The promises of Big Data Analytics are grand and tempting. Access to the large pools of data, much of which is personal, is said to be vital if the Big Data initiatives are to succeed. The resulting rhetoric is of data sharing. This talk exposes ‘the other side’ of data sharing which often remains in the dark when the Information Industry and researchers advocate for more relaxed rules of data access and use: namely, the talk frames the issue of personal data use in terms of the commons, a resource shared by a group of appropriators and therefore subject to social dilemmas that have to be addressed if the resource use is to be sustainable. The talk will argue that the uncontrolled use of the data commons will ultimately result in a number of the commons problems, and elaborates on the two problems in particular: disempowerment of the individual visà- vis the Information Industry, and the enclosure of data by a few Information Industry actors.