I never understood it on "normal" words because it's obviously possessive but I was guilty of this on acronyms.
Then decided that wasn't right and just stopped using an apostrophe but of course the "s" still has to be lower case or it looks like part of the acronym.
Just today I got off my digital butt and searched it, apparently it's supposed to be like plural possessive with an s THEN apostrophe. I'm not sure I've ever actually seen this applied in real life, or maybe I just overlooked it when I did.
According to this, plural of NGO would be NGOs'
Answer (1 of 3): Thanks. This is really a question about the use of the apostrophe. The main use of the apostrophe combined with final “s” in English is to show ownership or origin. “’s" conveys the meaning “belonging to" for a single noun whilst “s'” coveys belonging to a plural noun. So “my b...
www.quora.com
But this was just a poster responding to the question so I wonder if they're really correct???