Airline stocks were falling ahead of the open Wednesday as a number of major carriers warned of higher fuel costs.
Southwest Airlines was the sharpest faller, tumbling 4.3%, after cutting its outlook for the third quarter. The low-cost carrier sees revenue per available seat mile falling between 5% and 7% year-over-year, from a previous range of 3% to 7% lower. United Airlines also issued a warning over fuel costs, noting that jet fuel prices have risen more than 20% since the middle of July. It hiked fuel price estimates to between $2.95 and $3.05 per gallon–from a previous range of $2.50 to $2.80.