Market Breadth Primer: Detective ToolsBy
Here is an example how to search for these records online.
Find The Press Release Agency
From the index owner website, you can always find their press release section. By checking out those press releases you can figure out which company works for them as the press release agency. It is really that simple.
For example, Standard & Poor’s uses PR Newswire for its press releases.
Since change of index components has to be announced before the actual change happens, and that the announcement has to be made public, press release is the only route to make such official announcements. The press release agencies always keep track of all the press releases they have processed because it is also a matter of legality for many public announcements.
If you can track down the press releases of the component changes of a particular index, you can reconstruct the historical component lists for the index.
Search With Google
You may hate google because it tracks your personal activities online but it is also very good at saving everything online.
Once you have seen how a company does its component change press release, it seldom changes. Hence we can pull out all the press releases easily like this:
First part of the query above in double quote forces google to look for the exact text within the quote as if it is a single item. Second part of the query started with +site enforces results from the website prnewswire.com only.
The date range you see there is done through clicking the "search tools" button to enable extra search filters. One of them is the date filter. This allows you to zoom in to specific records coming from that period of time only.
Back Tracking The Changes From Known Good Component Lists
You can find good copies of the component lists from various organizations.
CBOE is a good source as it states clearly the date for which the component lists are valid because they actually provide the weighting and other information too. Since CBOE is the exchange with many listed index options, it is a very good reference website to obtain correct component lists. The downside is that they are not as up-to-date as other sources.
Many free sources online are not reliable for the component lists on many market indices. The main problem is that many free websites are not maintained after a year or two. The ones at wikipedia.org so far are doing okay but the older lists from them from past several years are not that reliable. I see that they have a new project going on that work on financial data and related information. If this initiative grows stronger overtime, we may have a decent independent source for good financial data in the future.
If you are interested in constructing hard to find historical snapshots of component lists on various indices, you now know what can be done to track down the changes and get the job done yourself.
Notice that owners of many indices like to make money off their historical records. If you obtained the information from these organizations by paying for the data, you may not have the right to redistribute the information. Your payment only gives you the right to use the information yourself or within your organization.
If you reconstruct the historical component lists yourself from public record, it is your version of the history. It may not be completely correct but it is not subjected to the limitations imposed on you if you go to the source. It is one of those trade-off scenarios you have to be aware of.
I collect my own snapshots of the components on various indices from public information. This allows me to use the data I collected anyway I see fit. I feel more comfortable going this route.