"The issue we are experiencing is an internal technical issue and is not the result of a cyber breach," NYSE said on Twitter. "We chose to suspend trading on NYSE to avoid problems arising from our technical issue."
The exchange, the leading US platform for trading equities, halted trade just after 1530 GMT (11:30 EST), freezing the buying and selling of the shares of many of the world's largest companies.
The outage came shortly after United Airlines grounded planes at US airports for an hour due for what it called a computer problem.
President Barack Obama had been briefed on the NYSE suspension, said White House spokesman Josh Earnest.
More From This Section
"There is no indication that malicious actors were involved," Earnest said.
Thomas Farley, president of the NYSE Group, told CNBC the exchange planned to reopen around 1845-1900 GMT to give an hour of trade before the close.
Farley said the technical issue appeared to be a "configuration problem" but he said it was "premature" to discuss the specific cause.
But stocks listed on the NYSE, which is owned by Intercontinental Exchange (ICE), continued to trade on other exchanges, including the Nasdaq and the BATS, the third largest US exchange.
"What's extremely interesting is that there was practically no change in stocks due to the glitch," Volokhine said.
"If this had happened 12 years ago, there would have been panic."
It was the second major US exchange outage sin nearly two years. The Nasdaq froze trade for three hours in August 2013 due to technical problems.
But the second-ranked exchange threw a barb at its rival. "Nasdaq systems are operating normally and are trading all symbols including Tape A (NYSE) securities," it said via Twitter.