International Consolidated Airlines Group S.A., trading as International Airlines Group and usually shortened to IAG, is a British-Spanish multinational airline holding company with its registered office in Madrid, Spain, and its corporate headquarters in London, England. It was formed in January 2011 after a merger agreement between British Airways and Iberia, the flag carriers of the United Kingdom and Spain respectively, when British Airways and Iberia became wholly owned subsidiaries of IAG. British Airways shareholders were given 55% of the shares in the new company. Since its creation, IAG has expanded its portfolio of operations and brands by purchasing other airlines – BMI, Vueling and Aer Lingus. The group also owns Level and Avios, a frequent-flyer program. The company is listed on the London Stock Exchange and the Madrid Stock Exchange. It is a constituent of the FTSE 100 Index and IBEX 35 Index. Wikipedia