In Writing Advice: Meryn Stol voted up this answer. Joshua Engel "Has been" is present perfect. It means that, from the point of view of right now, the action is completed. "Had been" is past perfect. It means that, from the point of view of some time in the past, the action was completed. That is, you could say, "By 1998, X had acquired Y". But you can't say, "By 1998, X has acquired Y". The past perfect is used to describe events in the farther past from the point of view of the nearer past. See question on Quora - Meryn Stol