The February market rout deepened today as investors braced for the coronavirus to slow business activity and depress corporate earnings. The Dow industrials tumbled 1,190.95 points, or 4.4%, to 25766.64, bringing its slide this week to more than 3,200 points. The S&P declined 4.4%, extending its six-day decline to more than 10%—the fastest slide of that magnitude off a recent all-time high on record. The S&P 500 and the Nasdaq Composite notched their largest one-day percentage declines since August 2011. All three major U.S. indexes posted their biggest one-day point drops ever.

Commodities from oil to industrial metals also dropped today​. U.S. crude-oil futures slid 3.4% to $47.09 a barrel on the New York Mercantile Exchange. Prices are now 29% below a peak hit early this year. Brent crude closed down 2.3% to $52.18 a barrel on the Intercontinental Exchange. Saudi Arabia is slashing crude exports to China as demand weakens.

A U.S. coronavirus outbreak would trigger temporary but widespread disruptions of daily life and business activity, posing a new risk to the nation's longest economic expansion on record. Some U.S. companies said they could lose as much as half their annual revenue from China if the coronavirus epidemic extends through the summer. In Europe, investors are pulling out of Italian sovereign debt and heading for the safety offered by countries such as Germany and France.

• Among the best performers in the market's rout were Chinese stocks.
   
• Investors have dramatically reassessed the chances that the Fed will lower interest rates as soon as next month.
   
• 📞 On Call With WSJ: Register here for a conference call Friday at noon EST with Wall Street Journal editors and reporters on how global markets are reacting to the latest virus news.

More than 82,000 people have been infected by the virus globally. The death toll stands at more than 2,800. U.S. authorities said that a patient in California might be the first U.S. coronavirus case diagnosed without a clear explanation about how the disease was transmitted. Federal officials are ramping up testing after that case. 

President Trump put Vice President Mike Pence in charge of federal response efforts. Mr. Pence reiterated today that risk from the coronavirus remains low, but added: "We're ready—we're ready for anything." Senate Majority Leader Mitch McConnell (R., Ky.) called on lawmakers to pass legislation funding a response to the disease within the next two weeks. A final spending figure is expected between $4 billion and $8 billion.

South Korean soldiers sprayed disinfectant on a street in Daegu on Thursday. PHOTO: LEE MOO-RYUL/ASSOCIATED PRESS

In South Korea, government data indicated the virus outbreak there is now spreading faster than in China, where the virus first emerged. Some governments in Asia are wielding fines and jail terms to punish those accused of misleading investigators or flouting quarantine orders. Japan asked all schools in the country to shut for a month.

Italy's number of confirmed cases leapt to 650, but governments across the EU have so far declined to reinstate border checks or take other measures to isolate the country. Iran today reported 106 new infections, as faith-based travel in the Middle East emerged as a dangerous new risk in the spread of the virus. Saudi Arabia temporarily barred visitors arriving for religious pilgrimages.

• Epidemiologists love studying the Olympics: There are few places better at breeding illness. Now the Tokyo Games might be in trouble.
   
• Colleges and universities are canceling study-abroad trips.

Businesses are scrambling to respond to the outbreak and are already seeing its impact.

A closed Starbucks store in Shanghai, China, on Feb. 7. PHOTO: QILAI SHEN/BLOOMBERG NEWS

Banks with heavy exposure to Europe and Asia have warned their profits could be hit, and the auto industry braced for supply-chain disruptions. Starbucks said it had reopened hundreds of its China stores that had been closed in response to the outbreak. But other industries are reeling, such as toy companies, which are delaying product launches and struggling to fill orders after the epidemic closed or hindered factories in China.

Hollywood has already been forced to postpone several prominent films' release in China, and maritime operators are facing their biggest challenge since the 2009 financial crisis. Disruptions are likely to prolong a continuing slump in U.S. freight transport. Facebook said it had canceled its annual developer conference in California, scheduled for May. 

What We Know About the Coronavirus So Far, and How to Prepare Yourself

A man reaches for a mask at a Home Depot in Los Angeles. PHOTO: FREDERIC J. BROWN/AGENCE FRANCE-PRESSE/GETTY IMAGES

Increased travel and trade over the past couple of decades have significantly accelerated the risk of global spread of disease. Yet how big an impact the virus ultimately has depends on how transmissible and deadly it turns out to be, which isn't yet fully understood. The outbreaks in Italy, South Korea and Iran all started with a few cases and expanded quickly, suggesting that many mild cases contributed unseen to the spread.

The virus, called Severe Acute Respiratory Syndrome Coronavirus 2, or Sars-CoV-2, causes a disease called Covid-19. While the number of cases in the U.S. is low, officials have warned the virus could spread further. But there are precautions you can take, such as washing hands frequently.

• Hospitals and public-health officials in the U.S. and Europe are rationing medical masks and scrounging for more.

Get answers to more questions about the virus in our updated Q&A.

What Else We're Reading

What would a coronavirus outbreak in the U.S. mean for schools? (New York Times)

One of the biggest rights holders of the Olympics, the media company Discovery, said it had insurance to protect itself from a loss of revenue if the Tokyo Olympics are canceled. (Associated Press)

Amazon.com said it banned more than 1 million products that inaccurately claimed to cure or protect against the coronavirus. (Reuters)

The Centers for Disease Control and Prevention has a comprehensive page about the virus and its spread. (CDC)

The World Health Organization's coronavirus disease situation reports are updated daily. (WHO)

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