Realogy Corporation is the world's largest real estate franchiser and provider of real estate and relocation services. It owns several major real estate brand franchises such as Century 21, Coldwell Banker, Sotheby's International Realty, and NRT. Realogy is headquartered in Parsippany, NJ and has over 15,000 employees worldwide. It was formed through the acquisition of Century 21 in 1995 and has grown through further acquisitions. Realogy is owned by an affiliate of Apollo Management, a private equity firm.