The average stock in the S&P 1500 (a combination of large-caps, mid-caps, and small-caps) is down 2.71% already in October. The chart below shows that the smaller the stock, the worse performance has been.
We broke the S&P 1500 into deciles based on market cap at the start of the month — decile 1 contains the 150 largest stocks in the index, decile 2 contains the next 150 largest, and so on and so forth. We then calculated the average performance of the stocks in each decile so far in October.
With the exception of deciles 6 and 7, the average performance gets worse and worse as you move from the deciles of largest stocks down to the deciles of smallest stocks.
The 150 largest stocks in the S&P 1500 are only down an average of 0.45% so far in October, while the 150 smallest stocks are down an average of 4.25%!