What is the importance of Big Brand Preference in SEO factor?
Google in its new algorithm gives more push and preference to Big Brand networks in the search results.
Matt Cutts refer this "Big Brand Preference" as a minor change, rather than the update.
Google is not pushing up the big brands in its search results simply but it is also about factors like trust, quality, PageRank and other metrics which big brands would possess more better than the small ones.