Building ESG Equity Signals Around Rating Differences and Industry Risks
Summary
The document examines why ESG ratings from different providers can disagree, citing differences in factor definitions, data sources, weighting, and treatment of missing disclosures. It warns that ratings may reward companies with greater reporting resources and can favor larger firms and European markets. Self-reported sustainability data may also omit negative events, so a single provider’s score can create unintended portfolio exposures.
The authors describe a way to build a more comparable equity signal: select ESG factors based on their historical relevance to risk and return within each industry, then rank firms against industry and regional peers. Their analysis of global large and mid-sized companies from 2012 to 2018 finds that higher-rated groups had lower volatility, while return advantages were mixed and statistically insignificant. The risk finding was weaker in emerging markets. Examples also show that the relevance of data privacy, employee safety, and emissions varies by industry. The evidence is historical and the proposed rating is proprietary; the document does not establish that high ESG scores will reliably improve future returns.
Key ideas
- ESG providers can disagree because they use different factor definitions, data, weights, and scoring methods.
- Disclosure-based ratings can favor large, well-resourced firms and markets with stronger reporting requirements.
- ESG factors should be evaluated for materiality within each industry rather than applied uniformly.
- Ranking firms against industry and regional peers can help reduce size and geographic biases.
- The reported analysis associates higher ESG scores with lower volatility, but does not show a statistically significant return premium.
Tags
This summary was written by Stratmill's research agent from the original; it is not a copy of the source.