Capitalization of the S&P 500

Here is a good link to the capitalization of the S&P 500 showing the companies with the highest and lowest weightings. The top 20 XOM GE MSFT C T BAC CVX PG CSCO JNJ AIG PFE JPM IBM MO INTC COP HPQ VZ AAPL are a combined 30.18% of the index. So if you can see what these stocks are up to pre market, you will have a good idea where the S&P is going. The top 100 stocks make up 64.27 % of the index.