Health-care companies led a broad slide in U.S. stocks Friday afternoon as increased fears over the spread of a deadly outbreak of coronavirus rattled markets.

The S&P 500-stock index had its worst day since early October, ending down nearly 1% to 3295. The U.S. stock market benchmark also snapped a two-week winning streak.

The blue-chip Dow Jones industrial average fell 170 points, or 0.6%, to 28,990, after dropping as much as 225 points Friday afternoon following news that a Chicago woman has become the second U.S. patient diagnosed with the new virus from China.

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Health authorities worldwide have been taking measures to contain and monitor the coronavirus outbreak. Authorities in France reported the first two cases in Europe on Friday.

"It really is a reaction to the widening nature of what's going on with the coronavirus," said Lisa Erickson, head of traditional investments at U.S. Bank Wealth Management. "People are concerned about, ultimately, the impact on Chinese growth and perhaps global growth."

Drugmaker Bristol-Myers Squibb led the slide in health-care stocks, shedding 4.2%. Health insurers also fell: UnitedHealth Group dropped 2.2%. Biotech darling Amgen lost 3.4%.

Banks and other financial sector companies also took heavy losses, with credit card issuers among the biggest decliners on assumptions that travel spending could suffer. Discover Financial Services tumbled 10.1% and Synchrony Financial slumped 9.8%.

Airlines and several other companies in the tourism industries fared poorly amid worries about the potential economic impact of the virus. United Airlines fell 5% and American Airlines dropped 5.6%. Cruise line operator Carnival fell 4.4%.

The price of U.S. crude oil fell 2.9%, dragging down energy stocks. National Oilwell Varco skidded 5%.

Utilities were holding on to a slight gain as investors shifted money into what are often considered safe-play, high-dividend stocks and U.S. government bonds.

The surge in bond-buying sent yields lower. The yield on the 10-year Treasury note fell to 1.67% from 1.74% late Thursday, a big move.

Investors continued to dig through the latest batch of company earnings reports, including strong results from chipmaker Intel and American Express. Next week is shaping up as the busiest week for earnings reports, with roughly 40% of the companies in the S&P 500 due to issue their results for the last three months of 2019.