The New York Stock Exchange had to shut down trading abruptly shortly before noon Wednesday over what officials said was a technical malfunction that froze computers on the market’s fabled trading floor.

One of the world’s biggest stock exchanges had seen shares trending down throughout the morning because of economic crises in Greece and China, but all trading halted at 11:32 a.m. as data on trades and prices apparently stopped coming into the traders’ computer screens. Nearly an hour later, the market was still down.

Many of the country’s biggest corporations, from Google and Apple to General Motors and General Electric, trade on the NYSE. NYSE officials said in a statement a “technical difficulty” shut down trading and technicians were working on a “swift resolution” of the problem. Trading in all securities listed on the market was halted.

NYSE New York Stock Exchange halts trading shut down

Officials at the NASDAQ said trading on its markets was proceeding normally, and trades on other U.S. markets appears to be functioning normally,and trades on other U.S. markets appears to be functioning normally. NYSE-issued stocks were also trading normally in other markets.

The stock market’s computer problems came just hours after United Airways had to ground all of its flights for several hours over another computer malfunction. United officials said an “issue with a router” caused the operational disruptions, and that it would take much of Wednesday to catch up for the delayed and cancelled flights.

NBC News, citing Justice Department officials, said officials had found no link between the United and NYSE incidents, nor was there any evidence at first blush of an attack by hackers.

Meanwhile, trading in shares was continuing on other exchanges, and the S&P 500 and other stock indexes were little changed from where they had been trading before the outage.