Anyone recall study less than 10% of companies produce90% of market return?

[wescobrk]

I remember reading this a couple of years ago but I didn't write down the source.

Does anyone recall the source? Is it as something small as 4 or 5% of companies contributes more than 90% of return for S&P 500 for last several decades?

I did a quick search but couldn't find the source.

Thanks.

[Cigarbutt]

One can question methodology and holding-period returns at the individual level may make those studies irrelevant. This has been looked at along many variations of the same theme and here are two examples:

https://www.chase.com/content/dam/privatebanking/en/mobile/documents/eotm/eotm_2014_09_02_agonyescstasy.pdf

https://csinvesting.org/wp-content/uploads/2017/05/Bessembinder-Do-Stocks-Outperform-Treasury-Bills.pdf

 

The idea is that there is significant positive skewness with a far right-sided fat tail.

So, the returns have been concentrated among a select few and, interestingly, returns have continued to be concentrated within only a few days of the total holding period, with most or all return in the last few years (since the irrational exuberance speech in 1996) happening in the 24h before and after Fed policy public annoucements (typically 8 times a year).