[ocdtrekkie]

2019 is far from a complete year.

In both 2017 and 2018, Alphabet is the first listed corporation[0], which is probably the reason I see the claim made, most of the rest are associations.

[0]If you ignore BC/BS, which is a "federation of 36 independent companies", though that is largely a way to deal with the law requiring health insurance be in-state. If you want to, I'd accept saying Alphabet is the second corporation on the list, if we're being real.