Discount airline’s shares rise as Jefferies analyst upgrades the stock, citing an earnings boost from luggage fees.

After today, customers can expect baggage fees when flying with Southwest Airlines as the airline moves to officially eliminate its "bags fly free" policy on May 28. The Dallas airline has finally revealed that the first checked bag will set customers back $35 while the charge to check a second bag will be $45—with some exceptions.

Until now, it was the only major U.S. airline that allowed passengers to check two bags at no extra cost. On May 28, most passengers will start paying $35 for their first bag.