For example, a local car dealership can now show ads to people who are likely in the market for a new car who live near their dealership. To date, advertisers have been able to show ads to people based on their expressed interests on Facebook. Now with partner categories, they can also show ads to people on Facebook based on the products and brands they buy across both desktop and mobile.Facebook swears that no personal information is shared with the social network, third parties, or advertisers. It says that companies have used this type of targeting off of Facebook for years and that "partner categories work the same way all targeting on Facebook works."
While FBX on News Feed is great for advertisers and fantastic for Facebook, especially as it's under pressure to boost revenue, it's a risky maneuver that could remind users that they're always being watched. Consumer retargeted ads have been around for years, but it's the prime News Feed real estate that could throw some users off.