The Chicago Mercantile Exchange restarted its Globex electronic trading platform at 20.45 GMT, after a five-hour outage at the height of trading Thursday forced a big shift in volume to open outcry pits.
The Chicago futures and options exchange says the failure was caused by problems with network switches that route data from trading firms to the Globex platform.
The breakdown disrupted trading in the E-Mini S&P 500 and E-Mini Nasdaq-100 futures, and also affected dealing in foreign currency futures. Stock index trading desks were forced to unwind orders being worked through the system when the breakdown occured.
The outage is the latest in a series of technical glitches to hit Globex and a huge embarrassment to the CME which has played up the benefits of electronic trading. Last week the Exchange reported that a record rise in electronic transaction volumes had contributed to a 25% revenue rise and a 40% increase in first quarter net income.
With Globex down, many firms switched orders to the CME dealing floor where the S&P 500 futures contract is still traded eyeball to eyeball in the pits.