Over the weekend I spotted that Google seem to be testing expandable sitelinks for certain websites when you search for their brands. This trial allows users to easily navigate to top-level areas of a site straight from the SERP without needing to go through that site’s navigation.
We know Google tends to test a lot when it comes to mobile and this makes sense when you consider how much they are championing superior mobile experiences and speedy browsing.
From my initial research I can’t see any reason why some websites would have this and why some wouldn’t. Looking at some of the expanded site links in detail makes it look like that currently Google are deciding on the sitelinks with little input from webmasters. I’ve reached out to Gary Illyes from Google for comment and will keep this post updated with any response.