Invesco S&P 500 Equal Weight ETF changes the dynamics of the S&P 500 index in an important way. The biggest reason to buy Invesco S&P 500 Equal Weight ETF (RSP 0.47%) is contained in the exchange traded fund's (ETF) name. That said, there's more to the story here than meets the eye. Here are three reasons why, if you are considering buying an S&P 500 (^GSPC -0.59%) index clone, you might be better off buying this Invesco ETF like there's no tomorrow instead. 1. Equal weighting matters theoretically and prac ...