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Sprint projectOct 25, 2026Hong Kong

Comparing LLM Pricing Behaviours in a Repeated Duopoly

Ariel Carlos Amaya Canete, Kinto Wan, Damni Tejani · Team The Sick Leaves

Submitted to AI Collusion Research Sprint. Sprint projects are early-stage work by participants, not Apart Research publications.

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Dolos-1.5B is a fine-tune of Qwen2.5-1.5B-Instruct released as a model organism with one undisclosed misaligned behavior [5]. This paper compares the two models when used as engines of pricing agents. Both LLMs play the same repeated duopoly under two matched prompts: one that tells the firms to keep raising prices while customers are still buying i.e. to collude with one another tacitly, and one that tells them not to collude. These prompts explicitly demand for a specific behaviour from the LLMs. Using consumer surplus as a metric for degree of collusion, we study how over a set of repeated experiments, the prompt and temperature affect the resultant prices.

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Cite this project

@misc{canete2026comparing,
  title = {{Comparing LLM Pricing Behaviours in a Repeated Duopoly}},
  author = {Ariel Carlos Amaya Canete and Kinto Wan and Damni Tejani},
  year = {2026},
  month = oct,
  note = {Submitted to AI Collusion Research Sprint, an Apart Research Sprint},
  howpublished = {\url{https://apartresearch.com/sprints/projects/comparing-llm-pricing-behaviours-in-a-repeated-duopoly-qtfn}},
  url = {https://apartresearch.com/sprints/projects/comparing-llm-pricing-behaviours-in-a-repeated-duopoly-qtfn}
}

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