BAE Systems plc is a British multinational defence, security and aerospace company headquartered in London in the United Kingdom and with operations worldwide. It is among the world's largest defence contractors; it ranked as the second-largest based on applicable 2012 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. The company was formed on 30 November 1999 by the £7.7 billion merger of two British companies; Marconi Electronic Systems (MES) – the defence electronics and naval shipbuilding subsidiary of the General Electric Company plc (GEC) – and British Aerospace (BAe) – an aircraft, munitions and naval systems manufacturer.