The below chart has been making the rounds on Twitter. It shows the percentage of the S&P 500 market cap which is held by the top 5 biggest stocks in the S&P 500. Currently the concentration in these five stocks is at 19%. This is not a record percentage as this percentage has been much higher in the past.
Currently these five stocks are: Microsoft, Apple, Amazon, Google & Facebook.
If you zoom in on just the two biggest stocks by market cap (Microsoft and Apple) the percentage of these two in the S&P 500 is almost 10%.
However, this chart shows that this concentration in just five stocks has been much higher in the past. In the 1960’s concentration was above 25%.