Strategists blamed the weakness on rising Treasury yields and concerns that the Fed might delay another rate cut in December; however, the jump in yields at the start of the session has since reversed. Profit taking after such a strong rally was also likely a factor, they said.

The Dow index fell nearly 400 points as stocks hit session lows in afternoon trading. They have since moved slightly higher, but the blue-chip index is still down 314 points, or 0.7%, at 43,429 on the day.

Meanwhile, the S&P 500 and Nasdaq Composite are having their worst week since September 6, according to Dow Jones Market Data.

The S&P 500 fell 82 points, or 1.4%, to 5,866 points in recent trading, while the Nasdaq Composite fell 460 points, or 2.4%, to 43,556 points. The tech-heavy index is on track for its worst trading session since Halloween.

The Dow is down 1.4% for the week in recent trading, while the S&P 500 and Nasdaq are down 2.1% and 3.1%, respectively, according to Dow Jones Market Data.

Small-cap stocks also struggled; The Russell 2000 lost nearly 4% for the week, reversing some of its 8.6% gain from the previous week.