British Airways (BA) is the flag carrier and the second largest airline in the United Kingdom based on fleet size and passengers carried, behind easyJet. The airline is based in Waterside near its main hub at London Heathrow Airport. In January 2011 BA merged with Iberia, creating the International Airlines Group (IAG), a holding company registered in Madrid, Spain. IAG is the world's third-largest airline group in terms of annual revenue and the second-largest in Europe. It is listed on the London Stock Exchange and in the FTSE 100 Index.