Facebook (of all places!) is one of the few companies that makes this transparent. If you have a Facebook account, and live in GDPR-land, go check which compan

Facebook (of all places!) is one of the few companies that makes this transparent. If you have a Facebook account, and live in GDPR-land, go check which companies illegally passed on your data (https://www.facebook.com/adpreferences/ad_settings https://www.facebook.com/adpreferences/ad_settings -> Audience based advertising) and report them!