Last night Matt Cutts announced via Twitter that Google has begun to roll out a new algorithm update; Panda 4.0.

This is now the 26th update from Google under the name ‘Panda’, and is designed to knock websites that have certain low-quality content. The result of this has formed both “winners” and “losers” in the rankings as various sites have moved up and down Google’s search engine results pages.

Panda updates are usually rolled out monthly, and are mostly considered to be minor tweaks and adjustments. But, it seems that this update is a of a bigger variety, one that’s a major update to their core algorithm (rather than just a data refresh). Talking to Google, it sounds as if this update will be gentler for some sites and will lay the groundwork for future changes in that direction.

The update will affect different languages to different degrees. For example, in English, around 7.5% of queries will be affected to a degree that regular users might notice.

eBay is considered to be a big loser due to this update. Here is a list of top websites from Searchmetrics (image by Search Engine Land) which have been affected –

panda-4-loser

Lists like this are never perfect; the sites above may have experienced these drops due to other factors. The only real way for you to see whether you’ve dropped in the rankings is to check your search-drive traffic from Google, rather than particular rankings. Seen a significant increase? You’ve probably been rewarded by it (lucky you!), and a big decrease? You’ve probably been hit.

Here’s a list of all the Panda updates Google has made to their algorithm:

Panda Update 1, Feb. 24, 2011 (11.8% of queries; announced; English in US only)
Panda Update 2, April 11, 2011 (2% of queries; announced; rolled out in English internationally)
Panda Update 3, May 10, 2011 (no change given; confirmed, not announced)
Panda Update 4, June 16, 2011 (no change given; confirmed, not announced)
Panda Update 5, July 23, 2011 (no change given; confirmed, not announced)
Panda Update 6, Aug. 12, 2011 (6-9% of queries in many non-English languages; announced)
Panda Update 7, Sept. 28, 2011 (no change given; confirmed, not announced)
Panda Update 8, Oct. 19, 2011 (about 2% of queries; belatedly confirmed)
Panda Update 9, Nov. 18, 2011: (less than 1% of queries; announced)
Panda Update 10, Jan. 18, 2012 (no change given; confirmed, not announced)
Panda Update 11, Feb. 27, 2012 (no change given; announced)
Panda Update 12, March 23, 2012 (about 1.6% of queries impacted; announced)
Panda Update 13, April 19, 2012 (no change given; belatedly revealed)
Panda Update 14, April 27, 2012: (no change given; confirmed; first update within days of another)
Panda Update 15, June 9, 2012: (1% of queries; belatedly announced)
Panda Update 16, June 25, 2012: (about 1% of queries; announced)
Panda Update 17, July 24, 2012:(about 1% of queries; announced)
Panda Update 18, Aug. 20, 2012: (about 1% of queries; belatedly announced)
Panda Update 19, Sept. 18, 2012: (less than 0.7% of queries; announced)
Panda Update 20 , Sept. 27, 2012 (2.4% English queries, impacted, belatedly announced
Panda Update 21, Nov. 5, 2012 (1.1% of English-language queries in US; 0.4% worldwide; confirmed, not announced)
Panda Update 22, Nov. 21, 2012 (0.8% of English queries were affected; confirmed, not announced)
Panda Update 23, Dec. 21, 2012 (1.3% of English queries were affected; confirmed, announced)
Panda Update 24, Jan. 22, 2013 (1.2% of English queries were affected; confirmed, announced)
Panda Update 25, March 15, 2013 (confirmed as coming; not confirmed as having happened)