Wall Street plunges, S&P 500 erases 2018's gains
The final numbers of the day are shown above the floor of the New York Stock Exchange in New York, U.S., February 5, 2018. REUTERS/Brendan McDermid · Reuters

By Lewis Krauskopf

(Reuters) - U.S. stocks plunged in highly volatile trading on Monday, with both the S&P 500 and Dow Industrials indices slumping more than 4.0 percent, as the Dow notched its biggest intraday decline in history with a nearly 1,600-point drop and Wall Street erased its gains for the year.

The declines for the benchmark S&P 500 index and the Dow Jones Industrial Average were the biggest single-day percentage drops since August 2011, a period of stock-market volatility marked by the downgrade of the United States' credit rating and the euro zone debt crisis.

The question now for investors, who have ridden a nearly nine-year bull run, is whether this is the long-awaited pullback that paves the way for stocks to again keep rising after finding some value, or the start of a decline that leads to a bear market.

"A lot of people who have been in this market for the past three or four years have never seen this before,” said Dennis Dick, a proprietary trader at Bright Trading LLC in Las Vegas. “The psychology of the market changed today. It’ll take a while to get that psychology back.”

After regular trading hours on Monday, S&P 500 E-mini stock futures rose 0.73 percent, suggesting some traders expect Wall Street to open with a gain on Tuesday.

Bulls argue that strong U.S. corporate earnings, including a boost from the Trump administration's tax cuts, will ultimately support market valuations. Bears, including short sellers that bet on the market decline, say that the market is over-stretched in the context of rising bond yields as central banks withdraw their easy money policies of recent years.

The U.S. stock market has climbed to record peaks since President Donald Trump's election, on the prospect of tax cuts, corporate deregulation and infrastructure spending, and it remains up 23.8 percent since his victory. Trump has frequently taken credit for the rise of the stock market during his presidency, though the rally and economic recovery was well underway during the Obama administration.

As the stock market fell on Monday, the White House said the fundamentals of the U.S. economy are strong. U.S. economic growth was running at a 2.6 annualized rate in the fourth quarter last year and the unemployment rate is at a 17-year low of 4.1 percent.

On Monday, the financial, healthcare and industrial sectors fell the most, but declines were spread broadly as all major 11 S&P sectors dropped at least 1.7 percent. All 30 of the blue-chip Dow industrial components finished negative.

With Monday's declines, the S&P 500 erased its gains for 2018 and is now down 0.9 percent in 2018. The Dow is down 1.5 percent for the year.