The Australian Securities Exchange (ASX) is the primary stock exchange in Australia. The ASX began as separate state-based exchanges established as early as 1861. Today trading is all-electronic and the exchange is a public company, listed on the exchange itself.

The Australian Securities Exchange as it is now known resulted from the merger of the Australian Stock Exchange and the Sydney Futures Exchange in December 2006.

The biggest stocks traded on the ASX, in terms of their market capitalization, include BHP Billiton, Commonwealth Bank of Australia, Telstra Corporation, Rio Tinto, National Australia Bank and Australia and New Zealand Banking Group. As at 31-Dec-2006 the three largest sectors by market cap were financial services (34%), commodities (20%) and listed property trusts (10%).

The major market index is the S&P/ASX 200, an index made up of the top 200 shares in the ASX. This supplanted the previously significant All Ordinaries index, which still runs parallel to the S&P ASX 200. Both are commonly quoted together. Other indices for the bigger stocks are the S&P/ASX 100 and S&P/ASX 50.

The ASX is a public company, and its own shares are traded on the ASX. However, the corporation's charter restricts maximum individual holdings to a small fraction of the company.

While the ASX regulates other listed companies listed on the ASX, it cannot regulate itself, and is regulated by the Australian Securities and Investments Commission (ASIC).

The current managing director Robert Elstone was appointed in July 2006. Prior to the merger of ASX with the Sydney Futures Exchange (SFE), Robert Elstone was the CEO of the SFE.