Abstract: Disclosed is a method of formulating a list of advertisements in an advertisement service. The method comprises analyzing a web content so as to identify a plurality of keywords therefrom, and retrieving data of a plurality of advertisements, each of which is associated with one of the plurality of keywords and is presently subject to an advertising service. The method further comprises processing the data of the plurality of advertisements so as to identify two or more advertisements that are associated with the same advertiser and further processing data of the two or more advertisements so as to identify at least one qualified advertisement for disfavoring in the advertising service. The method further comprises ordering at least part of the plurality of advertisements to display along with the web content such that the at least one qualified advertisement is disfavored in the ordering.