The Atlas Copco Group is a global industrial group of companies headquartered in Nacka, Sweden. In 2015, global revenues totalled SEK 102 billion, and the company employed more than 43,000 people. The company manufactures products at about 100 production sites in more than 20 countries. As of 2015, the United States is the company's largest single market, followed by China. Atlas Copco companies develop, manufacture, service, and rent industrial tools, air compressors (of which it is the world's leading producer), construction and mining equipment such as rock drills, assembly systems. The Group operates in four areas: Compressor Technique, Mining and Rock Excavation Technique, Construction Technique and Industrial Technique.