I am seeing chatter within the SEO community throughout the past 24 hours and many of the automated Google tracking tools seem to be corroborating with that chatter that there may have been a Google update yesterday. Now, Google has not confirmed this update - so it is likely not a core update but might be something else going on.
Google likes to confirm those core updates and I assume that since they didn't pre-announce anything there that this is not a core update. Could it be a tweak to the June core update? Possibly or it can be a completely different Google algorithm update that Google does not want to talk about. It can also be something search spam related impacting a specific set of factors or it can be a bug with Google or a batch of sites.
I don't know yet - it is way too early. Right now, I am seeing a nice surge in chatter within the industry within WebmasterWorld and some in Black Hat World. Here is some of that chatter:
Yes an update is rolling out, I'm down -15% in today's update.
I'm seeing the same here, I was down about 15% yesterday and it's looking worse for today.
More drops for anyone today? Another 10% drop here
-10% today
I am seeing big changes in the SERPs now. I see what feels like an update is underway OR at least some kind of tweaks.
Here are screen shots from the automated Google ranking checkers:
Do you see ranking changes and Google organic search traffic changes over the past 24 hours or so?
Forum discussion at WebmasterWorld.