How Much Does the Hint Matter? Scope Conditions for Hindsight Self-Distillation in Financial Reasoning
Organizations: University of California, Berkeley Berkeley, California, USA · CTGT San Francisco, California, USA
Abstract
Financial institutions operating under data-residency constraints are restricted to open-weight models small enough to locally host, which trail frontier systems on multi-step quantitative reasoning. On-policy distillation narrows such gaps by supervising a student on its own rollouts, but traditional OPD requires a strong external teacher, and on-policy self-distillation (OPSD) conditions on a full reference solution. We ask how much of that signal is necessary. We present Fin-SD, a localized hindsight self-distillation recipe for multi-step reasoning. Given a problem the student fails, the student itself identifies the first incorrect reasoning step and writes a short critique of that step. We truncate the student's trajectory immediately before the error (aiming to obtain a correct prefix), condition a frozen copy of the student on the same prefix plus the hint, and distill that hint-conditioned teacher into the student over a short rollout under reverse KL. No external model contributes a gradient. We apply Fin-SD to GPT-OSS-20B on a custom multi-step financial reasoning benchmark that requires deriving formula inputs from realistic scenarios via accounting conventions. We find: (i) replacing the critique with a generic-feedback control matches Fin-SD's entire 3.03 pp accuracy gain over the base model on the FinanceReasoning Hard subset, suggesting the gain comes from where supervision is applied, not hint content; (ii) the model writing the hint does not need to be stronger than the model receiving it: hints from same-family GPT-OSS-120B, at roughly 6x the parameters, yield no materially greater benefits than self-written hints; and (iii) Fin-SD matches on-policy self-distillation from full reference solutions on accuracy while generating 9.5% fewer tokens. With Fin-SD, general reasoning on MMLU-Pro and a fourteen-metric compliance audit on FinTrust show no material regression.
Figures & tables
| Setting | Value |
|---|---|
| Model and optimization | |
| Student model | GPT-OSS-20B ( OpenAI, 2025 ) |
| Student model effort | Medium |
| LoRA attention | |
| LoRA | |
| LoRA expert | |
| Configuration | Accuracy (%) | 95% CI | Completion rate (%) | 95% CI | Tokens (k) | 95% CI | |
|---|---|---|---|---|---|---|---|
| Fin-SD | 5 | ||||||
| OPSD (full solution) | 5 | ||||||
| Base | 5 | ||||||
| SFT | 3 |
| Base | Fin-SD | ||
|---|---|---|---|
| Overall accuracy (%) | pp | ||
| Execution rate (%) | pp | ||
| Mean tokens | 1,742 | 1,692 |
| Dimension / metric | Base | Fin-SD | Change |
|---|---|---|---|
| Trustfulness — hallucination (%) | flat | ||
| Trustfulness — refuse-to-answer (%) | |||
| Trustfulness — correctness (%) | |||
| Trustfulness — informativeness (1–5) | |||
| Robustness — answerable (1–6) | |||
| Robustness — unanswerable (1–6) |
| Acc. (%) | Compl. (%) | Tok. (k) | ||
|---|---|---|---|---|
| Fin-SD ( self , RKL) | ||||
| self | FKL | |||
| 120b | FKL | |||
| 120b | RKL | |||
| Rollout length ( ) | ||||
Self-Distillation
Self-distillation trains a model from its own predictions, representations, or experience to improve capability, efficiency, and robustness.
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