Studies of the ways in which the media report nanotechnologies, and particularly the ways in which they frame their interpretation, are crucial to an understanding of the formation of public perceptions of what are highly technical areas of scientific endeavour. This talk reports on a research project which, whilst broadly located within this area of concern, looked at the related question of the financial understanding of science: how, in a field characterised by high levels of commercialisation, potential investors get information and make judgments about particular applications, and the significance of the roles played by journalists and other mediators in this process. The focus here is on the practical epistemological strategies that scientific and financial journalists employ to make sense of nanotechnologies. Drawing on interview data, the paper considers the way that these journalists assess claims made about scientific validity and investment potential, and how they negotiate such narrative dilemmas as balancing the need for scepticism in a rhetorically inflated context with the professional requirement to produce an interesting story. It is argued that this analytic focus – on journalists as active interpreters and as actors for whom the understanding of nanotechnologies is a pressing practical problem – provides an important complement both to studies of the framing effects of journalistic copy, and to studies of public understandings of what remains, for most of the public, a relatively arcane field. Moreover, in focusing on where the action currently is, it may inform our knowledge of not just the commercial development of nanotechnologies, but also the formation and development of public opinion.