My opinion is that "of course" they are; but that this also poses a challenge to our pre-corporate notion (conceptualization) of personhood.
My chosen way to make sense of this is that corporations are a person of a type person that exists above the layer (or 'strata') in which typical individual humans are persons. I say 'above' because human individuals are one of the main 'ingredients' that come together to form corporate persons.
the picture is how there are 'personhoods' of (at least) two distinct layers or strata: individual and collective persons. So the human individuals come together to form corporate individuals, a sort of meta-person.
And I mean this very much in the sense of an egregore; the main difference being how earlier large bureaucracies would use papers and letters and such, but corporate bureaucracies are now fully digitized and using computers in networks.