The tech-heavy Nasdaq is just about 10 percent below the record closing high set on February 12th - putting the index on the cusp of what is known on Wall Street as a correction.
The Dow shed 345 points. The S&P 500 lost 51 points. The Nasdaq tumbled 274 points.
Thursday's deep stock market declines were sparked by remarks made by Federal Reserve Chairman Jerome Powell that the Fed isn't ready to tweak its easy-money policies. That unnerved some investors who are growing worried about inflation, says Victoria Fernandez, chief market strategist at Crossmark Global Investments.
"I think what may be happening is that the inflation fears that the market is seeing right now, you have Powell saying they are going to be transitory, inflation rises, and so they (the Fed) are not going to move based on those. And perhaps the market is losing a little bit of confidence in the Fed and that they're going to be able to control rising inflation."
Investors got another whiff of inflation from the oil market. Crude oil prices hit highs not seen in more than a year. U.S. crude jumped to nearly $64 a barrel after OPEC and its allies agreed to keep production cuts in place.
Economic numbers didn't provide much comfort. New claims for unemployment benefits jumped to 745,000 last week, as brutal winter storms in the densely populated South added to job woes. Some 18 million American were on unemployment benefits through mid-February. Markets will get a closer look at the employment picture on Friday with the release of the closely-watched monthly jobs report.