The Dow and S&P 500 had on Monday their biggest one-day losses since 1987, falling 12.9% and 12%, respectively.
Even traditional safe havens cratered as fearful investors decided cash is king.
Data showed USA retail sales fell in February, indicating the main driver of the economy, consumer spending, had begun to slow even before outbreak containment measures began. Share prices are volatile after a brutal sell-off that gave the US stock market its worst loss in more than three decades.
On Sunday evening, the Fed took the extraordinary move of cutting rates by one percentage point to near zero. "And I want to congratulate the Federal Reserve", he said. "Investors are looking around hoping, praying, that there will be a big fiscal package yet to come from Washington - but getting nervous that it might not". "If we do a really good job, we'll not only hold the death down to a level that is much lower than the other way, had we not done a good job, but people are talking about July, August, something like that", Trump told reporters during a White House briefing Monday afternoon.
Mnuchin also said the stock market will remain open despite the recent volatility, although he said its hours could be shortened if needed.
It heightened alarm about the rapid spread of the pandemic and how it has paralyzed parts of the global economy and squeezed company revenue.
Rate-sensitive financial stocks plunged 9.6pc, leading declines among the major S&P sectors. However, the complete opposite has been seen with bullion down five straight days and prices fell another 4% on Monday, despite the wave of risk aversion sweeping through markets. European stocks swung from gains to losses.
The S&P 500 posted no new 52-week highs and 341 new lows; the Nasdaq Composite recorded three new highs and 1,477 new lows.
The S&P 500 and Nasdaq closed the day with a decline of around 12 percent each.
Nearly nothing was left unscathed. Oil, already slammed by a Saudi-instigated price war, slid to less than $30 a barrel to lows last seen in early 2016.
They say the Fed's move made investors believe the situation is more serious than they had imagined. The S&P/TSX Composite Index, meanwhile, lost more than 1,355 points or nine per cent. South Korea's KOSPI was down 3.2%. Australian shares tumbled nearly 4% and futures retreated in Japan.
USA and Chinese data underscored just how much economic damage the disease can cause, with official numbers in China showing the worst drops in activity on record.
Manufacturing data released from China over the weekend were a troubling indication of what could happen in the USA, with retail sales down by 20.5 percent and industrial output down by 13.5 percent.
Manufacturing activity in NY state also plunged in March by the most on record to its lowest level since 2009, offering an early glimpse of the coronavirus' damaging impact on the USA economy.
The dollar index rose 0.176%, with the euro up 0.63% to $1.1175.
In currency trading, the dollar rose to 107.08 Japanese yen from 105.90 yen.