A financial trader monitors data on computer screens inside the Frankfurt Stock Exchange in Frankfurt.

Check out which companies are making headlines before the bell:

Delta Air Lines — The airline reported adjusted quarterly profit of $1.70 per share, beating estimates by five cents a share. However, revenue was below forecasts as the key metric of revenue per available seat mile fell 5.6 percent from a year earlier. Delta also said an August outage cost the airline $100 million.