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Overparametrized models with posterior drift

Guillaume Coqueret, Martial Laguerre

arXiv 30 Jun 2025 · Finance — Statistical Finance

arXiv:2506.23619 · PDF · DOI · OpenAlex · Extracted main text

Abstract

This paper investigates the impact of posterior drift on out-of-sample forecasting accuracy in overparametrized machine learning models. We document the loss in performance when the loadings of the data generating process change between the training and testing samples. This matters crucially in settings in which regime changes are likely to occur, for instance, in financial markets. Applied to equity premium forecasting, our results underline the sensitivity of a market timing strategy to sub-periods and to the bandwidth parameters that control the complexity of the model. For the average investor, we find that focusing on holding periods of 15 years can generate very heterogeneous returns, especially for small bandwidths. Large bandwidths yield much more consistent outcomes, but are far less appealing from a risk-adjusted return standpoint. All in all, our findings tend to recommend cautiousness when resorting to large linear models for stock market predictions.

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43
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Most heavily cited references

The works this paper leans on most, across its whole bibliography — not restricted to papers in our corpus. Ranked by composite intensity, which combines how often a work is mentioned, how many sections mention it, and how much of that falls in the main text rather than the appendix.

ReferenceIntensityMentionsSectionsMain text
1Kelly, B. T., S. Malamud, and K. Zhou (2024) The virtue of complexity in return prediction1.000244100%
2Hastie, T., A. Montanari, S. Rosset, and R. J. Tibshirani (2022) Surprises in high-dimensional ridgeless least squares interpolation0.89911373%
3Bartlett, P. L., P. M. Long, G. Lugosi, and A. Tsigler (2020) Benign overfitting in linear regression0.64422100%
4Shen, Z. and D. Xiu (2025) Can machines learn weak signals?0.64422100%
5Hastie, T., A. Montanari, S. Rosset, and R. J. Tibshirani (2020) Surprises in high-dimensional ridgeless least squares interpolation0.5115220%
6Fallahgoul, H (2025) High-dimensional learning in finance0.51121100%
7Goyal, A., I. Welch, and A. Zafirov (2024) A comprehensive 2022 look at the empirical performance of equity premium prediction0.51121100%
8Londschien, M., P. Bühlmann, and S. Kovács (2023) Random forests for change point detection0.51121100%
9Enikeeva, F. and Z. Harchaoui (2019) High-dimensional change-point detection under sparse alternatives0.40511100%
10Frick, K., A. Munk, and H. Sieling (2014, 05) (2014) Multiscale Change Point Inference0.40511100%

Showing the top 10 of 43 scored citations.