22 August 2013 Last updated at 13:44 ET
The Nasdaq is the second largest stock exchange in the US
The Nasdaq exchange has suspended trading, citing a "technical issue".
The US exchange sent a message to traders saying that a problem distributing stock price quotes meant all trading would be suspended until further notice.
The US Securities and Exchange Commission said it was watching the situation.
Trading on the other US exchanges was uninterrupted, with the Dow Jones up 42 points at 14,940.
Nasdaq advised firms to route their trades elsewhere.
Trading was halted at 12:14 EDT (16:14 GMT).
The Nasdaq is the second largest stock exchange in the US, and the world's largest electronic stock market.
Listed on the exchange are high-tech stocks such as Google, Apple and Facebook.
Source: BBC News - Business http://www.bbc.co.uk/news/business-23803093#sa-ns_mchannel=rss&ns_source=PublicRSS20-sa
