What is the best datasource for historical lists of S&P500, NASDAQ100 constituents? http://en.wikipedia.org/wiki/List_of_S&P_500_companies link shows current S&P500 constituents. Also, there is another table in the bottom named : "Recent changes to the list of S&P 500 Components" which shows additions/deletions into S&P500 from 2009 onwards. Where can i find the accurate data for last 10-20 years? If it is available for free, that will be great! Thanks. EDIT: If I can get historical lists for Russel 2000, 3000 that will be even better!