BAE Systems plc (BAE) is a British multinational arms, security, and aerospace company. Its headquarters are in London and Farnborough in the United Kingdom with operations worldwide. The company is the largest defence contractor in Europe and among the world's largest defence companies; it was ranked as the third-largest based on applicable 2017 revenues. Its largest operations are in the United Kingdom and United States, where its BAE Systems Inc. subsidiary is one of the six largest suppliers to the US Department of Defense. Other major markets include Australia, India, and Saudi Arabia, which account for about 20% of BAE's overall sales. It is the biggest manufacturer in Britain. The company was formed on 30 November 1999 by the £7.7 billion purchase and merger of Marconi Electronic Sy