Measuring Strategy-Decay Risk: Minimum Regime Performance and the Durability of Systematic Investing

TL;DR

This paper introduces a new quantitative framework called minimum regime performance (MRP) to measure the durability and robustness of systematic investment strategies across changing market regimes.

Contribution

It proposes MRP as a novel metric to assess how strategies perform under different regimes, highlighting the trade-off between efficiency and resilience.

Findings

Higher Sharpe ratio strategies do not always have higher MRP.

MRP captures the lowest risk-adjusted return across regimes, indicating strategy fragility.

Framework helps investors identify and manage strategy-decay risk.

Abstract

Systematic investment strategies are exposed to a subtle but pervasive vulnerability: the progressive erosion of their effectiveness as market regimes change. Traditional risk measures, designed to capture volatility or drawdowns, overlook this form of structural fragility. This article introduces a quantitative framework for assessing the durability of systematic strategies through minimum regime performance (MRP), defined as the lowest realized risk-adjusted return across distinct historical regimes. MRP serves as a lower bound on a strategy's robustness, capturing how performance deteriorates when underlying relationships weaken or competitive pressures compress alpha. Applied to a broad universe of established factor strategies, the measure reveals a consistent trade-off between efficiency and resilience -- strategies with higher long-term Sharpe ratios do not always exhibit higher MRPs. By translating the persistence of investment efficacy into a measurable quantity, the framework provides investors with a practical diagnostic for identifying and managing strategy-decay risk, a novel dimension of portfolio fragility that complements traditional measures of market and liquidity risk.