The main indexes are on track to finish the week lower and record their steepest monthly decline since May 2012, as recent earnings news has been lackluster, while fears over emerging markets have sent many investors running for cover.
Investors found no solace from U.S. consumer spending data, which showed Americans spent more in December, but their incomes stagnated.
The S&P 500 opened 17 points, or 1%, lower at 1,777.11, and was set to record its third weekly decline in a row. The Dow Jones Industrial Average began the session with a triple-digit loss, falling 187 points, or 1.2%, to 15,666.886. The blue-chip index is headed for the second straight week of losses.
The Nasdaq Composite opened down 34 points, or 0.9%, at 4,088.18. The tech-heavy index is set to register second straight week of declines.