The average stock in the S&P 500 is down 4.61% over the last two days. We wanted to see how a stock's performance during the 8%+ rally from 8/22 to 8/31 has impacted performance since 8/31. To do this, we broke the S&P 500 into deciles (10 groups of 50 stocks each) based on performance during the rally, and then calculated the average performance of stocks in each deciles during the current 2-day selloff.
As shown below (click to enlarge), the better a stock performed during the rally, the more it has gone down during the pullback. The 50 stocks that went up the most from 8/22 to 8/31 are down an average of 6.40% since 8/31. Conversely, the 50 stocks that went up the least from 8/22 to 8/31 are only down an average of 2.28%. Investors have clearly been selling their winners over the past few days.