On the day that GDPR comes into force, PI has launched a campaign investigating a range of data companies that make up a largely hidden data ecosystem. This hidden data ecosystem is comprised of thousands of non-consumer facing data companies - such as Acxiom, Criteo, Quantcast - that amass and exploit large amounts of personal data. Using the rights and obligations provided for within the new data privacy law, PI's campaign involves investigating a selection of these companies whose business…