US Stock Market Concentration
$SPX 
Top 6 components are 22.1% of SPX Market Cap
Top 10 Components are 27.7% of SPX Market Cap
Leaving the 1999 Peaks in the dust

Top 40 = 50% today, but was 55% in 1999
Which IMO Makes today more complicated https://t.co/SQMEd5lGNR