Penguin 2.1 (#5) — October 4, 2013
After a 4-1/2 month gap, Google launched another Penguin update. Given the 2.1 designation, this was probably a data update (primarily) and not a major change to the Penguin algorithm. The overall impact seemed to be moderate, although some webmasters reported being hit hard.
Hummingbird — August 20, 2013
Announced on September 26th, Google suggested that the "Hummingbird" update rolled out about a month earlier. Our best guess ties it to a MozCast spike on August 20th and many reports of flux from August 20-22. Hummingbird has been compared to Caffeine, and seems to be a core algorithm update that may power changes to semantic search and the Knowledge Graph for months to come.
In-depth Articles — August 6, 2013
Google added a new type of news result called "in-depth articles", dedicated to more evergreen, long-form content. At launch, it included links to three articles, and appeared across about 3% of the searches that MozCast tracks.
In-depth articles in search results (Google)
Unnamed Update — July 26, 2013
MozCast tracked a large Friday spike (105° F), with other sources showing significant activity over the weekend. Google has not confirmed this update.
MozCast Update (Google+)
Knowledge Graph Expansion — July 19, 2013
Seemingly overnight, queries with Knowledge Graph (KG) entries expanded by more than half (+50.4%) across the MozCast data set, with more than a quarter of all searches showing some kind of KG entry.
Panda Recovery — July 18, 2013
Google confirmed a Panda update, but it was unclear whether this was one of the 10-day rolling updates or something new. The implication was that this was algorithmic and may have "softened" some previous Panda penalties.
Multi-Week Update — June 27, 2013
Google's Matt Cutts tweeted a reply suggesting a "multi-week" algorithm update between roughly June 12th and "the week after July 4th". The nature of the update was unclear, but there was massive rankings volatility during that time period, peaking on June 27th (according to MozCast data). It appears that Google may have been testing some changes that were later rolled back.
Panda Dance — June 11, 2013
While not an actual Panda update, Matt Cutts made an important clarification at SMX Advanced, suggesting that Panda was still updating monthly, but each update rolled out over about 10 days. This was not the "everflux" many people had expected after Panda #25.
"Payday Loan" Update — June 11, 2013
Google announced a targeted algorithm update to take on niches with notoriously spammy results, specifically mentioning payday loans and porn. The update was announced on June 11th, but Matt Cutts suggested it would roll out over a 1-2 month period.
Penguin 2.0 (#4) — May 22, 2013
After months of speculation bordering on hype, the 4th Penguin update (dubbed "2.0" by Google) arrived with only moderate impact. The exact nature of the changes were unclear, but some evidence suggested that Penguin 2.0 was more finely targeted to the page level.
Domain Crowding — May 21, 2013
Google released an update to control domain crowding/diversity deep in the SERPs (pages 2+). The timing was unclear, but it seemed to roll out just prior to Penguin 2.0 in the US and possibly the same day internationally.
Google Domain Crowding Update: May 2013 (High Position)
Google Domain Clustering Update (Justin Briggs)
"Phantom" — May 9, 2013
In the period around May 9th, there were many reports of an algorithm update (also verified by high MozCast activity). The exact nature of this update was unknown, but many sites reported significant traffic loss.
Panda #25 — March 14, 2013
Matt Cutts pre-announced a Panda update at SMX West, and suggested it would be the last update before Panda was integrated into the core algorithm. The exact date was unconfirmed, but MozCast data suggests 3/13-3/14.
Panda #24 — January 22, 2013
Google announced its first official update of 2013, claiming 1.2% of queries affected. This did not seem related to talk of an update around 1/17-18 (which Google did not confirm).