This article analyzes stock valuation practices, based on participant observation in a brokerage company in New York and in an asset management company in Paris between 2002 and 2004. Financial analysts, traders, sales people and fund managers all use the same financial theory, by following standardized procedures, according to which "value", defined differently by each profession, is always problematized in relation to its "truth". Acting in the name of real or potential clients whose interests they are supposed to represent, employees position themselves as "investors" whose interactions would ensue in the creation of "efficient markets". Employees are bound by relations of competition and complementarity, which are articulated in particular through technical debates about the different definitions of what constitutes the "truth of value". Yet, just like financial regulation does, they also mobilize arguments according to which the "truth" that would be reflected in prices, is part of a political project in which the financial industry, as the social space of "qualified investors", is expected to constitute "efficient markets" in order to obtain an "optimal" social allocation of credit. Thus, the financial industry is expected to produce a "truth" in prices, which is both technical and political.
