Possessive form for words ending in "y"

Which of the following is correct?

The fortune 500 companys' assets are vast.

The fortune 500 companies' assets are vast.


Solution 1:

I think this would clear things up:

  • This Fortune 500 company
  • This Fortune 500 company’s assets are vast
  • These Fortune 500 companies
  • These Fortune 500 companies’ assets are vast

Even though it’s possessive, it’s still pluralized in the normal way for nouns ending in -y.