Hayek and Fama are sometimes seen as proposing a comparable theory of prices. Hayek proposes to understand prices as information conveyer from the process of competition, while Fama defines efficiency as the fact that all information in a market is integrated in assets prices. This close up ignores huge differences between the authors. This paper explains how a lineage between Hayek and the theory of informational efficiency of Fama can be illustrated while taking into account these differences. We introduce in order to defend this claim a distinction between methodology and epistemology: methodology is seen as the way an author operationalizes his broader conceptions whereas epistemology is defined as the core conception of his theory. We particularly emphasise a homogeneous shift in the epistemology of Hayek and the theory of efficiency. We conclude that this shift gives a content to what some authors called neoliberalism as a form of Weltanshauung.