Google has announced that they have rolled out a new iteration of their original Panda algorithm update. Matt Cutts has made the following announcement via Twitter.
Google is rolling out our Panda 4.0 update starting today.
— Matt Cutts (@mattcutts) May 20, 2014
Our internal tool SERPent detects fluctuations & turbulence in Google algorithm in specific UK market sectors, we measure fluctuations based on a delta of 0-30 degrees, 30 being the highest degree of fluctuation.
SERPent shows that among many others, the following sectors have been affected the most by Panda 4.0:
Following are timelines of some sectors highlighted above.
Based on our data, Panda 4.0 looks like major algorithm update instead of data refresh. This means that Google has probably made significant changes to how Panda identifies sites.