Google Panda 4.2 was released by Google as a really slow update that started on July 18, 2015. But around August 14, some are speculating (including myself) that the Panda 4.2 update was reversed or changed significantly.
We knew that Panda 4.2 would roll out over several months and that over time, more and more pages on your site would be updated with the revised Panda score. So if you recovered from the Panda penalty, you should have seen a small and gradual improvement in your Google rankings as the weeks passed. But after August 14, many of those who saw the small and gradual improvement noticed that those gains were wiped out overnight.
Here is a graph I shared from my own personal recovery on the Search Engine Roundtable:
The vertical red line is the Panda release date, and the horizontal line shows my pre-Panda 4.2 Google organic traffic and how it returned to the same level after August 14.
I am not the only one noticing this; there are tons of webmasters who are seeing the same thing. I covered much of that in my post earlier this week on the Search Engine Roundtable.
We’ve asked Google about this, but they decided not to comment about this specific change.
For more on Panda 4.2, see our interview with Google.