Amazon has been fined 746 million euros by the data protection authority in Luxembourg.
The largest online retailer in the world announced the penalty already imposed on July 16 in its detailed quarterly report on Friday night.
The reason given by the CNPD is that Amazon has violated the European General Data Protection Regulation GDPR.
The European subsidiary of Amazon is based in Luxembourg.
Amazon denied the allegation and announced an appeal. "There was no personal data breach, and no customer information was disclosed to anyone," a spokesman said. "In terms of how we display relevant advertisements to customers, this decision by the CNPD is based on subjective and unchecked interpretations of European data protection law, and even with that interpretation, the intended fine is disproportionate."