Frontier Airlines and Spirit Airlines, the two largest discount carriers in the U.S., have agreed to merge in a deal valued at $6.6 billion, creating what would become the fifth-largest airline in the country.

The merger gives Denver-based Frontier Airlines a 51.5% controlling stake in the combined airline. Spirit investors will receive 1.9126 shares of Frontier plus $2.13 in cash for each share they own, giving Spirit shareholders an implied value of $25.83 per share, which is a 19% premium over the value of Spirit shares at the end of last week, the companies said.

Spirit Airlines president and CEO Ted Christie said: “We are thrilled to join forces with Frontier to further democratise air travel.

“This transaction is centered around creating an aggressive ultra-low fare competitor to serve our Guests even better, expand career opportunities for our Team Members and increase competitive pressure, resulting in more consumer-friendly fares for the flying public. We look forward to uniting our talented teams to shake up the airline industry while also continuing our commitment to excellent guest service.” Read more.