Things aren't going well for Fitbit (NYSE: FIT) shares today following a downgrade from Stifel Nicolaus analyst Jim Duffy, who dropped his rating on Fitbit shares from hold to sell. The analyst's price target of $6 was unchanged, suggesting the move could be in response to shares rising over the past three months.It's been a tough year for the fitness company, and the situation may only get worse in 2018, in Duffy's view.Image source: Fitbit.Continue reading