According to Reuters, the US Department of Transportation (DOT) announced on September 6th that it will investigate the rewards and frequent flyer programs of the four major US airlines to ensure that consumers do not face unfair, fraudulent, or anti-competitive practices. US Transportation Secretary Pete Buttigieg sent a letter to American Airlines, Delta Air Lines, Southwest Airlines, and United Airlines, requesting them to provide records and submit reports to answer detailed questions about their rewards programs. The department is examining how consumers are affected by "reward devaluation, implicit or dynamic pricing, additional fees, and reduced competition and choice."