The Semiotic Infrastructure of Financial Markets

This thesis sheds light on the valuation practices of financial market participants in three stages. First, a socio-historical approach outlines the conditions in which market participants operate today. The scope of buying and selling decisions has been amplified by the computerization of markets. These decisions are also increasingly taken on by a particular type of actor, due to the "asset management revolution". Secondly, the valuation practices of market participants are clarified through an analysis of the main valuation supports used: the Bloomberg Terminal, stock market indices, central bank announcements and oil benchmarks. The influence of these supports was sometimes recognized, but the context of their emergence and the modalities of this influence remained poorly identified. Thirdly, we draw out some of the implications of the power of these valuation tools for the functioning of financial markets. Produced by a handful of financial information companies, the conventions studied give these companies a quasi-regulatory role in the markets. This other facet of financial regulation, less visible than legislation, cannot be ignored in reform proposals aimed at making markets more stable or sustainable.