Allegiant says the credit card is the real prize in its Sun Country deal. With United, Breeze, and American trimming service, the bet could hit turbulence. The Merger Closed, Followed By An Admission Allegiant completed its acquisition of Sun Country on May 13, a $1.5 billion deal including about $400 million of assumed debt that creates the largest leisure-focused airline in the US. The combined entity serves roughly 175 cities, more than 650 routes, and a combined fleet of 195 aircraft.