Another domain diversity update was confirmed by Google last week.
In addition to already trying to reduce domain crowding in SERPS by having at least one similar algorithm update already and recently reducing the number of search results for branded terms to 7 (as I reported a week or so ago) Google is really trying to prevent sites from dominating page 1 organically. I think more so its aimed at whittling out aggregators in preference of brand owners who may have 2 or more pages ranked for the same search query which may reduce the ability of the brand to receive traffic. Im especially convinced that ‘domain diversity’ is less applicable to non branded terms as a search for a branded term e.g. ‘marriott london’ returns just 1 non marriott.co.uk page on page 1 of the organic search results.