The 21 day plunge into the May 25 low caused significant technical damage to the SP500. Specifically, it caused the quarterly moving average to roll over and slope down. The bearish slope indicates a potential shift in trend from bull to bear.
During the bear mkt of 2007-2009, dead cat bear mkt bounces typically lasted 18 to 34 days. That includes the 22 day rally into Dec 26 2007, the 18 day rally into Aug 11 2009, and the 32 day rally into Jan 6.
Now, in stock mkt bull cycles, bullish impulses “right translate” and left translate in bear markets. Let me explain. Cycles are measured from low to low. The last low to low cycle was 77 days ~ from Feb 5 to May 25. The final low to low into the March 6 2009 capitulation was 75 days. Using the last 77 day low to low cycle as our starting point, for this dead cat bounce to right translate, it would have to rally 39 days or more off the May 25 low. Now, as we noted in the typical dead cat bounces in the last bear mkt expire 18 to 34 days later.