Delta Air Lines Inc. (NYSE: DAL) was sued for more than $1 billion by one of its own pilots, who claims he developed a text-messaging app for flight crews that the airline stole and used as the basis for its own app. Captain Craig Alexander sued Atlanta-based Delta for trade-secrets theft in Georgia state court on Monday. DAL’s shares are 24% down from their highs as Delta variant reverses the trend for re-opening trades. Stocks are flat for 2021.