Investors dumped both stocks after the lawsuit was announced Tuesday morning. US Airways shares were down $2.46, or 13%, for the day, and American was down $2.64, or 45%.
"While shareholders might benefit, creditors might benefit from consolidation, the fact of the matter is consumers will get the shaft," Bill Baer, assistant attorney general for the antitrust division, told reporters in a conference call. "The right option here is a full-stop injunction."
The department argued that the competition — and lower prices — would be lost at more than 1,000 pairs of cities where the airlines compete with connecting flights.