The spread of the virus could cost China, the world's second biggest economy, tens of billions of dollars in lost growth this quarter alone. Major outbreaks in Japan, South Korea and Italy underscore the risk posed to other big economies from the coronavirus.
Investors are concerned about how the coronavirus is weighing on consumer demand, manufacturing supply chains and major economies around the world.
Here's what markets are doing today:
European markets were sharply lower in early trading on Wednesday as corporate profit warnings added to fears about the economic impact of the outbreak.
Germany's DAX dropped as much as 3% before recovering some losses, while the CAC 40 shed 1.2% in Paris and the FTSE 100 dipped 1.1% in London.
Losses were less dramatic in Asia, where Japan's Nikkei 225 dropped 0.8%. Hong Kong's Hang Seng Index gave up 0.7% and the Shanghai Composite lost 0.8%.
The declines follow a terrible day in the United States, where the Dow finished 879 points, or about 3.2% lower. The index has now lost more than 2,000 points in total over the past four trading days.