Occidental Chemical Corporation, headquartered in Dallas, Texas, is a leading manufacturer of polyvinyl chloride (PVC) resins, chlorine and caustic soda. Within OxyChem is OxyVinyls, which also manufactures vinyl chloride monomer (VCM), and its precursor, ethylene dichloride (EDC). It is the largest VCM producer and the third-largest PVC supplier in the United States. Globally, Oxy is the second-largest merchant marketer in the world of chlorine and the largest marketer of its co-product caustic soda—both of which are necessary for the creation of PVC.