Trading on the New York Stock Exchange resumed at mid-afternoon Wednesday after being halted for more than three-and-a-half hours by a technical issue.
Officials provided few details on the problem that they said caused the suspension of trading from 11:32 a.m. until about 3:10 p.m. ET. Earlier, the NYSE took to Twitter to assure the public that the shutdown was not caused by a cyberattack, a message that was echoed by the Obama administration.
"It's not a good day. I don't' feel good for our customers who are having to deal with the fallout," NYSE President Thomas Farley told CNBC after trading resumed.
He indicated the problem was likely related to an earlier problem that had been deemed fixed.
Just after 8 a.m. ET on Wednesday morning, the NYSE put out an alert about "a reported issue with a gateway connection" affecting certain symbols. It issued a notice at 10:37 a.m. ET that the problem was resolved.
"We opened the market as usual. All the NYSE-listed stocks opened without incident. Around mid-morning, we started to see some concerns about the way trading was occurring. Customers weren't getting all of the messages back that you otherwise expect," Farley said.
Two U.S. officials told NBC News there was no indication the NYSE shutdown was related to the computer issue that temporarily grounded all United Airlines flights on Wednesday morning. They also said there was no indication of a cyberattack.
Separately White House Press Secretary Josh Earnest said, "There is no indication that there are malicious actors involved."
President Barack Obama was briefed on the NYSE problems and the White House, Treasury Department, Securities and Exchange Commission and FBI all said there were monitoring the situation.
Investors were able to continue trading in NYSE-listed stocks during the shutdown as orders were routed to other exchanges.
Trader Mark Otto of J. Streicher & Co in New York told Reuters from the NYSE floor that the mood was calm despite the unexpected shutdown.
"It's under control. We're just waiting for word. There's no sign of panic at all," he said.
The NYSE said all open orders before the halt, including market on close, limit on close and closing offset, were canceled. The issue seemed to be limited to the main NYSE exchange and the NYSE MKT exchange for small-cap stocks. It said it did not affect the NYSE Arca and NYSE Amex/Arca Options.
The Nasdaq reported no technical issues and said it continued to trade NYSE-listed stocks.
The NYSE is owned by Intercontinental Exchange, which owns 11 exchanges.
An extended interruption of trading on the exchange due to a technical issue "has little precedent," the New York Times reported. The NYSE website lists seven closures since the founding of its predecessor exchange in 1817 related to world-changing events, including the assassination of President Abraham Lincoln and the terrorist attacks on Sept. 11, 2001.