S&amp;P/ASX 20S&amp;P/ASX 20 S&P/ASX 20 The S&P/ASX 20 index is a stock market index of stocks listed on the Australian Securities Exchange from Standard & Poor's. While the "ASX 20" often simply refers to the 20 largest companies by market capitalisation, the S&P/ASX 20 Index is calculated by using the S&P Dow Jones Indices market capitalization weighted and float-adjusted methodologies. All 20 companies also feature in the S&P/ASX 50. Constituent companies. As of May 2021, the constituent stocks of the ASX 20 in alphabetical order by symbol are: S&P/ASX 20 The S&P/ASX 20 index is a