China National Offshore Oil Corporation (CNOOC) is the third-largest national oil company in China, after CNPC (parent of PetroChina), and China Petrochemical Corporation (parent of Sinopec). It focuses on exploration and development of crude oil and natural gas offshore of China. CNOOC Group is owned by the government, and its subsidiary, CNOOC Ltd is listed in Hong Kong. Another subsidiary, China Oilfield Services, is listed in Hong Kong and New York. In July 2012, CNOOC announced an agreement to acquire Nexen, a Canadian oil and gas company, for approximately US$15.1 billion.