The New York Stock Exchange (NYSE) resumed trading at about 3:10 p.m. Wednesday after a technical glitch halted trading at 11:30 a.m.

The NYSE announced it's back after more than three hours of being off-line with a tweet:

Speculation quickly made the rounds that the exchange may have been the subject of a cyberattack, but the NYSE said early on that it was their own technical issue, and not some malicious, outside actor.

"We're currently experiencing a technical issue that we're working to resolve as quickly as possible," a spokeswoman for the NYSE said in a statement after the exchange was shut down. "We will be providing further updates as soon as we can, and are doing our utmost to produce a swift resolution, communicate thoroughly and transparently, and ensure a timely and orderly market re-open."

All open orders would be cancelled, the NYSE also said. NYSE told CNBC it had no timetable on reopen when it first shut down, leaving traders hanging for much of the day. The issue did not affect the NYSE Arca and NYSE Amex/Arca Options. The Securities and Exchange Commission said in a statement "we are in contact with the NYSE and are closely monitoring the situation."

The NYSE's trouble came on the same day that all United Airlines flights were grounded due to a computer issue.

The Nasdaq reported no technical issues and said it continues to trade NYSE-listed stocks.