The Dow was down about 320 points, or 0.7%, at around 43,872, on pace for its biggest percentage decline since Aug. 1, when it tumbled 1.2%, according to FactSet.
The S&P 500 was 23 points, or 0.4%, lower, near 6,321.
The Nasdaq was down 23 points, or 0.1%, at about 21,150.