Stocks soared on the last trading day of January, led by big gains in technology companies after Microsoft turned in a strong quarter.
A bad start to 2016 for the stock market got even worse.
U.S. stocks posted steep losses on their first trading day of 2016. The Dow Jones Industrial Average plummeted 274 points, or 1.57 percent, to end the session.
US stocks are closing with sizable losses after a technical outage forced the New York Stock Exchange to halt trading for half the day.
Trading on the Nasdaq stock exchange is resuming after a three-hour halt caused by a technical glitch.
Other exchanges were operating normally Thursday, and stocks rose slightly.
The stock market is finishing its worst day since the financial crisis.