GoogleAlgorithmConfirmed
Page Layout (Top Heavy)
Demotion for pages that pushed content below the fold with excessive above-the-fold advertising.
What changed
Google began demoting pages where a user had to scroll past a heavy block of advertising before reaching any real content. The change was announced publicly and refreshed periodically over the following years. Google's guidance pointed site owners at browser-size testing tools and advised that reasonable ad density above the fold was not a problem.
Timing
Rollout began 19 January 2012. No completion date was announced. Rankings typically remain unstable for the whole rollout window, so measurements taken inside it are not a reliable read on the outcome.