Investment Strategies for ESG Funds: A Comparative Review of Performance, Risk, and Market Practice

Abstract

Environmental, Social, and Governance (ESG) investing has grown from a small, values-based idea into a mainstream investment practice that now guides trillions of dollars in capital. Despite this growth, three basic questions remain open: does ESG investing improve or reduce risk-adjusted returns; can investors trust ESG ratings and fund labels; and which ESG strategy negative screening, positive/best-in-class screening, ESG integration, thematic investing, impact investing, or active ownership best fits a given investor's goal? This paper reviews and compares ESG fund strategies using more than thirty peer-reviewed studies, industry reports, and regulatory sources published between 2003 and 2026. It (i) builds a simple comparison framework covering the six main ESG strategies; (ii) summarizes evidence on performance, rating disagreement, and greenwashing; (iii) presents data on the growth and composition of the global sustainable investment market; and (iv) explains how ESG data can be processed using modern information-system, portfolio-optimization, and machine-learning methods, and what this means for investors, fund managers, and policymakers. The review finds that financial-performance evidence is genuinely mixed rather than conclusively positive or negative, that rating disagreement and greenwashing are structural problems rather than occasional errors, and that the right strategy depends on a clear statement of investor goals, financial, ethical, or both, rather than on marketing labels alone.