Update 3:15 p.m.: Trading on the New York Stock Exchange has resumed.
The New York Stock Exchange says a technical problem that has suspended trading since late morning is an internal technical issue and not the result of a security breach.
The exchange made the statement in a tweet on its official Twitter account. The trading halt is ongoing.
NYSE-listed stocks are still trading on other exchanges. The Nasdaq and other exchanges are unaffected by the outage.
Before trading was halted, U.S. indexes were lower as investors worried about China's ability to stem a stock market slide.
The Dow Jones industrial average was down more than 200 points.
European markets were broadly higher as talks continue on Greece's debt woes.
This segment aired on July 8, 2015.