The Department of Transportation (DOT) launched an investigation into rewards programs at the four largest airlines over "potential unfair, deceptive, or anticompetitive practices."  U.S. Secretary of Transportation Pete Buttigieg sent letters to American, Delta, Southwest and United Airlines requiring them to hand over records with detailed information about their rewards programs, practices and policies. The department is aiming to combat any deceptive or anticompetitive practices that may occur, such as ...