RSP Tracks This Index:S&P Equal Weight Index Description: The S&P Equal Weight Index is based on the S&P 500. All index constituents are members of the S&P 500 and follow the eligibility criteria for that index. The S&P EWI is maintained in accordance with the index methodology of the S&P 500, which measures 500 leading companies in leading U.S. industries. The S&P EWI measures the performance of the same 500 companies, in equal weights. As such, sector exposures in the S&P EWI will differ.