This study explores the elusive social dimension of quantitative finance. We conducted three years of observations in the derivatives trading room of a major investment bank. We found that traders use models to translate stock prices into estimates of what their rivals think. Traders use these estimates to look out for possible errors in their own models. We found that this practice, reflexive modeling, enhances returns by turning prices into a vehicle for distributed cognition. But it also induces a dangerous form of cognitive interdependence: when enough traders overlook a key issue, their positions give misplaced reassurance to those traders that think similarly, disrupting their reflexive processes. In cases lacking diversity, dissonance thus gives way to resonance. Our analysis demonstrates how practices born in caution can lead to overconfidence and collective failure. We contribute to economic sociology by developing a socio-technical account that grapples with the new forms of sociality introduced by financial models -dissembedded yet entangled; anonymous yet collective; impersonal yet, nevertheless, emphatically social.
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From Dissonance to ResonanceThe Risk of Resonance: Cognitive Interdependence in Quantitative FinanceAs the term "financial engineer" suggests, the recent history of finance is part of the broader rise in systems engineering over the last half of the 20 th Century.Models, computers, and electronics have reshaped Wall Street as much as the jet engine changed aviation. Whether in industrial engineering or in financial engineering, the new tools of practice have proven faster, bolder, and more complex, opening up the scope for gains in speed, efficiency, and power. But they have also opened up the possibility of disasters. Indeed, it is no coincidence that a new body of expertise, cybernetics, was developed to deal with the complexities of advanced technological systems in the age of machine intelligence. Writing in the aftermath of one of the most automated (and lethal) wars to date, Weiner (1948), McCulloch andPitts (1943) andVon Foerster (1958) laid out the principles for the governance of systems marked by interdependencies and positive feedback. But whereas these concerns arguably helped system engineers limit (though not eliminate) the dangers of nuclear accidents or massive air traffic fatalities, the equivalent has not yet been developed for financial engineering. "Systemic risk," "circuit breakers," and related expressions populate the day-to-day parlance of regulators, but existing theories of the market do not explicitly focus on the interdependencies caused by financial modeling.Positive feedback, tight coupling, or lock-in hang menacingly over the portfolios of investors. As the credit crisis of 2008 comes to show, the large technological systems at the core of the industrial economy may be better prepared for the risks of complex engineering than modern finance. way that allows market participants to think collectively about the issue.Our study further demonstrates t...