ResearchResearch paperLarge Language Models · Business, Funding & Industry · Reinforcement Learning1 source · Oct 20, 2026

Understanding the Inner Workings of a State-Space Foundation Model for Limit Order Books

We find that, similarly to games where sequence models build an internal representation of the board, an 8.2M-parameter Mamba-3 state-space model trained autoregressively on the tokenized message stream of eight large-cap US equities learns an internal representation of the market and its dynamics.

Key points

  • Autoregressive foundation models offer state-of-the-art capabilities to simulate the market by generating the message flow of limit order books (LOBs).
  • This study therefore asks what these models actually learn about market microstructure.
  • In particular, order-flow imbalance, a central driver of short-horizon price moves, is decodable at $R^2 \approx 0.59$, far above controls and baselines.
  • The model also generalizes across metrics beyond order-flow imbalance: results hold across traded volume and volatility.

Sources (1)

  • [1]Understanding the Inner Workings of a State-Space Foundation Model for Limit Order Books
    arXiv (AI, ML, NLP, CV, robotics, multi-agent) · Oct 20, 06:01 PM
    We find that, similarly to games where sequence models build an internal representation of the board, an 8.2M-parameter Mamba-3 state-space model trained autoregressively on the tokenized message stream of eight large-cap US equities learns an internal representation of the market and its dynamics.
    Autoregressive foundation models offer state-of-the-art capabilities to simulate the market by generating the message flow of limit order books (LOBs).

Extractive summary: sentences quoted from the sources.

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