According to wikipedia:EligibilityTo be eligible for inclusion...

According to wikipedia:

Eligibility

To be eligible for inclusion in the ASX 200 Index:

• Market capitalization: A stock's weight in the index is determined by the float-adjusted market capitalization of the stock. This is a function of current index shares, the latest available stock price and the Investable weight factor (IWF). The IWF represents the float-adjusted portion of a stock's equity capital. Therefore, any strategic holdings that are classified as either corporate, private or government holdings reduce the IWF which, in turn, results in a reduction in the float-adjusted market capital. Shares owned by founders, directors of the company, trusts, venture capitalists and other companies are also excluded. These are also deemed strategic holders, and are considered long-term holders of a stock's equity. Any strategic shareholdings that are greater than 5% of total issued shares are excluded from the relevant float.
• Liquidity: The trading volume in terms of dollar value and the number of transactions must exceed at least 0.025% of the sum of all eligible securities' trading volume. To ensure that no single company dominates trading, they are capped at a maximum of 15% for value, volume and transactions.
• Listing: Only stocks listed on the Australian Stock Exchange will be considered for inclusion in any of the S&P/ASX indices.

https://en.wikipedia.org/wiki/S%26P/ASX_200