This chapter delves into the issue of the legal qualification of data within property law, which gives rise to a remarkable paradox. On the one hand, it is a fact that a rapidly growing number of companies have discovered the (potential) economic value of data and have come to consider, use and treat them as regular business assets. As a result, data are gathered, processed, analyzed and also ‘sold’ on a large scale and on a daily basis. On the other hand, the author shows that – taking the example of Belgian law – that property law denies the very existence of data files. They are not susceptible to a right of pledge or attachment. The chapter looks at the indirect way in which it is possible to pledge and attach data files by way of the data carrier, the sui generis database right, and also discusses alternatives. Moreover, the chapter also looks at whether pledging of and foreclosure on data files can be considered a justified processing of personal data in light of the GDPR.