The S&P finished down 2.1 percent while the Dow closed down 2.06 percent. Both indexes had their worst day since Feb. 3, 2014. On that day the S&P was down 2.28 percent and the Dow finished down at 2.06 percent.
The slide came a day after the Federal Reserve released the minutes from its July meeting. Most analysts interpreted the minutes as less indicative of a September rate hike. Wall Street had previously anticipated that the Fed might have more reason to move next month.
Here are some other milestones hit in this trading session:
—CNBC's Gina Francolla and Christopher Hayes contributed to this report.