Negative signal on advertisers: In an attempt to rein in some of the outrage around the way Facebook harvests data from users and sells it, Zuckerberg also announced he would end the “Partner Categories” program that allows advertisers to target users based on their own third-party data. It’s likely that Partner Categories was not a big business for Facebook, but nonetheless it still represents a pulling-in of the horns.
http://www.businessinsider.com/the-end-of-facebook-2018-3
origin - http://www.pipiscrew.com/?p=13268 no-one-thinks-this-is-the-end-of-facebook-yet-investors-sense-blood-in-the-water