Concentration in the Stock Market

CNBC had a piece this week that looked at how top heavy returns in the stock market have been this year. They showed 3 stocks — Amazon, Netflix and Microsoft — alone make up more than 70% of the gains in the S&P 500 and Nasdaq 100 indexes:

When you include Apple, Google (I refuse to call this company Alphabet), and Facebook those numbers jump to an absurdly high 98% and 105%, respectively.
The obvious ta…