Frontier's first takeover bid in 2022, for $2.9 billion in cash and stock, was foiled by a $3.8 billion offer from rival JetBlue ( JBLU ). Spirit filed for bankruptcy in November after a federal judge sided with the Justice Department to block its tie-up with JetBlue. The low-cost carrier model works by offering cheaper seats than traditional airlines to domestic and near-US destinations while charging fees for items like checked bags, seating selection, and snacks or drinks. Often, the airlines will use secondary airports with lower landing fees, such as Long Beach Airport in Los Angeles instead of LAX. But between increased competition from traditional carriers in domestic routes and rising labor and maintenance costs, the low-cost model has slowly unraveled. For example, amid activist investor pressure last year, Southwest ( LUV ) announced it would end its decades-long practice of open seating as part of a new strategy to grow revenue.