mumbai a flash crash on the national stock exchange nse on friday morning due to erroneous trades by a dealer in 59 frontline stocks pulled the nse50 nifty index down 155 to 4888 raising questions about the robustness of the bourses software and leaving the exchange redfaced on the eve of a visit by the finance minister to the city it recovered at the end of days trade to close at 5747 down 41 while the sensex closed 120 points down at 18938 although nse suspended emkay global financial services the broking house where the trades had originated the incident invited severe criticism from market players about why the trading was not automatically stopped by the exchange given sebis rules that stipulates a circuit filter should kick in when the index goes up or down 10 in this case the trading was stopped when the index went down 155 which also triggered stop losses for several investors thus aggravating losses for no fault of theirs the flash crash also prompted sebi to start a preliminary investigation into the whole affair ravi varanasi head business development nse was quoted in a statement saying that the circuit filter was triggered at 10 and the cash market was stopped but the orders that were already in the system were executed in the next few seconds fridays session had started on a positive note with the nifty up about 30 points then between 950 am and 952am large chunks of several frontline stocks that included ril infosys icici bank sbi tcs and almost all the 50 nifty constituents were sold at prices which were about 20 lower than the previous closes this led to a 899point fall in nifty within a few minutes although as per nses september 28 circular trading should have been halted as soon as it crossed 570 points on the bse trading continued undisrupted and a statement from the exchange soon after the nse incident said that the market at bse was working fine and trading members are informed that there are no issues technical or otherwise at bse some marketmen are not buying into nses views they questioned that if the cash market was stopped how was it possible to execute orders even in a market which is shut 570 points becoming 900 in intraday trade which is around 16 is unacceptable unexplainable and cannot be tolerated when the circuit is at 10 said arun kejriwal director kris an investment advisory firm pointing at some of the recent system glitches at nse in april and may this year kejriwal said that such failures show something may be amiss at the leading bourse an enquiry of the highest order must be started by sebi and the finance ministry immediately he said market players also questioned nses decision to resume trading within 15 minutes after the shut down due to circuit breaker a june 2001 sebi circular stipulated that if trading is halted due to a 10 circuit breaker either