There is a name for that loop on the back of your necktie: The Keeper.
As the necktie wends its way back into slightly-more-casual ensembles, its use provokes debate among partisans. (Postulate: for every style opinion x of magnitude y, there is an equal and opposite opinion -x of magnitude y.) To wit: Use or eschew(...s)?
Some like the look shown above, un-keepered, so that the two blades swing freely of one another. (Let me say again how much I love this suit/tie-shirt combination. Today is a day for parentheticals.) I like this approach in more casual settings. But for the office, especially when one is walking around hunched over a draft court filing, the cleaner lines of a keepered (kept?) necktie are the way to go.