All trading on the New York Stock Exchange is halted Wednesday for unknown reasons. Trading still going on the Nasdaq.

Technical issues are blamed for the systems on the NYSE to shut down. Such outages are extremely rare in U.S. markets.

Traders on the NYSE floor were standing around looking at blank trading terminals where no bid or offers were being exchanged.

In a statement, the NYSE says: “We’re currently experiencing a technical issue we’re working to resolve as quickly as possible.”

The outage at the NYSE comes curiously the same day when a technical glitch halted United Airlines flights around the country for roughly two hours.