Back in the days when the RandCam furore was topical I wrote to the WTS and asked for their comments. They denied holding stock in the Company . The letter was on line (on this site and others)
Now? I believe that they need to be more careful as to the source of any income from trusts or donated shares , if they want to avoid criticism . However, having read this article in the November 2015 Wt..
http://www.jw.org/en/publications/magazines/w20151115/donations-worldwide-work/
It seems they are happy to take it from where they can get it, from a child's ice cream money up to a multi million dollar trust fund!