$SPY market cap is 70-80% of total US stock market capitalization

5 Companies ( $MSFT, $AAPL, $AMZN, $FB, &amp; $GOOG) make up over 22% of the index

Breakdown 👇 
https://t.co/YDBh0Qg3X5 https://t.co/eAOYwFMjWO