How would you build an automated commentary engine for daily trade attribution at scale? [R]

Reddit r/MachineLearning / 4/25/2026

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Key Points

  • The post asks how to architect an automated commentary engine that produces precise, human-readable daily trade attribution from high-volume time-series trade data at scale.
  • The author highlights a key constraint: attribution math must be deterministic and accurate, so they cannot rely on LLMs to compute results due to potential hallucinations.
  • They describe a tension between flexibility and rigidity—hardcoding all attribution scenarios in an ETL pipeline makes the system too inflexible for new business cases.
  • The question invites concrete design approaches, including whether to use agentic workflows that generate and execute Python/Polars in a sandbox versus using pre-calculated cubes and structured prompts for natural-language generation.
  • They also request recommendations on specific frameworks and design patterns that have worked in financial reporting (e.g., LangChain, LlamaIndex, PandasAI).

Hey everyone,

I'm currently working through a problem in the market risk reporting space and would love to hear how you all would architect this.

The Use Case: > I have thousands of trades coming in at varying frequencies (daily, monthly). I need to build a system that automatically analyzes this time-series data and generates a precise, human-readable commentary detailing exactly what changed and why.

For example, the output needs to be a judgment like: "The portfolio variance today was +$50k, driven primarily by a shift in the Equities asset class, with the largest single contributor being Trade XYZ."

The Dilemma:

  • The Math: Absolute precision is non-negotiable. I know I can't just dump raw data into an LLM and ask it to calculate attribution, because it will hallucinate the math. I usually rely on Python and Polars for the high-performance deterministic crunching.
  • The Rigidity: If I hardcode every single attribution scenario (by asset class, by region, by specific trade) into a static ETL pipeline before feeding it to an LLM for summarization, the system becomes too rigid to handle new business scenarios automatically.

My Question:

How would you strike the balance between deterministic mathematical precision and dynamic natural language generation?

Are you using Agentic workflows (e.g., having an LLM dynamically write and execute Polars/pandas code in a sandbox)? Or are you sticking to pre-calculated cubes and heavily structured context prompts? Any specific frameworks (LangChain, LlamaIndex, PandasAI, etc.) or design patterns you've had success within financial reporting?

Appreciate any insights!

submitted by /u/Problemsolver_11
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