BHP Billiton was formed in 2001 through the merger of the Australian Broken Hill Proprietary Company Limited (BHP) and the Anglo–Dutch Billiton plc, forming a dual-listed company. The Australia-registered Limited has a primary listing on the Australian Securities Exchange - The ASX - and is one of the largest companies in Australia by market capitalisation. The English-registered plc arm has a primary listing on the London Stock Exchange and is a constituent of the FTSE 100 Index.