Finance has traditionally been conceptualized on the basis of what could be labelled a credit model. This model theorizes finance as a functional actor in the process of capitalist accumulation. This structural model has entertained a specific understanding of the contradictions of finance which emphasizes the imbalances in its relation to production. While the rich literature based on this template has generated important insights for understanding capitalist finance, it is debatable whether the credit model is sufficient to account for financial speculation. This article argues that the perception that speculation is essentially based on irrational optimism fails to capture what is important about recent developments of finance. New conceptual foundations are required, in order to develop a political economy of speculation which examines the way in which speculation is socially constructed, how it evolves through history and whether or not it is transforming the nature of capital accumulation.