Shares of airlines plunged and industrial, financial and energy stocks also fell sharply. Worry about long-term growth also pushed the yield on 10-year United States Treasury notes to a new low. Because of their relative safety, government bonds are in high demand during bouts of panic over the economy.

After markets closed on Thursday, Starbucks warned that its quarterly same-store sales in China, where it has a huge presence, would fall 50 percent compared to last year, resulting in a $400 million to $430 million hit to its revenue forecast.

News about the coronavirus’s spread has been relentless: A cruise ship being held off the coast of San Francisco has suspected links to two coronavirus cases, one of them fatal. The governor of California declared a state of emergency on Wednesday, and 18 states have infected patients.

Around the world, more than 90,000 cases and 3,000 deaths have been reported.

The jump in the number of cases in the United States has crystallized expectations that the crisis will last longer than earlier predictions suggested. And without the kind of full-court-press efforts that China staged to guard against the virus’s spread, some analysts worried that infections could expand widely.

Economists at the Institute of International Finance slashed their outlook for the global economy on Thursday, downgrading their 2020 forecast for the growth in the United States to 1.3 percent that in China to below 4 percent. The revisions could “conceivably” take global growth to 1 percent, the weakest since 2009, said the chief economist, Robin Brooks, and down from 2.6 percent last year.