Select all of the correct statements about the S P500 index.
1) The S&P500 index is weighted by market capitalization.
2) There are multiple ETFs that track the S&P500 index.
3) The S&P500 index is price-weighted.
4) The S&P500 index tends to focus on relatively large firms but inclusion in the index is not based exclusively on firm size.
5) The S&P500 index is equally-weighted.
6) The S&P500 index focuses on the very oldest firms.