The S&P/ASX 200 Index is the benchmark institutional investable stock market index in Australia, comprising the 200 largest stocks by float-adjusted market capitalization. It is one of a number of indices published by S&P Dow Jones on Australian markets (called the S&P/ASX family of indices), but is considered the main benchmark of that grouping.
The S&P/ASX 200 is designed to measure the performance of the 200 largest index-eligible stocks listed on the Australian Securities Exchange (ASX) by float-adjusted market capitalization. Index constituents are drawn from eligible companies listed on the ASX. Companies have to be listed on the ASX to be included, but these can be either primary or secondary listings (a secondary listing is that by a company which has its primary listing in another country or on another exchange). All common and preferred stocks are eligible for inclusion, but hybrid stocks (securities that have some fixed income characteristics) are not.