 has posted double digit returns, which on the surface looks really great. But then you look under the hood a little bit and what you're finding is because the S&P 500 is what's called a market cap weighted index, which means that the bigger that the stocks are in that index, they have more pull on how the index performs. When you look at some of these stocks, what you're finding is six or seven of the stocks are responsible for the majority of the index's growth.