Dick Costolo: Twitter unfollows the leader as social milestones are missed

Slowing growth in user numbers and failure to capture a bigger slice of digital advertising revenue behind departure of the chief executive

It says something about the extraordinary scale of social platforms when a technology behemoth with 302m active users every month can be seen as failing to achieve its potential. Yet that is exactly why it appears that Twitter's chief executive, Dick Costolo, now has to go from the company's top post.

Related: Twitter's outspoken CEO Dick Costolo to step down