The Dow Jones Industrial Average plummeted more than 1,000 points at close on Monday, marking its worst single-day drop in more than two years, as the number of coronavirus infections around the world have surged.
The S&P 500 and Nasdaq also tumbled Monday, by more than 3.3% and 3.7%, respectively.
United Health, American Express, Cisco, Visa, Walgreens and Apple were among the worst performers Monday, all falling more than 4%.
As markets opened Monday, the Dow was down more than 900 points after reports that the worldwide death toll from the novel coronavirus had risen to 2,612. A vast majority of those deaths -- more than 2,500 -- were in China.
Outside of China, there have also been reports of the virus spreading rapidly in Japan, South Korea and Italy.
"The coronavirus might be slowing in mainland China, but the huge jump over the weekend to various other countries has many reassessing 2020 growth estimates," Ryan Detrick, the senior market strategist for LPL Financial, said in a commentary about Monday's market sell-off.
"The IMF already lowered China’s growth this year, but should the virus continue to spread to other parts of the world, we could see quickly decreasing earnings and growth outlooks," Detrick added.
Experts say the volatile market reactions show how much uncertainty still surrounds the outbreak of the novel coronavirus, officially named COVID-19.
"Markets were hit with renewed fears over coronavirus and the potential economic impact resulting from the shift of the viral outbreak being more of pandemic problem," Charlie Ripley, the senior investment strategist for Allianz Investment Management, said in a statement.
"The interruption to business and supply chains is becoming more prevalent as companies like Apple have already warned investors of the setback the virus has caused," Ripley added. "Additionally, we expect the transportation industry to be affected as travelers cancel flights, hotels and other travel arrangements. During past events of this nature we tend to see a relatively quick recovery, but markets continue to grapple with the uncertainty surrounding the coronavirus and the timing around the peak of its widespread harm to both human life and the economy."
Meanwhile, demand for haven assets such as U.S. treasuries and gold spiked.
Apple told investors last week that its worldwide iPhone supply will be "temporarily constrained" due to outbreak and that it does not expect to meet the revenue guidance it provided for the second quarter.
A handful of other U.S. and international companies have already begun to feel the financial impacts of the outbreak that has crippled the world's second-largest economy.