The New York Stock Exchange said an outage of more than three hours was caused by problems associated with a software upgrade on the exchange’s computers.
The NYSE said in a statement Thursday that the upgrade caused communication problems between its trading software and other systems, causing customers’ orders to not go through.
The problem became severe enough by late morning Wednesday that the exchange decided to suspend trading at 10:32 a.m. Central time so the problem could be addressed. Orders were canceled, trading software was restarted and backup units were brought online, the exchange said.
The exchange restarted trading at 2:10 p.m. Central time, 50 minutes before the end of regular market trading.
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Wednesday’s shutdown was a black eye for the NYSE, but ultimately it did not broadly affect Wednesday’s trading. The Nasdaq still operated normally, and several other exchanges, including Bats Global Markets, the Lenexa-based electronic market operator, were also available for investors to execute trades while the NYSE worked through its problems.
Trading also continued throughout the day on the electronic NYSE Arca market.
Bats posted its largest share of daily trading volume ever on Wednesday. Bats also surpassed the blunted NYSE volume for the day.
While the exchange was only open for 50 minutes in the afternoon, it was enough time for investors to close out their positions for the day.
The outage came at a time when traders had plenty of other things to worry about. There have been concerns about China’s plunging stock market and a logjam in talks between Greece and its creditors that has weighed on investors’ moods all week.
On Thursday, stocks recovered some of the ground as encouraging news from overseas pushed the U.S. market higher.
In China, frantic efforts by authorities to stop a monthlong rout in the country’s stock market met with some success. The Shanghai Composite surged after opening sharply lower.
In Europe, stocks soared on speculation that last-ditch talks between Greece and its creditors would produce an agreement, preventing a possible Greek debt default.
In the U.S., the Standard & Poor’s 500 index rose 4.63, or 0.2 percent, to 2,051.31. The Dow Jones industrial average rose 33.20, or 0.2 percent, to 17,548.62. The Nasdaq composite rose 12.64, or 0.3 percent, to 4,922.40.
Traders who ventured to other markets Wednesday mostly found their way back to the NYSE on Thursday, according to total trading volumes posted online by Bats. The NYSE led all markets with 24.1 percent of trading in U.S. stocks Thursday, followed by Bats with 20.6 percent and Nasdaq with 18.1 percent.
The Star’s Mark Davis contributed to this report.