All trading on the Nasdaq market was halted for more than two hours on Thursday due to a glitch in a system used to disseminate trading information.
First signs of a problem were seen at 10:57 a.m. EDT (14:57 GMT) when "momentary interruptions in quote dissemination" hit a system that pools data from exchanges that trade Nasdaq securities. Those problems lasted for six minutes before the system returned to normal operation, according to a market status message issued by the exchange.
But roughly an hour later, Nasdaq said there were problems with submission of quotes to the same system. As a result, Nasdaq halted trading at 12:14 p.m. EDT and the options market followed suit at 12:20 p.m. EDT.
The market was due to resume at 2:30 p.m. EDT with a staged opening that would see full trading of all stocks from 3:10 p.m. EDT.
Details on the cause of the problem were not immediately available.
Nasdaq operates one of the two top stock exchanges in the U.S. It is particularly popular with tech companies and the halt affected almost all trading of stocks in Microsoft, Apple and Google, among others.
At the time of the trading halt, the market had been having a quiet day. The Nasdaq composite index was showing a rise of just under 1 percent and was at 3631.17 points.
The last time the same system suffered a major problem was on April 5, 2012, when opening price data for stocks with symbols from M through R was not disseminated for an hour and 20 minutes.
Martyn Williams covers mobile telecoms, Silicon Valley and general technology breaking news for The IDG News Service. Follow Martyn on Twitter at @martyn_williams. Martyn's e-mail address is firstname.lastname@example.org