NYSE Site Showing Incorrect Equities Data After Arca Computer Malfunction

A malfunction caused NYSE Euronext (NYX)’s Arca platform to disseminate incorrect equity prices, spurring confusion among traders over the direction of some stocks today.

Some closing quotes from yesterday on the New York Stock Exchange website reflected the glitch, including the SPDR S&P 500 ETF Trust, which was listed today as rising from $127.43. The security tracks the Standard & Poor’s 500 Index, which fell 0.4 percent to 1,280.04 at 12:04 p.m. in New York.

“On Thursday Oct. 27 at 7:27:31 p.m., NYSE Arca erroneously replayed certain trades in the extended session without a .T condition,” the NYSE said today in an e-mailed statement, referring to a code that prevents a trade from being listed as the closing price. “We are working on removing these trades from the tape but in the meantime, participants are advised to use the 4 p.m. closing price instead of the 7:27 p.m. prices.”

NYSE Euronext sent a list of corrected closing prices with the affected securities today. Eric Ryan, a spokesman for NYSE Euronext, declined to comment beyond the statement.

“You have to double check all prices prior to trading,” Jamie Lissette, the founder of Hammerstone Group, wrote in an e- mail. His Westport, Connecticut-based firm operates online discussion forums for professional investors. “Some stocks are off by 5 points or more,” he wrote.

Bloomberg LP, the owner of Bloomberg News, provides live market data and analytics. Price information on the service today reflected the closing levels at 4 p.m.

To contact the reporter on this story: Whitney Kisling in New York at wkisling@bloomberg.net.

To contact the editor responsible for this story: Nick Baker at nbaker7@bloomberg.net.

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