In the era of digital markets, companies are able to collect an unprecedented amount of personal information about their customers. With big data increasingly being employed in all areas of the economy, competition authorities face the question of how prominently data are to feature in competition cases. Data has played a role in a number of recent merger decisions, such as the Facebook/Whatsapp case, Google/DoubleClick case and Microsoft/Linkedin case, as well as in the recent Bundeskartellamt’s abuse of dominance investigation into Facebook.