairman, Ashok Chawla, a former head of the Competition Commission of India, in May and in June said it would forge ahead with a domestic listing, reducing the tension with investors.
NSE's board had accepted Ramkrishna's resignation and J. Ravichandran, who is NSE President, had been appointed interim CEO with immediate effect, while the board starts the process of finding a new CEO, the exchange said in a statement on Friday.
"The Board, while accepting her request, appreciated her sterling contribution to the growth of the organisation over the long years that she had been associated with it," it added.
Ramkrishna, who was not immediately available for comment, was among a group of executives who in the early 1990s started NSE as a challenger to the more established BSE Ltd, then known as Bombay Stock Exchange.
The 53-year-old was appointed joint managing director of NSE in 2009 and promoted to CEO in 2013.
NSE is now India's largest bourse with average daily volumes of about 3.6 trillion rupees ($52.75 billion) in equity derivatives and 214 billion rupees in equities, dwarfing the volumes of its older rival.
Under Ramkrishna's tenure the NSE has continued to push into the more lucrative derivatives markets, launching a trading platform for bond futures in 2014.
However, it was also marked by the bitter feud with foreign shareholders over the timing of the listing and allegations that the exchange had provided unfair access to market data and trading systems - which exchange officials have long denied.
A panel gathered by capital markets regulator, Securities and Exchange Board of India, to look into those allegations had recommended in April the exchange needed to further examine the alleged ties.
SEBI and NSE have not officially commented on the status of that internal examination.
Shareholders said they were stunned by Ramkrishna's sudden resignation, and expressed concern about how it would now impact NSE's listing.
The NSE has not disclosed how much money it would seek to raise. State Bank of India in July sold a 5 percent stake in the exchange NSE for 9.11 billion rupees, valuing it at 182 billion rupees.
"Listing is a key event for companies and even for professionals," said Amit Jain, managing director of GTI Capital, a shareholder in NSE, who said he was shocked that Ramkrishna had decided to leave at this moment.
($1 = 68.2455 Indian rupees)
(Editing by Alexander Smith)