This study evaluates whether market-state-conditioned scenarios generated by a Conditional Wasserstein GAN with gradient penalty (cWGAN-GP) can provide portfolio-relevant covariance inputs for minimum-variance optimization. Using 55 sector-balanced S&P 500 stocks with weekly returns from 2011 to 2025, we generate 5,000 forward-looking scenarios conditioned on seven macro-financial variables and convert them into Ledoit-Wolf shrinkage covariance matrices. Historical, raw GAN-derived, and variance-rescaled GAN-derived covariance inputs are compared in long-only minimum-variance portfolios across four event-based regimes: PreCOVID2020, InflationShock2022, HighRate2023, and Recent2025. Variance-rescaled GAN covariance improves realized 13-week return and Sharpe ratio in all four selected regimes. However, GAN-based portfolios become sharply concentrated, with Effective N falling from about 29 under historical covariance to about 4. The results suggest that cWGAN-GP covariance is best interpreted as a regime-dependent allocation signal, not as a standalone calibrated risk model.
목차
Abstract 1. Introduction 2. Literature Review and Theoretical Background 2.1 Covariance Estimation and Minimum-Variance Portfolios 2.2 Generative Models for Financial Scenario Generation 2.3 Regime Detection and Regime-Aware Portfolio Construction 2.4 Research Gap: From Scenario Fit to Portfolio-Level Evaluation 3. Data and Research Design 3.1 Asset Universe and Return Data 3.2 Market-State Conditioning Variables 3.3 Event-Based Expanding-Window Design 3.4 Validation Strategy and Anti-Leakage Considerations 4. Methodology 4.1 Conditional WGAN-GP Scenario Generation 4.2 Checkpoint Selection and Scenario Reconstruction 4.3 Variance Rescaling 4.4 Covariance Matrix Construction 4.5 Portfolio Optimization and Evaluation Metrics 5. Empirical Results 5.1 Scenario Calibration: Recent2025 Diagnostic 5.2 Portfolio Allocation and Concentration 5.3 Realized OOS Performance Across Regimes 5.4 Risk-Return Metrics by Regime 5.5 Downside-Risk Diagnostics 5.6 Portfolio Dynamics within the 13-Week OOS Window 6. Discussion 6.1 Interpretation of Main Findings 6.2 The Two-Axis Framing of Regime Dependence 6.3 Why Concentration Matters 6.4 Calibration and Implementation Limits 6.5 Practical Implications and Hybrid Covariance 6.6 Statistical Interpretation under Small-Sample Conditions 6.7 Limitations and Future Work 7. Conclusion References