Stocks fell on Friday after the second U.S. case of the deadly coronavirus was confirmed, stoking concerns over the sickness' impact on the global economy.

The Dow Jones Industrial Average closed down 170.36 points, or 0.6%, at 28,989.73 after jumping more than 100 points earlier in the day. Friday also marked the Dow's first close below 29,000 since Jan. 14.

The 30-stock average briefly fell more than 300 points before recovering some of those losses as Boeing shares turned around. The S&P 500 fell 0.9% to 3,295.47, for its worst loss of the young year. The Nasdaq Composite ended the day 0.9% lower at 9,314.91.

"You could see going into the weekend the 10-year Treasury yield is down, gold is higher, the market is in a text book defensive state," said Quincy Krosby, chief market strategist at Prudential Financial. "We had a market that was poised for a bout of profit-taking and this is it."

On Friday, the Centers for Disease Control and Prevention said a Chicago resident who traveled to Wuhan — the Chinese city where the coronavirus originated — in December was diagnosed with the sickness.

U.S. Senator John Barrasso later said the CDC told lawmakers they are about to confirm a third case of the Wuhan virus in the U.S. "It looks like have two documented cases in the US, it looks like third may be confirmed as well."

Shares of United Airlines and American both fell more than 5%. Las Vegas Sands and Wynn Resorts also dropped more than 3% each.

Treasury yields fell, pushing bank shares lower. The benchmark 10-year yield dipped below 1.7%. JPMorgan Chase, Citigroup and Bank of America all traded more than 1.5% lower.