The Economics of Mutual Fund Style Drift
Facts, Controversies, and Future Research
Download Full Manuscript (PDF)Abstract
This systematic literature review synthesizes research on mutual fund style drift—the phenomenon where mutual funds deviate from their stated investment objectives over time. Following PRISMA 2020 guidelines, we conducted a dual-corpus comprehensive search of the OpenAlex database covering 1990–2025, yielding a final corpus of 71 high-quality papers with 6,580 total citations.
The literature identifies six major themes: (1) measurement methodologies, (2) determinants of style drift, (3) performance consequences, (4) investor welfare implications, (5) regulatory responses, and (6) active management dynamics. A central controversy persists: whether style drift reflects superior manager skill or agency problems. We identify twelve critical research gaps and propose a structured research agenda for future work.
Sections
1. Introduction
Motivation, research objectives, and contribution to the literature on mutual fund style drift.
2. Theoretical Framework
Agency theory, signaling theory, behavioral finance, and contract theory perspectives.
3. Methodology
PRISMA 2020 protocol, dual-corpus search strategy, and quality assessment criteria.
4. Bibliometric Analysis
Publication trends, top journals, and thematic distribution across three decades.
5. Literature Synthesis
Six thematic areas: measurement, performance, welfare, regulation, active management, determinants.
6. Discussion
Main insights, the conditional drift-performance relationship, and identified research gaps.
7. Future Research
Twelve research gaps across geographic, thematic, methodological, and temporal dimensions.
8. Conclusion
Summary of contributions, stakeholder insights, limitations, and final remarks.
Data & Documentation
Key Figures
Central Controversy: Skill vs. Agency
The persistent debate over whether style drift reflects superior manager skill (alpha-seeking behavior) or agency problems (misconduct, closet indexing) finds resolution in conditional effects. High-quality studies converge on three moderating factors:
- Intentionality: Deliberate style shifts generate +0.6% to +1.8% alpha annually; passive drift destroys -0.5% to -1.5%.
- Direction: Drift toward small-cap and value styles historically generates positive alpha.
- Manager Skill: High-Active-Share managers benefit from flexibility; low-skill managers should adhere to narrow mandates.
Methodology Highlights
Keywords: Mutual funds, style drift, style classification, return-based style analysis, holdings-based style analysis, active share, systematic literature review, PRISMA