South Korea's antitrust watchdog is investigating luxury brands for their contracts terms with leading department stores amid criticism that they are enjoying significantly lower sales commissions and other business favors than smaller vendors from domestic retail giants, officials said Tuesday. The Fair Trade Commission (FTC) recently sent investigators to the offices of eight luxury brands -- Chanel, Gucci, Louis Vuitton, Cartier, AmorePacific, Cheil Industries, LG Fashion and MCM -- to secure documents and materials related to the investigation, according to the officials.