A telecoms outage shut all trading on India's National Stock Exchange for nearly four hours on Wednesday, leaving investors in the dark ahead of a monthly derivative contract expiry and forcing bourses to extend trading hours after it reopened.
The NSE, headquartered in India's financial capital Mumbai, is the world's largest derivatives bourse by volume and the third-largest stock exchange globally in terms of the number of equity trades, according to its annual report.
Telecom disruptions forced the exchange to halt trading earlier in the day, resuming with the NSE Nifty 50 Index gaining 0.39% by 1008 GMT. The stock exchange did not specify the names of the telecom carriers.
The BSE and the NSE said equity and equity derivatives markets would remain open until 1130 GMT.
The glitch frustrated brokers, who demanded better guidelines and longer hours to to be able to square off their trades.
"I can't recall trading hours having been extended like this in the past decade. The move will be welcomed as people were completely stuck ahead of the derivatives expiry," said Ajit Mishra, vice-president, research at Religare Broking.
"Participants, especially derivatives traders, should now be able to square off or rollover their positions rather than leave it to the last day of expiry."
BSE's daily turnover — the total value of shares traded — reached nearly 400 billion rupees ($5.5 billion) by 1100 GMT, almost nine times the turnover in the previous session and about 7.5 times the average daily turnover, exchange data showed.
The NSE handled volumes worth 925.38 billion rupees ($12.78 billion) on an average in the financial year ending March, according to its annual report. It handled currency derivatives worth 198.35 billion rupees daily during the same period.
The stock exchange had faced a similar systems glitch in 2017 that led to a five-hour-long shutdown, prompting the market regulator to call for a review of the bourse's contingency plans.
Market regulator Securities and Exchange Board of India (SEBI) did not respond to Reuters' request for a comment on the NSE trading halt.