A Theoretical Framework for LLM Fine-tuning Using Early Stopping for Non-random Initialization

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Autori principali: Sun, Zexuan, Raskutti, Garvesh
Natura: Preprint
Pubblicazione: 2026
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author Sun, Zexuan
Raskutti, Garvesh
author_facet Sun, Zexuan
Raskutti, Garvesh
contents In the era of large language models (LLMs), fine-tuning pretrained models has become ubiquitous. Yet the theoretical underpinning remains an open question. A central question is why only a few epochs of fine-tuning are typically sufficient to achieve strong performance on many different tasks. In this work, we approach this question by developing a statistical framework, combining rigorous early stopping theory with the attention-based Neural Tangent Kernel (NTK) for LLMs, offering new theoretical insights on fine-tuning practices. Specifically, we formally extend classical NTK theory [Jacot et al., 2018] to non-random (i.e., pretrained) initializations and provide a convergence guarantee for attention-based fine-tuning. One key insight provided by the theory is that the convergence rate with respect to sample size is closely linked to the eigenvalue decay rate of the empirical kernel matrix induced by the NTK. We also demonstrate how the framework can be used to explain task vectors for multiple tasks in LLMs. Finally, experiments with modern language models on real-world datasets provide empirical evidence supporting our theoretical insights.
format Preprint
id arxiv_https___arxiv_org_abs_2602_13942
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A Theoretical Framework for LLM Fine-tuning Using Early Stopping for Non-random Initialization
Sun, Zexuan
Raskutti, Garvesh
Machine Learning
In the era of large language models (LLMs), fine-tuning pretrained models has become ubiquitous. Yet the theoretical underpinning remains an open question. A central question is why only a few epochs of fine-tuning are typically sufficient to achieve strong performance on many different tasks. In this work, we approach this question by developing a statistical framework, combining rigorous early stopping theory with the attention-based Neural Tangent Kernel (NTK) for LLMs, offering new theoretical insights on fine-tuning practices. Specifically, we formally extend classical NTK theory [Jacot et al., 2018] to non-random (i.e., pretrained) initializations and provide a convergence guarantee for attention-based fine-tuning. One key insight provided by the theory is that the convergence rate with respect to sample size is closely linked to the eigenvalue decay rate of the empirical kernel matrix induced by the NTK. We also demonstrate how the framework can be used to explain task vectors for multiple tasks in LLMs. Finally, experiments with modern language models on real-world datasets provide empirical evidence supporting our theoretical insights.
title A Theoretical Framework for LLM Fine-tuning Using Early Stopping for Non-random Initialization
topic Machine Learning
url https://arxiv.org/abs/2602.13942