Stocks fell sharply Monday — with the Dow suffering its worst day since the "Black Monday" market crash in 1987 and its third-worst day ever — even after the Federal Reserve embarked on a massive monetary stimulus campaign to curb slower economic growth amid the coronavirus outbreak.

The Dow Jones Industrial Average closed 2,997.10 points lower, or 12.9%, at 20,188.52. The 30-stock Dow was briefly down more than 3,000 points in the final minutes of trading. The S&P 500 dropped 12% to 2,386.13 — hitting its lowest level since December 2018 — while the Nasdaq Composite closed 12.3% lower at 6,904.59 in its worst day ever.

"The markets are getting no break with yesterday's historic Fed actions and COVID-19 dominating the world's headlines," Frank Cappelleri, executive director at Instinet, said in a note. "While the news continues to worsen and with the price action doing things we've only seen a handful of other times in the last century, it's nearly impossible to keep things in perspective."

"We can't argue the facts, and we're dealing with a much bigger issue than just the economy," Cappelleri said.

The major averages fell to their lows into the close after President Donald Trump said the worst of the outbreak could last until August. He also told reporters the U.S. "may be" heading into a recession.

"The market didn't hear what it wanted to hear. I don't think that it wanted to hear that this was going to last until July and August, and now the market does the math. If it lasts until July and August, that means we maybe have a contraction in the second quarter and the third quarter, and that means recession," BNY Mellon strategist Liz Young said on CNBC's "Closing Bell."

Monday's losses put the Dow down 31.7% from its all-time high and the S&P 500 and Nasdaq more than 29% below their records last month. The Dow fell to its lowest point since 2017.

The Dow's drop was the worst decline since its "Black Monday" crash three decades ago when it fell more than 22%. The drop surpassed its 9.99% tumble last Thursday. It was also the Dow's third-worst day ever; it dropped more than 13% in late 1929.