An exchange formed in 1987 by the Australian Parliament by consolidating six independent stock exchanges that had operated in the capital cities of the Australian states. Those individual exchanges had been in existence since the 19th century. In 1994, the first stage of an electronic clearing and settlement system (CHESS) was introduced and was fully implemented in 1996. During that same year, the ASX voted to demutualize, and phase two of CHESS was implemented, which allowed the shares of foreign companies to be settled. During the latter half of the 1990s, the number of finance, insurance, communications, and media companies increased dramatically, thereby diversifying the stock market from its heavy concentration of mining and natural resources companies. Equities, fixed-income securities, and derivatives trade on the ASX. Its lead index is the All Ordinaries Index, which is comprised of the largest 500 companies.