(Re-) assembling the gilt-edged market : quantification, model misfire, and the politics of expertise in post war Britain

Abstract

This article explores the contested (re)-assembly of the UK gilt-edged market between the 1950s and 1980s, foregrounding the ever-shifting process of quantification in stockbroking firms that made and remade the market. Drawing on archival materials and oral history interviews, it first traces the consolidation of sociotechnical agencements, made up of actuaries, yield models and quantified evaluation practices in stockbroking research departments, which gained authority as investment became increasingly institutionalised. These calculative agencements reshaped trading practices, but were also subject to resistance, misfire, and rivalry as alternative, more formalised models were proposed. While actuarial authority was eventually displaced by ‘financial economics’ expertise, established valuation devices proved durable by being reconfigured and repurposed within new professional and institutional settings. The paper argues that the durability and performative capacity of models rest on their ontological mouldability: their capacity to be translated across successive regimes of expertise and institutional contexts while retaining practical relevance. The article contributes to recent scholarship in the Social Studies of Finance on performativity and post-performativity that emphasises the political, fragile, and historically situated nature of financial markets.