New York - Airline fares within the U.S. are inching higher again.

American Airlines confirmed Thursday that it raised domestic fares $5 each way. J.P. Morgan said Southwest Airlines followed by raising prices on tickets bought within a week of the flight and favored by business travelers.

Southwest did not immediately comment.

Airlines had raised prices just five weeks ago, and J.P. Morgan analyst Jamie Baker said he wasn’t expecting another round of increases so soon. Spot prices for jet fuel, a major airline expense, have dipped since May.

In midday trading, shares of American Airlines Group Inc. were up $1.59, or 5.1%, to $32.69; Southwest rose $1.40, or 2.8%, to $52.21, United Continental Holdings Inc. gained $2.67, or 3.2%, to $86.46; and Delta Air Lines Inc. climbed $1.24, or 2.2%, to $56.69.