Hari Adhikari, associate professor of finance at Embry-Riddle Aeronautical University, said Spirit's strong presence in Florida and South America might have made it an attractive acquisition for JetBlue. He also noted that a potential Frontier-Spirit merger, which could put JetBlue at a competitive disadvantage, might also have led to the offer. He said it's possible all three carriers could merge at some point if regulators approve.