While the ownership may not be anti-GOP the rank and file journalists are.
The overwhelming majority admit they vote Democrat and have for years/decades.
They claim they set aside personal feelings and don't let it intrude into their reporting but I find this harder to believe.
I believe major Hollywood studios are also owned by major corporations.
By your logic Hollywood actors would be pro-GOP. While there are a few that are, the overwhelming majority of opinions that come out of Hollywood are left leaning.