AREX, spelled A'REX as a brand name, is a South Korean commuter rail line that links Seoul with Gimpo Airport and Incheon International Airport. The section between the two airports opened on March 23, 2007, the extension to Seoul Station opened December 29, 2010. The line was built and operated by a private company, but after financial difficulties, South Korean national rail operator Korail bought a majority stake (88.8%) and the operating company was renamed Korail Airport Railroad Co., Ltd..