It appears they've been doing it since 2012: https://www.engadget.com/2016/12/30/facebook-buys-data-on-users-offline-habits-for-better-ads/ https://www.engadget

It appears they've been doing it since 2012: https://www.engadget.com/2016/12/30/facebook-buys-data-on-users-offline-habits-for-better-ads/ https://www.engadget.com/2016/12/30/facebook-buys-data-on-us... Assuming this is up-to-date this tells you who they buy from: https://www.facebook.com/help/494750870625830 https://www.facebook.com/help/494750870625830