One of the biggest challenges in protecting privacy is that many of the violations are invisible. For example, you might have bought a product from an online retailer—something most of us have done. But what the retailer doesn’t tell you is that it then turned around and sold or transferred information about your purchase to a “data broker”—a company that exists purely to collect your information, package it and sell it to yet another buyer. The trail disappears before you even know there is a trail. Right now, all of these secondary markets for your information exist in a shadow economy that’s largely unchecked—out of sight of consumers, regulators and lawmakers.

http://time.com/collection/davos-2019/5502591/tim-cook-data-privacy/