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The Nonstationarity-Complexity Tradeoff in Return Prediction

Bibliographic record. Follow the original-source link for the publication.

Field Value
Primary domain Financial Model Validation
Other domains —
Methods Financial Ml, Research Methods
Facets —
Authors Agostino Capponi, Chengpiao Huang, J. Antonio Sidaoui, Kaizheng Wang, Jiacheng Zou
Published 2025-12-29
Source SSRN Financial Economics Network
Identifiers doi:10.2139/ssrn.5980654, ssrn:5980654
URL Open original source

Editorial synthesis

Why it matters

The paper links model complexity to how much training and validation history remains useful after distribution shifts. It motivates financial model-selection research, not a validated solution for option, quantile or ranking targets. (full_text:S33, full_text:S37, full_text:S98, full_text:S160, description:S6)

Main author claims

  • The authors report: Under independent-batch and boundedness assumptions, the authors bound squared-error excess risk using approximation, estimation and distribution-shift terms. The tradeoff does not establish a universal preference for simpler models or shorter windows. (full_text:S33, full_text:S98, full_text:S99, full_text:S160, full_text:S220)
  • The authors report: ATOMS compares candidates using pair-specific validation lookbacks and a randomized tournament. Candidates span model classes, hyperparameters and training windows. Expected linear comparison count does not include fitting the candidate grid. (full_text:S37, full_text:S267, full_text:S269, full_text:S270, full_text:S286, full_text:S321)
  • The authors report: Across 17 U.S. industries, Table 3 reports zero-forecast OOS R² of 0.049 versus 0.043 for the strongest fixed-window benchmark, January 1990–November 2016. That is +0.006, about 14% relatively, not +14 percentage points; not replicated here. (full_text:S40, full_text:S41, full_text:S387, full_text:S388)

Data, method, or discussion scope

The study combines 17 industries and 129 predictors, September 1987–November 2016, using daily models and monthly evaluation. Twenty past-month splits are not independent market histories. Q4 follows SSRN posting on December 29, 2025; the read 109-page revision is dated August 13, 2026. (full_text:S324, full_text:S335, full_text:S376, full_text:S377, description:S7, description:S8)

Main limitations

Theory relies on independence/boundedness; practical M′ uses a historical percentile. Costs use 4e-4/252 per turnover, not 4 bp per trade. Sharpe averages within-month daily-return ratios. Feature lags/vintages were not code-audited: PIT safety is unverified, not disproved. Preprint; no replication or independent proof verification. (full_text:S98, full_text:S99, full_text:S160, full_text:S466, full_text:S468, full_text:S471, full_text:S724, full_text:S727, full_text:S734, full_text:S745, full_text:S916)

Relationships