SEO folks: we recently launched a refresh of this algorithm: http://t.co/KKSXm8FqZW Visible to outside world on ~Feb. 6th.If you observed a change in organic search ranking or traffic of your webpage last week, this may be the result of Google’s updated Page Layout Algorithm. Google introduced the page layout algorithm in January 2012, and updated it in October 2012.Now on Feb. 6, 2014. This is also known as Top Heavy Algorithm.
— Matt Cutts (@mattcutts) February 10, 2014
This update demotes the ranking of those webpage having too many ads ads on the top and if the ads are distracting to users.
As for what the page layout algorithm was specifically targeting, a lot of people are speculating that it might be affecting websites that seem to utilize the endless scrolling technique, and often with a lot of white space and larger than normal font size. It’s becoming more common in news websites, but the trend has been moving to regular sites.