Hochtief is a German construction company based in Essen, North Rhine-Westphalia, Germany. Hochtief is Germany's largest construction company and operates globally, ranking as one of the largest general construction companies in the United States through its Turner subsidiary, and in Australia through a 55 % shareholding in the Leighton Construction company. In 2010, it employed more than 70,000 employees across five corporate divisions. One of these, Hochtief Concessions, is a major airport operator. The others are involved with construction project planning, finance, construction and operation. In late 2010, Spanish construction company Grupo ACS, which already owned a 30 percent stake in Hochtief, launched a bid that would allow ACS to acquire an additional 20 percent stake in Hochtief. The bid was approved by the German Federal Financial Supervisory Authority (BaFin) on 29 November 2010. ACS raised its stake in Hochtief to 50.16 percent in June 2011, effectively taking over control of Hochtief.