U.S. stocks plummeted Tuesday after the Federal Reserve’s emergency rate cut failed to bring calm, extending the mayhem that has defined the markets for days over growing concerns the coronavirus will blunt economic growth.

The Dow Jones industrial average sank nearly 3 percent, 786 points, and the yield on the U.S. 10-year Treasury bond — a foundation of global finance — briefly fell below 1 percent, before recovering slightly, as investors fled equities for the safety of bonds. Investors are worried that the spreading outbreak will upend the global economy and end the decade-long expansion.

The Standard & Poor’s 500 and Nasdaq composite closed off about 3 percent. All 11 S&P stock market sectors were in negative territory, with technology and financials faring the worst. Lower interest rates have an adverse effect on the profits of banks and financial services companies. All but one of the 30 Dow components finished the day in the red. American Express, 3M and Microsoft were the Dow’s biggest losers. Only Coca-Cola stayed positive.

Stocks twisted and turned most of the day, despite the central bank announcing it would slash the benchmark U.S. interest rate by half a percentage point.

“The Fed went a little early,” said Jamie Cox, managing partner of Harris Financial Group. “Everybody knew the Fed was going to lower interest rates, but they left markets with a lot more questions than answers. That’s why the early-morning bounce was quickly sold.”

The Fed, whose leaders were unanimous in their decision to bring the rate to just below 1.25 percent, had not taken such an emergency step since 2008. The announcement came after the Group of Seven failed to offer a specific course to combat the economic fallout from the outbreak, which has upended global supply chains since the first cases emerged in Wuhan, China, in December.

At a hastily-called news conference this morning, Fed Chair Jerome H. Powell said the central bank took action to help counter the economic risks that have emerged in recent weeks. He said the Fed is in active discussions with other central banks and that any future changes to monetary policy would come based on the best information available at that time.

“We do recognize the rate cut will not reduce the rate of infection. It won’t fix the broken supply chain. We get that … but we do believe our action will provide a meaningful boost to the economy,” Powell said.

Yet, his comments did little to settle markets.

“In times of crisis, the Federal Reserve should just let the policy decision stand on its own,” Cox said. “It’s too easy for those comments to be misconstrued.”

The Fed has been under increasing pressure to take action to quell the anxiety that has roiled global markets for days and filtered down to consumers, who are clearing store shelves of water, disinfectant and shelf-stable food in anticipation of quarantines and shortages. But interest rates were already at low levels, and economists worry that any further reductions will give the central bank less leeway in the event of a recession.

“The Fed’s rate cut is a psychological palliative, but I have severe doubts it will make a difference to economic growth going forward,” said Daniel P. Wiener, chairman of Adviser Investments. “The rate cut is not going to drive consumers out of their homes and into the malls if they fear contagion.”

Vanguard Group, the mutual fund giant with more than $6 trillion under management, called the Fed cut “premature, given the lack of data suggesting a significant drag on the economy.”

“Today’s announcement could send the wrong signal to market participants, including individual investors who are concerned with recent market volatility,” according to a statement from Roger Aliaga-Diaz, Vanguard’s chief economist for the Americas.

The 10-year Treasury yield’s record low beneath 1 percent also rattled markets.

“Two things are driving the 10-year bond yield lower,” said Luke Tilley, chief economist at Wilmington Trust. “First is the Federal Reserve decision to reduce interest rates. Also is the growing concerns about future economic growth and inflation, which are sharply lower the past week because of the coronavirus.”

Dropping bond yields, which decrease as bond prices increase, “means the U.S. Treasury is the safe haven of choice for investors concerned about economic growth and equities,” Tilley said.

Early Tuesday, before the rate cut, President Trump blasted Powell for not doing enough to boost the economy. Even after the announcement, Trump called for further measures.

“The Federal Reserve is cutting but must further ease and, most importantly, come into line with other countries/competitors,” Trump tweeted. “We are not playing on a level field. Not fair to USA. It is finally time for the Federal Reserve to LEAD. More easing and cutting!”

The whirlwind day came just after Wall Street staged an explosive rally, shaking off its worst week since the financial crisis. The Dow surged nearly 1,300 points, closing up 5.1 percent, its largest percentage gain since March 2009. And the three major indexes all exited correction territory, which marks a 10 percent reversal from recent highs.

Yet, at the close of the markets today, all three indexes were back in correction territory.

Earlier today, European markets climbed, with Britain’s FTSE 100, Germany’s DAX and France’s CAC posting gains of roughly 1 percent. In Asia, Japan’s Nikkei fell 1.2 percent and Hong Kong’s Hang Seng finished essentially flat.

Arturo Bris, professor of finance and lead of the IMD World Competitiveness Center at the IMD business school in Lausanne, Switzerland, said that markets and companies could emerge from the current crisis better prepared for the next one, to "prevent the overreaction and panic we’re in now — and help keep markets and economies stable even during the unthinkable.”

Though the outbreak is serious, it "is not the end of the world,” he said. "In addition to making preparations for a pandemic, they also need to be planning for what comes after a pandemic, when things return to normal.”

The coronavirus has caused a rupture in global supply chains, particularly for goods manufactured and produced in China, where economic activity has largely stalled. And the longer fears swirl around its spread, shaky consumer confidence could push Americans to rein in their spending. The world economy is now expected to have its worst year of growth since 2009, according to numerous forecasts. And Goldman Sachs is predicting no growth in the second quarter, which would be the worst quarter the country has experienced in six years.

“Stocks are likely to continue reacting to ebbs and flows in the news cycle, and it is too early to tell if Monday’s 1,300 point rally in the Dow means a bottom is in place for stocks,” said David Bahnsen, chief investment officer of The Bahnsen Group, based in Newport Beach, Calif., with over $2.25 billion in assets under management. “Economic damage has certainly been done, but how severe and for how long, remains to be seen.”

In the United States, the number of confirmed cases surged past 100 in 15 states, with nine people dead. There are at least 27 confirmed cases of coronavirus in Washington state, with evidence suggesting the virus may have spread undetected there for weeks.

Roughly 70 countries have reported incidences of the virus, and new countries are added to the list each day. In South Korea, the number of confirmed cases exceeded 5,000, the highest outside China. Government officials were placed on 24-hour alert, and health tests expanded in virus-hit areas. China, the epicenter of the outbreak and still the worst-hit country, announced its lowest number of new cases since late January.

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