The New York Stock Exchange (NYSE) has suspended trading on all shares for technical reasons.
The NYSE, the largest exchange in the world, said it would provide more details as soon as possible. All open orders would be cancelled, according to Reuters.
The Nasdaq index reported no technical issues and said it continues to trade NYSE-listed stocks.
The Wall Street Journal website is also experiencing technical problems.
“We’re currently experiencing a technical issue that we’re working to resolve as quickly as possible,” a NYSE spokeswoman said in a statement.
“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.”
US markets were down before the halt in trading, which started just after 11:30am ET, as a fall in Chinese markets added to concerns about its impact on global economic growth.
One trader on the NYSE floor, Mark Otto, of J Streicher & Co, told Reuters: “It’s under control. We’re just waiting for word. There’s no sign of panic at all.
“We’re waiting to hear word on if there’s going to be a reopening, and when it is or any more details.”