Trading resumed shortly after 11 a.m. Eastern Standard Time, Nasdaq officials said
"A software glitch affected the ability to execute trades" on two Nasdaq platforms, said Pat Campbell, the exchange's chief operating officer.
The breakdown affected SelectNet, a communications delivery system between market makers and the small order execution system, or SOES, through which broker dealers send small orders to each other, Campbell said.
The glitch did not affect stock quotes Campbell said, nor did it appear to have a major impact on the amount of shares changing hands.
"It was pretty close to the same kind of volume," he said.
At 9:41 EST when the systems broke down, close to 60 million shares had changed hands. At 10, about 100 million shares had changed hands. An hour later, volume stood near 200 million, Campbell said.
Campbell said the software that caused the problem was a product that was developed internally. This type of problem hasn't occurred before, he said.
The disruption occurred amid a surge into record territory. The Nasdaq Composite climbed 36 points, or 1.7 percent to 2329.
A February jobs report that showed growth just slightly above most forecasts catalyzed an explosive U.S. stock rally Friday, allowing the Dow Jones Industrial Average to crack into record territory.
Written By Stephanie O'Brien, CBS MarketWatch