Rival United Parcel Service UPS.N shed 6.8%, XPO Logistics XPO.N dropped 11.2% and e-commerce giant Amazon.com AMZN.O slipped 2.8%, while U.S. stock futures EScv1 were knocked down overnight after FedEx's results. Sept 16 (Reuters) - Shares of FedEx FDX.N slumped in premarket trading on Friday as the global delivery heavyweight's forecast withdrawal sounded alarm about softening consumer demand and hammered equities in the sector worldwide. FedEx's weak result highlights the difficult macroeconomic backdrop as elevated inflation and concerns about slowing global growth dent shipping volumes, said Victoria Scholar, head of investment at Interactive Investor.