U.S. stocks plunged Monday—suffering their worst day since the "Black Monday" market crash in 1987—even after the Federal Reserve (Fed) began a massive monetary stimulus campaign to limit slowing economic growth amid the coronavirus pandemic. Trading was halted for 15 minutes shortly after the opening as an 8.1 percent drop in the Standard & Poor's 500 triggered a "circuit breaker." It was the third time in the last week that trading was halted due to sharp losses. The major averages fell to their lows after President Donald Trump, who for weeks has downplayed the severity of the pandemic, acknowledged the worst of the outbreak could last until August and said the U.S. economy "may be" heading into a recession. Monday's losses put the Dow industrials down 31.7 percent from their record high and the broader S&P 500 and the technology-heavy Nasdaq more than 29 percent below their records set last month. The Dow Jones industrial average fell 2,997.10, or 12.9 percent, to 20,188.52, its lowest level since 2017. The S&P 500 index fell 324.89, or 12 percent, to 2,386.13, its lowest level since December 2018. The Nasdaq composite index fell 970.28, or 12.3 percent, to 6,904.59, recording its worst day ever.