The carrier announced Tuesday that it will begin charging certain passengers to check their luggage on flights, a significant shift at the company long prized by consumers for its perks.

Southwest Airlines will begin charging customers a fee to check bags. It's a significant change for the budget carrier, which built years of advertising campaigns around its policy of letting passengers check up to two bags for free.

Southwest Airlines ( LUV 7.40%) is making a number of moves designed to boost profitability, including abandoning its decades-long practice of not charging for checked bags. Investors cheered the news, sending Southwest shares up 16% at the open and up 8% as of 10 a.m. Eastern.