Dynamic Inclusion and Bounded Multi-Factor Tilts for Robust Portfolio Construction
Roberto Garrone
TL;DR
The paper tackles the fragility of mean-variance portfolios under estimation error and non-stationarity by proposing a rule-based framework that abstains from forecasting returns or covariances. It replaces optimization with dynamic eligibility and an equal-weight baseline, augmented by bounded multi-factor tilts applied deterministically on a semi-annual schedule. A key contribution is treating the investable universe as endogenous through a state-dependent constraint, enabling adaptive factor exposure without regime-detection or parameter switching, while maintaining algorithmic transparency. The approach delivers a robust core allocation suitable for long-horizon institutional use, with extensions to smaller-cap universes via liquidity-aware caps and parameter adjustments, preserving stability, interpretability, and operational feasibility. Overall, the framework provides a practical, robustness-focused alternative to parametric optimization and unconstrained factor models, facilitating core-satellite architectures that are resilient to estimation risk and regime shifts.
Abstract
This paper proposes a portfolio construction framework designed to remain robust under estimation error, non-stationarity, and realistic trading constraints. The methodology combines dynamic asset eligibility, deterministic rebalancing, and bounded multi-factor tilts applied to an equal-weight baseline. Asset eligibility is formalized as a state-dependent constraint on portfolio construction, allowing factor exposure to adjust endogenously in response to observable market conditions such as liquidity, volatility, and cross-sectional breadth. Rather than estimating expected returns or covariances, the framework relies on cross-sectional rankings and hard structural bounds to control concentration, turnover, and fragility. The resulting approach is fully algorithmic, transparent, and directly implementable. It provides a robustness-oriented alternative to parametric optimization and unconstrained multi-factor models, particularly suited for long-horizon allocations where stability and operational feasibility are primary objectives.
