What are ESG Ratings?

What are ESG Ratings?

ESG ratings are assessments produced by specialized rating agencies—MSCI, Sustainalytics (Morningstar), S&P Global, ISS, and others—that evaluate a company's exposure to environmental, social, and governance risks and the quality of its management response. Unlike credit ratings, which converge around a common methodology, ESG ratings vary significantly across providers in methodology, scope, data sources, and output. MSCI uses a letter scale (AAA to CCC), Sustainalytics uses a numerical risk score, and S&P Global produces 0–100 scores. These ratings influence index inclusion, investment screening, capital allocation, and increasingly, lending decisions.

Why It Matters

ESG ratings directly affect capital flows. A rating downgrade can trigger automatic exclusion from ESG funds and indices. When a company drops from an "A" to "BBB" rating, it can lose access to a meaningful portion of its investor base, increasing capital costs and reducing share price support from passive ESG flows.

The divergence problem is well-documented and consequential. A landmark MIT study found that the correlation between major ESG rating providers is only 0.54, compared to 0.99 for credit ratings. In 2018, for example, MSCI ranked Tesla at the top of the auto industry on ESG while FTSE Russell rated it the worst carmaker globally, as the Wall Street Journal reported. This divergence creates confusion for companies trying to manage their ratings, for investors trying to integrate ESG factors, and for regulators trying to prevent greenwashing.

Regulatory intervention is reshaping the ratings landscape. The EU adopted a regulation on ESG rating providers in 2024, requiring transparency about methodologies, conflict of interest management, and ESMA supervision; it has applied since July 2, 2026. India's SEBI has required ESG rating providers to register with it since July 2023. These regulations aim to improve reliability and reduce the information asymmetry that currently characterizes the market. Companies should expect more transparency about how ratings are built, though the EU rules do not standardize rating methodologies.

Despite their limitations, ESG ratings function as a de facto accountability mechanism. Some companies tie executive compensation to ESG rating improvements. Lenders incorporate ESG scores into credit risk models. M&A due diligence routinely includes ESG rating analysis. Ignoring ratings—or dismissing their methodology—doesn't make the capital market consequences disappear.

How It Works / Key Components

ESG rating methodologies generally follow three steps: identify material ESG issues for the company's industry, assess exposure to those issues, and evaluate management quality and track record. MSCI's methodology weights environmental, social, and governance pillars differently by industry—mining companies face heavy environmental weighting, while financial services companies see governance weighted more heavily.

Data inputs come from company disclosures (sustainability reports, annual filings, CDP responses), regulatory databases (EPA emissions data, OSHA violations), news and controversy monitoring, and direct company engagement (surveys and interviews). The balance between disclosed data and estimated data varies, and estimates fill gaps for companies that don't disclose comprehensively. This estimation introduces noise and contributes to rating divergence.

Rating agencies differ in what they're actually measuring. MSCI focuses on financially material ESG risks relative to industry peers—a "best in class" approach where an oil company can earn an "AA" by managing its ESG risks better than peers, regardless of absolute environmental impact. Sustainalytics measures unmanaged ESG risk exposure in absolute terms. S&P Global assesses both ESG performance and momentum. This methodological divergence means companies must understand what each rating actually represents rather than treating all ratings as interchangeable.

Companies can actively manage their ratings through three levers: improving actual ESG performance (the substantive lever), improving disclosure quality and completeness (the transparency lever), and engaging directly with rating agencies to correct data errors and provide context (the communication lever).

Council Fire's Approach

Council Fire helps clients navigate the ESG ratings landscape by analyzing current ratings across providers, identifying the specific data gaps and performance issues driving scores, and developing targeted improvement strategies. We focus on substantive improvements that simultaneously enhance ratings and reduce actual risk, rather than superficial disclosure optimization—ensuring clients build durable ESG credibility with investors and rating agencies.

Frequently Asked Questions

Why do different ESG rating agencies give my company different scores?

Three sources of divergence drive rating discrepancies: scope (which ESG issues each agency considers), measurement (what metrics and data sources they use), and weighting (how they combine scores across issues). A company might score well on environmental metrics with one agency that uses self-reported data but poorly with another that relies on third-party monitoring data. Industry classification differences also matter—if agencies categorize your company in different peer groups, the benchmarks change entirely. Understanding each agency's specific methodology is essential for interpreting and managing your ratings.

How much do ESG ratings actually affect cost of capital?

Empirical evidence is growing. MSCI research covering August 2015 to May 2024 found that companies with higher MSCI ESG Ratings had lower costs of capital in both equity and debt markets, with a statistically significant gap between the top and bottom quintiles. On the debt side, some sustainability-linked loans tie pricing directly to ratings: the first such loan, Philips's €1 billion credit facility in 2017, linked its interest rate to the company's Sustainalytics ESG rating. The effect of any single rating change depends on who uses that rating and how financially material ESG factors are in the sector.

Should my company focus on improving one specific ESG rating?

Focus on the ratings that matter most to your investor base and capital structure. If your top 10 institutional shareholders use MSCI data, prioritize understanding MSCI's methodology. If you're issuing sustainability-linked bonds referencing Sustainalytics, focus there. However, improving underlying ESG performance and disclosure quality tends to lift all ratings simultaneously. The most efficient approach is identifying cross-cutting gaps—such as missing climate disclosure or absent board diversity policies—that negatively affect ratings across multiple providers, then addressing those first.