The Nasdaq managed to eke out an 0.01% gain after plunging as much as 3.5% during the session. After falling as much as 4.2% - more than 1,000 points - the Dow ended the day down 1.4%.
But, after the bell, S&P 500 e-mini futures were up about 1% and the Invesco QQQ Trust ETF was up 1.3% in extended trade.
On Thursday, all three indexes had confirmed corrections by finishing more than 10% below their closing record highs.
Equities found some support after US Federal Reserve Chair Jerome Powell said the fundamentals of the American economy remained strong and that the central bank would act as appropriate to provide support.
But investors had spent most of the day dumping equities for the safety of US Treasuries, pushing 10-year yields to their fourth record low this week.
The virus spread further on Friday, with cases reported for the first time in at least six countries across four continents, battering markets and leading the World Health Organization (WHO) to raise its impact risk alert to "very high."
Some investors voiced concerns about heading into a weekend where they could not trade on new reports about the virus.
"To get an all-clear sign, the market needs evidence it's under control, no flaring up in new countries and that we don't get a significant outbreak in the United States," said Jack Janasiewicz, chief portfolio strategist for Natixis Investment Managers.
Janasiewicz saw the spread of the virus China as a prompt to reduce exposure to riskier assets, and said the next milestone for further risk cuts would be a US outbreak.
The Dow Jones Industrial Average fell 357.28 points, or 1.39%, to 25,409.36; the S&P 500 lost 24.54 points, or 0.82%, to 2,954.22; and the Nasdaq Composite added 0.89 point, or 0.01%, to 8,567.37.
The CBOE volatility index, also known as Wall Street's fear gauge ended the day near its session low, up 0.95 point at 40.11, after rising as high as 49.48.
Of the S&P's 11 major sectors, the rate-sensitive financial index weighed the most on the benchmark S&P 500 index, ending the day down 2.6%. The utilities sector was the S&P's biggest percentage loser with a 3.3% drop. Real estate and consumer staples - also rate-sensitive sectors that are often seen as safe havens - both fell more than 2%.
Yet the energy, technology and communications services index all showed gains for the day.
Declining issues outnumbered advancing ones on the NYSE by a 3.39-to-1 ratio; on Nasdaq, a 1.95-to-1 ratio favored decliners.
The S&P 500 posted no new 52-week highs and 129 new lows; the Nasdaq Composite recorded 19 new highs and 538 new lows.
Trading was brisk on US exchanges with 19.31 billion shares changing hands compared with a 9.25 billion-share average for the last 20 days.