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US stocks fell sharply on Monday as investors appeared to shrug off the Federal Reserve's emergency actions on Sunday amid the coronavirus pandemic.

The S&P 500 plummeted 8.1% at the open, triggering a 15-minute marketwide trading halt. The Dow Jones industrial average slipped 9.7%, or 2,250 points, within the first minute.

Selling pressure persisted once trading resumed, with all major US indexes down by 12% to 13% by the close.

The Fed on Sunday cut its benchmark interest rate to near zero and said it would increase bond holdings by $700 billion, among other measures.

"Even if the Fed is able to put a floor under markets, asset prices are unlikely to begin recovering until coronavirus spread plateaus," Seema Shah, chief strategist at Principal Global Investors, told Business Insider.

Read more on Business Insider.

US stocks fell sharply on Monday amid continued worry about the sweeping economic impact of the coronavirus pandemic.

The S&P 500 dropped 8.1% within a minute of the open, triggering a 15-minute marketwide trading halt. The Dow Jones industrial average slipped 9.7%, or 2,250 points, before the stoppage.

Major US stock indexes extended losses in the final hour of trading as President Donald Trump hosted a coronavirus task force briefing. All major US indexes were down by 12% to 13% by the close.

In overnight trading, futures on the S&P 500 hit a so-called limit-down circuit breaker, which prevents declines of more than roughly 5%.

The market's negative reaction suggests traders aren't convinced the stimulus efforts announced by the Federal Reserve on Sunday will be enough to offset the economic harm of the coronavirus outbreak. Investors have been faced with an increasingly uncertain landscape as virus cases have spiked and much of the nation has gone into lockdown.

Here's where major US indexes were trading as of Monday's market close:

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The Fed's actions taken on Sunday included cutting its benchmark interest rate to near zero. The central bank also said it would increase bond holdings by $700 billion and reduce the reserve requirement ratio to 0%. Other central banks around the world responded with similar actions.

"The Fed has thrown most its weight behind this move, offering almost everything it has to give, which raises the inevitable question: If this doesn't work, what will?" Seema Shah, chief strategist at Principal Global Investors, told Business Insider.

She added that "even if the Fed is able to put a floor under markets, asset prices are unlikely to begin recovering until coronavirus spread plateaus."

Elsewhere in risk assets, oil shed as much as 29% and even dipped below $30 per barrel as the collapse of OPEC and its allies threatens to push supply to record levels and the coronavirus outbreak weighs on demand.

Treasuries surged, sending yields lower, as investors snapped up so-called safe-haven assets. Gold, another haven, slumped as investors sold the precious metal for cash amid the market panic.

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Meanwhile, the Cboe Volatility Index, or VIX — commonly known as the stock market's fear gauge — spiked to levels last seen during the financial crisis. Market volatility will "absolutely" continue, Will Rhind, the founder and CEO of GraniteShares, told Business Insider in an interview.

"We definitely have more room to fall," he added.

Airline and cruise-line stocks led declines on Monday as the travel industry faces increased pressure amid the coronavirus pandemic. Shares of Boeing fell more than 20% as it was placed on watch by Fitch credit ratings.

Royal Caribbean, Carnival, and Norwegian Cruise Line all slumped as well. The cruise sector is on watch and has suspended all voyages in response to the outbreak.

Bank stocks also took a hit, with shares of Bank of America, JPMorgan, Goldman Sachs, and Morgan Stanley all falling more than 10%. On Sunday, big banks announced that they would stop share-buyback programs to stay afloat in the economic uncertainty brought on by the pandemic.

"The only certainty at this point is more volatility and I would expect the market to price in a recession," Chris Zaccarelli, the chief investment officer for the Independent Advisor Alliance, told Business Insider.

He continued: "If that turns out to be the case — or if credible and specific fiscal and public health policies are put in place to contain the economic and public health risks — that is when you will begin to see a bottom in the stock market."

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