Explanation : *) There are two types of ranking factors that links pass on, trust and semantic power. Trust means that a website has vouched for you, it passes on from any type of link that is ********, it's the basis of algorithms. Semantic means meaning or information. As you've all known already, Semantic power, a word that you don't use on this forum, comes mainly from sources such as Wikipedia, social bookmarks and so on. You can't say it doesn't pass any link juice, because a site with more semantic power will rank higher than a site with less Semantic power assuming everything else is the same. *) There are three types of structures that we can categorise all websites in : giving, receiving and just a normal website. The giving structure gives out all of it's semantic power and trust from it's homepage onto it's internal pages. Because the homepage doesn't have any semantic power left, it receives a "compensation" from Search engines, extra trust. So that it can rank for all the keywords that it has in the menu that lead to internal pages, otherwise it would be at the bottom of every SERP with 0 semantic power and 0 trust. The receiving structure takes in all the semantic power and a bit of trust from it's internal pages, it's loaded with semantic power. *) Trust and semantic power in the eyes of search engines don't have a big difference, that's why the homepage of a giving structure website will rank approximately the same as the homepage of a receiving structure website. Semantic power can not be given away, it can't be shared, if you give it away it will get multiplied, but it can't be exploited. *) When the first update happens after both of the sites launch, the website with the giving structure website ( site 2 ) receives semantic power through a link from the website with the receiving( site 1 ) structure. Because the giving structure website( site 2 ) now has compensation trust + semantic power that it received from the receiving structure website site 1 multiplied together, it now ranks higher for it's keyword. Because the giving structure website( site 2 ) now ranks higher through the extra semantic power that it received from the receiving structure website : technically the receiving structure website( site 1 ) has now given/shared away it's semantic power and now receives bonus compensation trust from Google, that's where all the magic amplification happens. The next update the receiving structure website( site 1 ) will rank higher than the giving structure website( site 2 ), Google will once again give bonus trust onto the giving structure website( site 2 ) which will rank higher again than the receiving structure website( site 1 ). And this will go on and on in a continuous update cycle. This update cycle keeps adding bonus trust to both of the websites, to one website per update. This cycle is not lineair and will not continue infinetely, however it does give a huge boost, approximately amplification of 5-10 times. With time the variations will "stabilize".