The ETF symbol SPY is the granddaddy of them all. It’s the oldest, most heavily-traded, and best-known. There is a very similar fund, however, with the symbol RSP, which also represents the S&P 500. Its difference, however, is that its calculation is based on the equal-weighted S&P 500, as opposed to the “normal” S&P which heavily favors the mega-caps.
As shown in the chart above, the SPY (blue line) has massively outperformed the RSP (black line) over the past couple of years. This simple difference in weighting yields about a two-fold difference in performance, because the mega-caps are carrying so much weight.
