5
2024, was the largest stock in the S&P500 with an index weight of 6.98%. V.F. Corporaon as of
March 12
th
was the smallest stock in the S&P500 with an index weight of .01%. This meant that
at that me Microso, the largest stock, had 698 mes the weight of the smallest stock in the
index, demonstrang the sheer power that the largest stocks have in the index. Now while
obviously the largest stock might be much greater than the smallest stock, how would it
compare to the median stock, the 250
th
largest stock in the index? In this case, Electronic Arts
(EA), the 250th largest stock as of March 12
th
, had an index weight of .08%. Therefore, in this
case, Microso would sll possess 87.5 mes the weight of EA, demonstrang that this one
stock controls much more of the total return of the index than the enre boom half of the
index.
Through this paper’s analysis it was discovered that the S&P500 index is very top heavy,
as its largest 10 stocks in any given year between 2015 and 2023 accounted for, on average, 26%
of the total index’s market cap. This 26% is also not telling of the whole story either, as the top
ten stocks percentage increased throughout the 7-year period, with every year aer 2020
having a larger percentage than 26%. Figure 3 below depicts just this, as it shows the rankings of
the 10 largest stocks in the S&P500 as of January 1
st
, 2024, with these stocks collecvely holding
34.7% of the whole market cap of the index. This disparity between the top stocks in the index
can be seen even clearer when I also included the top 11-20 stocks. Between 2015 and the end
of 2023, on average, 36.9% of the index’s market cap resided within its top 20 stocks, with a
similar increasing percentage trend as seen with the top 10 stocks. This concentraon at the top
of the index leaves the remaining 480 or so stocks to have on average .13% of the index’s
market capitalizaon per stock. This disparity at the top is what led me to our queson in this