The Dow Jones Industrial Average fell another 1,338.46 points Wednesday, dropping below the 20,000 mark for the first time since 2017 and effectively erasing all the gains made since President Donald Trump took office,  according to multiple news reports.

The New York Stock Exchange was forced to temporarily suspend trading for the fourth time in two weeks after the S&P 500 fell about 7% in afternoon trading.

The index later pared some of the losses to close down 5.2%.

The early sell-off triggered by uncertainty over the coronavirus pandemic erased nearly all of the gains from the previous day respite.

The Dow closed at 19,898.92, or 6.3% —a dramatic drop from the record high of 29,551 in February. The market has now lost about one-third of its value, according to ABC News.

It was the eighth straight day the Dow has moved by more than 1,000 points, The Associated Press reports.

The Nasdaq Composite closed down 4.7 % to 6,989.84.

In another sign of the expanding crisis, the NYSE plans to temporarily close the trading floor beginning Monday and conduct all business electronically, according to Bloomberg News and other reports.

Oil prices had another jaw-dropping skid Wednesday, sending the price of U.S. crude oil below $22 a barrel for the first time since 2002.

Benchmark U.S. oil lost $6.58, or 24.4%, to settle at $20.37 a barrel. Brent, the international standard, dropped $2.85, or 13.4%, to close at $24.88.

Boeing shares fell more than 17% to lead the Dow lower, CNBC reported. United Technologies and American Express also dropped more than 12%. Energy was the worst-performing sector in the S&P 500, tumbling nearly 10% as U.S. crude prices fell to their lowest levels in 18 years. West Texas Intermediate futures dropped 15.5% to $22.73 per barrel.

Economic stimulus

The U.S. Treasury Department, meanwhile, is proposing sending $500 billion to millions of Americans in two waves of direct payments, with the first round of checks coming April 6, according to The Associated Press.

The stimulus payments are part of a proposed $1 trillion package being proposed by the Trump administration in response to the widening economic fallout from coronavirus.

The sell-off on Wall Street swept markets around the world.

Even prices for longer-term U.S. Treasurys, which are seen as some of the safest possible investments, fell as investors flocked to the very shortest-term Treasury debt.

Despite all that, investors are struggling with how much to pay for anything — stocks, bonds, oil — when it’s so uncertain how badly the economy is getting hit, how much profit companies will make and how many companies may go into bankruptcy due to a cash crunch.

“These are truly unprecedented events with no adequate historical example with which to precisely anchor our forecast,” Deutsche Bank economists wrote in a report Wednesday.

With all the uncertainty and early evidence that China’s economy was hit much harder by the virus than earlier thought, they now see “a severe global recession occurring in the first half of 2020.”

But they also are still forecasting a relatively quick rebound, with activity beginning to bounce back in the second half of this year in part because of all the aid promised from central banks and governments.

Earlier trading

Global stock markets were sinking Wednesday before the opening bell of the U.S. stock market in a third day of roller-coaster price swings after President Donald Trump and other world leaders proposed trillions in aid to get their economies through the coronavirus outbreak.

European stock indexes lost 5% following broad losses across Asia, while trading in Wall Street futures was suspended once again as losses hit the maximum 5% limit.

Bloomberg News reported earlier in the day that the British pound had fallen to the lowest level since 1985 against the U.S. dollar.

Bank of England governor Andrew Bailey called the pandemic an “incredibly fast-moving, financial emergency,” and warned “there will be a big downturn.”

When markets opened Wednesday, major Asian stock markets were initially higher. Benchmarks in Shanghai, Tokyo and Hong Kong all advanced for a moment but didn’t hold.

What’s the plan

The White House proposal could approach $1 trillion in spending to ward off the pressure of business closures to contain the virus. The Federal Reserve has announced more measures to keep financial markets operating.

Treasury Secretary Steven Mnuchin said Trump wants to send $1,000 checks to Americans in the next two weeks to help support them while more parts of the economy come closer to shutting down.

The moves add to efforts from governments around the world that include trillions of dollars of loans for businesses, tax deferrals, mortgage relief and grants. Trump's proposal would include $250 billion for small businesses and $50 billion for airlines.

That is a good start, but investors need to see the number of infections slow before markets can find a bottom, analysts said. The number of new cases reported in China, where the virus emerged in December, is declining, but infections in the United States, Europe and elsewhere are increasing.

There are “green shoots of risk appetite emerging, and some further concerning aspects,” said Chris Weston of Pepperstone Group in a report. “I am not going to call a bottom in the risk story by any means.”

Previously

The Dow has now lost three years of gains in three weeks, according to CBS News.

On Monday, the Dow lost nearly 3,000 points after Trump said a recession may be on the way. The S&P is down 29.2% from its record set last month, though it’s still up 12.1% since Election Day 2016.

On Tuesday, the S&P rose by an unusually wide daily margin of 6%, regaining just under half the previous day’s history-making loss. The Dow advanced 5.2%.

— Reporting by Joe McDonald of The Associated Press was used to supplement this report.