ThyssenKrupp AG is a German industrial engineering and steel production multinational conglomerate. It resulted from the 1999 merger of Thyssen AG and Krupp and has its operational headquarters in Duisburg and Essen. The company says that it is one of the largest steel producers in the world, and it was ranked tenth-largest worldwide by revenue in 2015. It is divided into 670 subsidiaries worldwide. The largest shareholders are the Alfried Krupp von Bohlen und Halbach Foundation and Cevian Capital. ThyssenKrupp's products range from machines and industrial services to high-speed trains, elevators, and shipbuilding. The subsidiary ThyssenKrupp Marine Systems also manufactures frigates, corvettes, and submarines for the German and other navies.