Seems extreme, although it was a bad day for tech stocks anyway, so the portion of the drop attributable to the acquisition is surely smaller.
Anyway, the market seems to be communicating that not only does it think FB got bad value, but that this deal is bayesian evidence that it is being badly managed.
EDIT: I still don't think 100% of the decline is attributable to the broader market move, because TWTR and certainly KING should be more volatile than FB. But, yeah, the story might not be as clear as I thought.