What are the ASX index company weightings?

In today's Big Question, subscriber Stuart Dalgleish of Metung, Victoria, asks: Where can I find individual company weightings for constituents of the S&P/ASX 200 or 300? I have located lists of companies that make up each index, but not the individual weightings.
The response comes from Elio D'Amato, a director of Lincoln Indicators:

The individual weighting of stocks is a process administered by the Standard & Poor’s Australian Index Committee. The committee has five members, representing Standard & Poor’s (S&P) and the Australian Stock Exchange (ASX). It is the responsibility of the committee to determine index composition.

Classifying the individual weighting of a company within the index is adjusted regularly according to a combination of factors such as a company’s size, market liquidity and its investable weight factor (IWF).

A stock’s IWF is based on its “free float”, which, simply put, is the percentage of its shares that are freely available for trading in the local market. A discount will be applied if there are significant holdings by minimal shareholders, parent entities or organisations such as governments. The index committee reviews IWFs annually, buy any single event that alters the free float of a company by more than 5% will be reviewed as soon as practicable.

Standard & Poor’s owns the rights to the information, which institutions can subscribe to for a fee. As a result, individual company weightings are unfortunately not available in a public forum to retail investors. However, many retail investors can access this information from publications such as the Eureka Report, their broker, brokering software such as IRESS or some other “paid for” service provider.

Unfortunately if you are unable to access this information, then the best that is available to investors are the snippets that S&P release to the market via its website.

The specific documents you should look for are the monthly “Inside the Index” publication, which will highlight the top five upgrades and downgrades in regards to index weighting changes for the S&P/ASX 200. The alternative is to read the “Fact Sheet” in the Australian indices section of the website. This quarterly list shows the top 10 in terms of index weighting. The unfortunate thing is that this is only attainable for the S&P/ASX 50 and 200 indices, and excludes the majority of other companies that make up the index.

Elio D'Amato is a director of Lincoln Indicators and head of the Stock Doctor Research.