New York--FedEx Corp. on Wednesday unveiled sweeping brand changes, including the renaming of its holding company from FDX Corp. to FedEx. Additionally, the company's express transportation unit, Federal Express, will become FedEx Express and will have a slightly modified logo. FedEx's Roberts Express, the company's expedited delivery service unit, will be renamed FedEx Custom Critical. And RPS, the company's ground, business-to-business service, will be renamed FedEx GroundÃthis unit will also handle the company's new residential delivery service, FedEx Home Delivery, which is slated to begin March 13. Beyond the branding changes, FedEx is instituting organizational changes, which include providing business customers with a single Web site for tracking air, ground and expedited delivery.