S&P 500 Index didn't update after CBOE error

Investors were unable to see the level of the Standard & Poor's 500 Index for almost an hour today after a computer malfunction at the Chicago Board Options Exchange prevented the dissemination of updates.

"Everything appears to be running OK," said Al Greenberg, head CBOE floor trader at BNY Convergex Group LLC in Chicago. "We saw bad quotes floorwide, so orders that were on the book here in Chicago we couldn't find or link to other exchanges to be filled. There was a lot of concern."

The S&P 500 traded for 1,075.05 at 9:31 a.m. in New York. It didn't update again until 10:27 a.m., when it rose to 1,078.03, because of a technical error at the CBOE, according to data compiled by Bloomberg.

The CBOE, the largest U.S. options exchange, is the official publisher of the S&P 500, according to Dave Guarino, a spokesman for New York-based S&P.

While floor traders at the CBOE were able to "see the markets on our screens in the pit" during the outage, updates weren't being sent elsewhere, said Dan Deming, an options trader at Stutland Equities LLC at CBOE in Chicago.

CBOE "experienced systems difficulties" starting at 9:30 a.m. New York time, exchange spokeswoman Gail Osten said in an e-mailed statement. Business continued via "open outcry," with traders placing orders by voice, until the malfunction was resolved at about 10:25 a.m. "All systems are now working."

The CBOE Volatility Index, a gauge of options prices for the S&P 500, was also affected by the error.