U.S. stock-index futures signaled a lower open on Wednesday, as retail sales for December disappointed and weak oil prices hit copper and mining stocks.
Already sharply lower, stock futures fell harder after the Commerce Department reported retail sales slid the most in a year last month, down 0.9 percent.
Falling oil prices continue to weigh on global equity markets. On Tuesday, the commodity fell near six-year lows, extending losses after trading lower for seven straight weeks. Meanwhile, copper prices also hit five-and-a-half-year lows overnight, causing severe selling in miners.