Showa Denko is one of Japan's leading producers of chemicals and industrial materials. The company's sectors include petrochemicals (olefins, organic chemicals, plastic products), aluminum (aluminum cans, sheets, ingots, foils), electronics (semiconductors, ceramic materials, hard disks), chemicals (industrial gases, ammonia, agrochemicals), and inorganic materials (ceramics, graphite electrodes). The petrochemicals segment is its largest division, accounting for more than a third of sales. Showa Denko has more than 180 subsidiaries and affiliates. It was formed in 1939 when Nihon Electrical Industries and Showa Fertilizers combined.