JetBlue (JBLU) and Southwest Airlines (LUV) edged lower on Friday after BofA Global Research downgraded both stocks to ‘Underperform’ from ‘Neutral’. According to TheFly, the BofA analyst said both airlines trade at the high end of historical valuation ranges despite less exposure to "the strongest industry trends.

Airline stocks were mixed on Friday after Bank of America upgraded American Airlines Group Inc. and downgraded Southwest Airlines Co. and JetBlue Airways Corp., predicting that the network carriers will continue to outperform low-cost airlines due to demand for premium travel.

The DOT's moves come weeks after issuing a multi-million dollar fine against JetBlue.

Southwest Airlines stock fell Thursday after the Department of Transportation sued the airline over a pair of "chronically delayed flights."

Snag one-way flights for as low as $49 on these airlines right now during winter deals taking place through Jan. 14.

The Transportation Department also announced $650,000 in civil penalties against Frontier Airlines on Wednesday, citing chronically delayed flights. $325,000 will be paid to the U.S. Treasury while the remainder can be suspended if Frontier does not operate more chronically delayed flights in the next three years.

A lawsuit filed against Southwest alleges the airline operated multiple “chronically delayed” flights affecting thousands of passengers.

The US Department of Transportation (USDOT) is suing Southwest Airlines for “illegally operating multiple chronically delayed flights and disrupting passengers’ travel,” according to a press release.