American will match competitors’ prices on any nonstop route, its president, Scott Kirby, said on an investor call. The airline’s move to sell cheap fares with more restrictions highlights how competition is intensifying between the largest U.S. airlines and low-cost rivals, such as Spirit Airlines Inc (SAVE.O) and Southwest Airlines Co (LUV.N). Sterne Agee CRT analyst Adam Hackel said American’s vow to compete may have made investors jittery.