There seems to be a Google update happening again. This one is not announced by Google and webmasters are relating it to the Bert update.
I personally have not seen any major changes on my field sites but many people are complaining about crappy websites ranking high.
Below are some screenshots taken from popular webmaster forums:
There is no clear information as yet if certain types of websites were affected. Do you see any changes to your websites?
Google does make algorithm changes and chances are that your website might gain or lose rankings.
If you have lost rankings and traffic, I would recommend not to panic and wait for few more days. A lot of such updates take days to roll out. And there are corrections made in few weeks as well.
Hence, just keep looking at your stats for a few weeks and do not make changes assuming that Google does not like your website anymore.