The Dow Jones Industrial Average slumped 973.65 points, or 4.44 percent, to close at 20,943.51. The S&P 500 fell 114.09 points, or 4.41 percent, to 2,470.50. The Nasdaq Composite Index shed 339.52 points, or 4.41 percent, to 7,360.58.

The three major averages dropped more than 5 percent at session lows.

All the 11 primary S&P 500 sectors pulled back noticeably, with utilities and real estate both down more than 6 percent at the close, representing the two worst-performing groups.

The United States became the first nation with more than 200,000 COVID-19 infections on Wednesday, according to a new tally from Johns Hopkins University.

As of Wednesday afternoon, a total of 203,608 confirmed cases have been reported in the United States, with 4,476 deaths, showed the tally updated by the university's Center for Systems Science and Engineering.

Health experts with the White House Coronavirus Task Force said Tuesday that even with the Trump administration's national social distancing guidelines in place, Americans still should be prepared for the prospect of the coronavirus causing 100,000 to 240,000 deaths in the country.

U.S. President Donald Trump on Tuesday warned that the nation should prepare for "a very painful, very, very painful two weeks."

On the data front, economic activity in the manufacturing sector contracted in March amid the coronavirus fallout, the Institute for Supply Management (ISM) reported on Wednesday. The ISM manufacturing index slipped to 49.1 percent in March from the February reading of 50.1 percent.

U.S. private sector employment decreased by 27,000 jobs from February to March, according to payroll data company Automatic Data Processing on Wednesday.