Machine Spirits: Speculation and Adaptation of LLM Agents in Asset Markets

Fuente: arXiv
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Autores principales: Saxena, Maxime, Pangallo, Marco, Hommes, Cars, Caccioli, Fabio, del Rio-Chanona, R. Maria
Formato: Preprint
Publicado: 2026
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author Saxena, Maxime
Pangallo, Marco
Hommes, Cars
Caccioli, Fabio
del Rio-Chanona, R. Maria
author_facet Saxena, Maxime
Pangallo, Marco
Hommes, Cars
Caccioli, Fabio
del Rio-Chanona, R. Maria
contents As Large Language Models (LLMs) become increasingly integrated into financial systems, understanding their behavioural properties is crucial. Do LLMs conform to the rational expectations paradigm, do they exhibit human-like "animal spirits", or do they instead manifest distinct "machine spirits"? We investigate these questions with a simulated financial market, exploring the behaviour of 15 LLMs spanning a range of sizes, capabilities, and providers. Our results show that LLMs exhibit a spectrum of economic behaviours, from stable coordination on the fundamental value to human-like speculative bubbles. These behaviours are generally inconsistent with the rational expectations hypothesis. We also consider an ecology of heterogeneous agents, a more realistic setting compared to markets with identical LLM agents. These mixed markets can produce outcomes which vary substantially across repeated simulations. Even the most advanced models fail to consistently stabilise the market, with price bubbles sometimes forming despite only a minority of agents naturally forming bubbles. Instead, advanced models in mixed markets adapt their forecasting strategies to the behaviour of other agents. This adaptation can allow them to successfully exploit less sophisticated counterparts and achieve higher profits, but can also contribute to increased market volatility. These findings suggest that the introduction of AI agents into financial markets fundamentally reshapes their ecology. In particular, heterogeneous populations of LLMs can generate endogenous instability, while individual-level adaptation may amplify, rather than mitigate, market volatility.
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id arxiv_https___arxiv_org_abs_2604_18602
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Machine Spirits: Speculation and Adaptation of LLM Agents in Asset Markets
Saxena, Maxime
Pangallo, Marco
Hommes, Cars
Caccioli, Fabio
del Rio-Chanona, R. Maria
Trading and Market Microstructure
Computational Engineering, Finance, and Science
As Large Language Models (LLMs) become increasingly integrated into financial systems, understanding their behavioural properties is crucial. Do LLMs conform to the rational expectations paradigm, do they exhibit human-like "animal spirits", or do they instead manifest distinct "machine spirits"? We investigate these questions with a simulated financial market, exploring the behaviour of 15 LLMs spanning a range of sizes, capabilities, and providers. Our results show that LLMs exhibit a spectrum of economic behaviours, from stable coordination on the fundamental value to human-like speculative bubbles. These behaviours are generally inconsistent with the rational expectations hypothesis. We also consider an ecology of heterogeneous agents, a more realistic setting compared to markets with identical LLM agents. These mixed markets can produce outcomes which vary substantially across repeated simulations. Even the most advanced models fail to consistently stabilise the market, with price bubbles sometimes forming despite only a minority of agents naturally forming bubbles. Instead, advanced models in mixed markets adapt their forecasting strategies to the behaviour of other agents. This adaptation can allow them to successfully exploit less sophisticated counterparts and achieve higher profits, but can also contribute to increased market volatility. These findings suggest that the introduction of AI agents into financial markets fundamentally reshapes their ecology. In particular, heterogeneous populations of LLMs can generate endogenous instability, while individual-level adaptation may amplify, rather than mitigate, market volatility.
title Machine Spirits: Speculation and Adaptation of LLM Agents in Asset Markets
topic Trading and Market Microstructure
Computational Engineering, Finance, and Science
url https://arxiv.org/abs/2604.18602