NEW YORK (USA TODAY) -- Nasdaq planned to reopen trading Thursday afternoon after trading in all Nasdaq-listed stocks and options was halted for more than two hours due to an unknown technical glitch.
Shortly before 2:30 p.m. EDT, Nasdaq announced that it intended to re-open trading at 3:25 p.m. EDT. All stock quotes had been cleared, according to the exchange, which also said customers who wished to cancel their orders may do so.
Customers who don't want to participate in the reopening should cancel their orders prior to the resumption of of trading, Nasdaq said.
The glitch struck shortly after noon East Coast time. Citing an issue involving electronic quote dissemination, the Nasdaq exchange announced at 12:14 p.m. it was "halting trading in all Tape C securities until further notice."
The exchange announced it had halted options trading at 12:28 p.m. and said firms needing assistance canceling orders should contact market operations.
Trading in all stocks listed on the New York Stock Exchange and the NYSEMKT exchange "continue business as usual," spokesman Rich Adamonis said earlier Tuesday afternoon.
"This is a very big problem. It's the flash freeze," says Sal Arnuk, a trader at Themis Trading in New Jersey.
The problems are connected with the Security Information Processor, a system that collects stock prices used by the public, Arnuk says. "This is a very big issue. The markets are broken."
John Nester, a Securities and Exchange Commission spokesman, said "we are monitoring the situation and are in close contact with the exchanges."
The trading glitch did not appear to be caused by a computer hacking incident, according to a federal law enforcement official who did not want to be named because he was not authorized to speak publicly on the matter.
There were no immediate signs of problems on other markets, said Michael Farr of Farr Miller & Washington, an investment management firm in Washington, D.C. "You're not seeing a breakdown in bond, gold not going through the roof. Right now the market seems to be taking it very much in stride."
"It's all going to hinge on the cause," said Farr. "If we find out this proes to be hacking or cyberterrorism, then you could see all three markets drop."
Traders were relieved that trading volume has been light, as that may reduce the impact ofthe outage. But the danger is how the system will react when all the cancelled orders are released when the system comes back up, Arnuk says. "It's almost unpredictable what will happen in the market," he says.
It's the latest black eye for the stock markets, which has been home of several trading problems. Investors are still vexed by the Flash Crash of May 6, 2010 when the value of the Dow Jones industrial average crashed more than 1,000 points over a period of about 15 minutes.
And it's another embarrassment for Nasdaq, which was widely panned for trading problems and delays with the initial public offering of social networking stock Facebook last year.