At the same time, beginning Friday 19 February, it will now only show ads at the top and bottom of the SERP. Although it may increase the number of ads from three to four if the search query is “highly commercial.”
This roll-out will effect users worldwide in all languages and will bring the desktop experience closer to the mobile experience, although whether the amount of ads shown to mobile users will increase hasn’t been confirmed.
so why limit the amount of space for advertisers on its SERPs?
According to The Media Image the reason for this may well be because “Google has determined the average click-through-rate for Right Hand Side Ads is poor across verticals, and the expected CPC inflation from this major change is projected to more profitable in the long run.”
The “complete and permanent” roll-out will be finalized on 22 February.