Membership in the S&P 500 is determined by committee, but the methodology can be reviewed here: http://us.spindices.com/documents/methodologies/methodology-sp-u

Membership in the S&P 500 is determined by committee, but the methodology can be reviewed here: http://us.spindices.com/documents/methodologies/methodology-sp-us-indices.pdf http://us.spindices.com/documents/methodologies/methodology-... Wikipedia says: Limitations on types of securities: > Securities that are ineligible for inclusion in the index are limited partnerships, master limited partnerships, OTC bulletin board issues, closed-end funds, ETFs, ETNs, royalty trusts, tracking stocks, preferred stock, unit trusts, equity warrants, convertible bonds, investment trusts, ADRs, ADSs and MLP IT units Limitations on exchanges: > The securities must be publicly listed on either the NYSE or NASDAQ. And of course the actual selection criteria is even more elaborate.