Category talkAAA Corporations

I did a minor grammatical edit, but this portion  "If a Prime Megacorporation is a subsidiary of another corporation, this corporation receive AAA rating for practical reasons, and until the AAA subsidiary is sold, unless the parent company can justify sufficient size and an importance on its own (this is also true for AA or A rating)." is a little confusing and I'm not sure the best way to clean it up.  Any ideas?