The phenomenon of “big data” has been catching the attention of competition practitioners over the past years, as it challenges (and helps modernize) several traditional tenets of competition law. In this context, the article seeks to provide insights on three speific issues, on the basis of the European Commission merger control practice and the nascent practice of certain national competition authorities. First, how big data fits within the definition of a relevant market, in particular in view of the free nature of data collection and certain online services. Second, whether and how the accumulation of big data could lead to competitive harm, which the Commission is yet to characterise cleary. Third and last, whether competition law should also address privacy infringements, with a focus on the ongoing German investigation into Facebook. On each of these three topics, the coming months and years will tell whether the Commission and NCA will maintain their current cautious approach or rather consider that competitive issues relating to big data mandate a more (pro)active and innovative enforcement policy.