A diffusion-based generative model for financial time series via geometric Brownian motion

Fuente: arXiv
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Autores principales: Kim, Gihun, Choi, Sun-Yong, Kim, Yeoneung
Formato: Preprint
Publicado: 2025
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author Kim, Gihun
Choi, Sun-Yong
Kim, Yeoneung
author_facet Kim, Gihun
Choi, Sun-Yong
Kim, Yeoneung
contents We propose a novel diffusion-based generative framework for financial time series that incorporates geometric Brownian motion (GBM), the foundation of the Black--Scholes theory, into the forward noising process. Unlike standard score-based models that treat price trajectories as generic numerical sequences, our method injects noise proportionally to asset prices at each time step, reflecting the heteroskedasticity observed in financial time series. By accurately balancing the drift and diffusion terms, we show that the resulting log-price process reduces to a variance-exploding stochastic differential equation, aligning with the formulation in score-based generative models. The reverse-time generative process is trained via denoising score matching using a Transformer-based architecture adapted from the Conditional Score-based Diffusion Imputation (CSDI) framework. Empirical evaluations on historical stock data demonstrate that our model reproduces key stylized facts heavy-tailed return distributions, volatility clustering, and the leverage effect more realistically than conventional diffusion models.
format Preprint
id arxiv_https___arxiv_org_abs_2507_19003
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A diffusion-based generative model for financial time series via geometric Brownian motion
Kim, Gihun
Choi, Sun-Yong
Kim, Yeoneung
Machine Learning
Artificial Intelligence
Numerical Analysis
60H10, 91G80, 91G60
We propose a novel diffusion-based generative framework for financial time series that incorporates geometric Brownian motion (GBM), the foundation of the Black--Scholes theory, into the forward noising process. Unlike standard score-based models that treat price trajectories as generic numerical sequences, our method injects noise proportionally to asset prices at each time step, reflecting the heteroskedasticity observed in financial time series. By accurately balancing the drift and diffusion terms, we show that the resulting log-price process reduces to a variance-exploding stochastic differential equation, aligning with the formulation in score-based generative models. The reverse-time generative process is trained via denoising score matching using a Transformer-based architecture adapted from the Conditional Score-based Diffusion Imputation (CSDI) framework. Empirical evaluations on historical stock data demonstrate that our model reproduces key stylized facts heavy-tailed return distributions, volatility clustering, and the leverage effect more realistically than conventional diffusion models.
title A diffusion-based generative model for financial time series via geometric Brownian motion
topic Machine Learning
Artificial Intelligence
Numerical Analysis
60H10, 91G80, 91G60
url https://arxiv.org/abs/2507.19003