Major ESG Ratings Agencies

The ESG ratings industry is dominated by a relatively small number of specialized agencies that assess thousands of companies worldwide using proprietary methodologies. These agencies serve as critical information intermediaries, translating complex sustainability data into standardized ratings that influence trillions of dollars in investment decisions. While dozens of ESG rating and data providers operate globally, a core group of approximately ten major agencies account for the vast majority of market influence and coverage.¹ Understanding the distinct approaches, strengths, and limitations of each major provider is essential for investors, companies, and other stakeholders using ESG ratings.

The agencies profiled here represent the most widely used and influential ESG rating providers as of 2025, selected based on market share, coverage breadth, institutional adoption, and impact on capital flows. Each agency brings unique capabilities, methodological approaches, and market positioning, reflecting the diversity of user needs and applications for ESG ratings.

MSCI ESG Ratings

MSCI Inc., a leading provider of investment decision support tools, offers ESG ratings that have become among the most widely referenced in global financial markets. MSCI ESG Research covers over 17,000 issuers and 999,000 securities, providing comprehensive global coverage including emerging markets.²

Methodology: MSCI employs an industry-adjusted, relative rating approach that evaluates companies on their exposure to financially material ESG risks and their management of those risks compared to industry peers. The methodology assigns companies to one of 38 ESG Rating Industries, recognizing that material ESG issues vary significantly across sectors. Within each industry, companies receive scores on dozens of Key Issues identified through MSCI's ESG Industry Materiality Map, which is updated annually to reflect evolving risk landscapes. Individual Key Issue scores are aggregated using weighted averages to produce overall ESG scores on a 0-10 scale, which are then translated into letter ratings from AAA (leader) to CCC (laggard) based on percentile ranks within each industry.³

Rating Scale: MSCI's seven-level rating scale categorizes companies as Leaders (AAA, AA), Average (A, BBB, BB), or Laggards (B, CCC). Approximately 15% of companies receive AAA or AA ratings, 70% receive A through BB ratings, and 15% receive B or CCC ratings, creating a roughly normal distribution within each industry. The industry-relative approach means that a company in a high-impact sector like oil and gas can achieve a strong rating if it manages ESG risks better than industry peers, even if its absolute environmental footprint is large.

Controversies: MSCI maintains a separate ESG Controversies assessment that monitors companies' involvement in incidents related to ESG issues. Controversies receive scores and color-coded flags based on severity, company role, and status (ongoing or resolved). Importantly, controversies scores supplement but do not directly determine ESG ratings, allowing MSCI to maintain rating stability while flagging emerging issues. This separation means a company can maintain a strong ESG rating despite involvement in significant controversies if its overall risk management systems remain robust.

Strengths and Applications: MSCI's industry-adjusted approach enables meaningful comparison within sectors, making it particularly useful for sector-focused investors and portfolio managers constructing industry-neutral ESG portfolios. The extensive coverage and integration with MSCI's broader index and analytics ecosystem facilitate adoption by institutional investors. MSCI ESG ratings feed into widely-followed indices including the MSCI ESG Leaders Indexes and MSCI SRI Indexes, directly influencing passive investment flows.

Sustainalytics (Morningstar)

Sustainalytics, acquired by Morningstar in 2020, provides ESG Risk Ratings for over 15,000 companies globally using a distinctive absolute risk approach that differs fundamentally from MSCI's relative methodology.⁴

Methodology: Sustainalytics' ESG Risk Ratings assess the degree to which a company's economic value is at risk from ESG factors, focusing specifically on unmanaged ESG risks that remain after accounting for company management efforts. The methodology evaluates Material ESG Issues (MEIs) relevant to each company based on its sub-industry and business model, measuring both the magnitude of risk exposure and the quality of management programs addressing those risks. The difference between total exposure and managed risk yields an Unmanaged Risk score, which represents the ESG risk that could materially impact enterprise value.

Rating Scale: Companies receive numerical Unmanaged Risk scores that are categorized into five risk levels: Negligible (0-10), Low (10-20), Medium (20-30), High (30-40), and Severe (40+). This absolute approach enables cross-industry comparison, as scores reflect absolute levels of unmanaged risk rather than relative performance within sectors. A company in a high-impact industry with significant unmanaged risks will receive a High or Severe rating regardless of how it compares to industry peers, contrasting with MSCI's relative approach.

Integration with Morningstar: Since acquisition by Morningstar, Sustainalytics' ESG Risk Ratings have been integrated into the Morningstar investment research platform, providing seamless access for retail and institutional investors already using Morningstar's tools. This integration has driven significant adoption growth, particularly among retail-focused asset managers and financial advisors. Morningstar's Sustainability Rating (globe rating) for mutual funds and ETFs incorporates Sustainalytics' company-level ESG Risk Ratings, creating direct connections between company sustainability performance and fund-level assessments.

Strengths and Applications: The absolute risk approach appeals to investors seeking to compare ESG risks across industries and construct portfolios with specific risk thresholds. The focus on unmanaged risk provides insight into residual exposures that could impact valuations, complementing traditional financial risk assessments. Sustainalytics' strong position in Second Party Opinions for green bonds and sustainability-linked bonds extends its influence beyond equity ratings into fixed income markets.

Bloomberg ESG Data

Bloomberg L.P., the financial data and media giant, leverages its Terminal infrastructure to provide real-time ESG data and analytics to over 325,000 subscribers worldwide.⁵

Methodology: Bloomberg's ESG data service collects information on environmental, social, and governance factors from more than 15,500 companies in over 100 countries, combining company-reported data with alternative data sources including satellite imagery, social media sentiment analysis, and real-time news monitoring. Rather than producing a single proprietary ESG rating, Bloomberg provides comprehensive data across hundreds of ESG metrics, enabling users to construct custom scores and screens tailored to their specific needs. Bloomberg does offer ESG Disclosure Scores that measure the extent and quality of companies' ESG reporting, providing a transparency metric distinct from performance assessment.

Platform Integration: Bloomberg's distinctive strength lies in its seamless integration of ESG data with traditional financial analytics within the familiar Terminal environment. Users can analyze ESG metrics alongside financial data, create custom screens combining ESG and financial criteria, and monitor ESG developments in real-time. This integration eliminates the need for investors to juggle multiple platforms and enables sophisticated analysis combining sustainability and financial factors.

Alternative Data: Bloomberg's incorporation of alternative data sources provides unique insights unavailable from survey-based rating providers. Satellite imagery can track deforestation, industrial emissions, and facility operations; social media sentiment analysis can identify emerging reputational risks; and real-time news monitoring enables rapid identification of ESG controversies. These alternative data sources complement conventional disclosure-based data, providing more comprehensive and timely information.

Strengths and Applications: Bloomberg's real-time capabilities and platform integration make it particularly valuable for active investors requiring current information and flexible analysis tools. The emphasis on data provision rather than proprietary ratings appeals to sophisticated users who prefer to construct their own assessments. Bloomberg's extensive financial data coverage enables analysis of relationships between ESG factors and financial performance.

S&P Global ESG Scores

S&P Global, one of the "Big Three" credit rating agencies alongside Moody's and Fitch, provides ESG assessments that integrate sustainability factors with credit risk analysis.⁶

Methodology: S&P Global's ESG Scores assess companies' preparedness to manage future ESG risks and opportunities, using a methodology that considers both current performance and forward-looking capacity. The assessment covers corporate, sovereign, and municipal sectors, with sector-specific frameworks recognizing material differences in ESG risks across entity types. S&P's approach emphasizes the connection between ESG factors and creditworthiness, drawing on decades of credit analysis expertise to identify sustainability issues with potential financial materiality.

Credit Integration: S&P Global's distinctive strength lies in its integration of ESG assessment with credit rating analysis. While ESG Scores are produced separately from credit ratings, the same analytical teams often contribute to both, creating natural connections between sustainability and credit perspectives. This integration enables investors to understand how ESG factors influence credit risk, supporting fixed income investors who need both ESG and credit insights. S&P has increasingly incorporated ESG factors explicitly into credit rating rationales, enhancing transparency about sustainability's role in creditworthiness assessments.

Coverage: S&P Global provides comprehensive coverage across asset classes, including corporate entities, sovereigns, and municipal issuers. This breadth enables consistent ESG assessment across diversified portfolios. Real-time monitoring capabilities allow rapid response to emerging ESG issues that could affect credit quality, supporting dynamic risk management.

Strengths and Applications: The credit-integrated approach appeals particularly to fixed income investors, credit analysts, and risk managers focused on debt securities. S&P's established relationships with corporate issuers and regulators, built through decades of credit rating work, facilitate ESG data collection and engagement. The combination of ESG and credit perspectives provides holistic risk assessment.

FTSE Russell ESG Ratings

FTSE Russell, a subsidiary of the London Stock Exchange Group (LSEG), provides ESG ratings that directly influence hundreds of billions of dollars in passive investment flows through widely-followed indices.⁷

Methodology: FTSE Russell's ESG Ratings assess companies' ESG practices, policies, and performance across 14 themes organized into three pillars (Environmental, Social, Governance). The methodology evaluates over 300 individual indicators, with weights determined by sector-specific materiality. Companies receive overall ESG ratings on a 0-5 scale, with separate pillar and theme scores enabling granular analysis. The ratings feed directly into FTSE Russell's ESG index construction, including the FTSE4Good Index Series and FTSE ESG Ratings-based indices.

Green Revenues Classification: A distinctive feature of FTSE Russell's offering is its Green Revenues data model, which provides detailed analysis of revenue streams from environmental solutions. The classification system identifies and measures revenues from products and services contributing to environmental objectives including renewable energy, energy efficiency, water infrastructure, waste management, and pollution control. This granular revenue analysis enables investors to measure portfolio exposure to the transition economy and construct thematic strategies focused on environmental solutions.

Index Influence: FTSE Russell's ESG ratings directly determine inclusion in ESG indices that serve as benchmarks for hundreds of billions in passive investments. Companies meeting FTSE4Good inclusion criteria benefit from index-driven investment flows, while exclusion can trigger divestment. This direct connection between ratings and capital flows gives FTSE Russell significant influence over corporate behavior, as companies seek to achieve and maintain index inclusion.

Strengths and Applications: The tight integration between ratings and indices makes FTSE Russell particularly relevant for passive investors and index-focused strategies. The Green Revenues classification system provides unique insights for thematic investing and transition finance. FTSE Russell's position within LSEG creates synergies with exchange data and other LSEG services.

ISS (Institutional Shareholder Services)

ISS, founded in 1985, combines traditional proxy advisory services with comprehensive ESG research, creating an integrated view of corporate governance and sustainability.⁸

Methodology: ISS ESG (formerly ISS-oekom) provides ESG Corporate Ratings that assess companies' ESG performance on a 12-grade scale from A+ (excellent) to D- (poor). The methodology evaluates over 100 sector-specific criteria organized into environmental and social categories, with governance assessment integrated through ISS's core proxy research. ISS's decades of expertise in corporate governance provide deep insights into board effectiveness, executive compensation, shareholder rights, and other governance factors that many ESG rating providers treat more superficially.

Proxy Voting Integration: ISS's distinctive strength lies in its integration of ESG research with proxy voting recommendations. As the leading proxy advisory firm, ISS provides voting recommendations to institutional investors holding trillions in assets, directly influencing shareholder votes on director elections, executive compensation, shareholder proposals, and other matters. ISS increasingly incorporates ESG factors into voting recommendations, connecting sustainability performance to governance outcomes. For example, ISS may recommend voting against directors at companies with poor climate risk management or significant ESG controversies.

Governance Expertise: ISS's deep expertise in corporate governance, built over decades of proxy advisory work, provides authoritative analysis of board structures, compensation practices, shareholder rights, and governance mechanisms. This governance focus complements environmental and social assessment, recognizing that effective governance enables proper management of all ESG risks. ISS's governance research informs both ESG ratings and proxy voting recommendations, creating consistent application of governance principles.

Strengths and Applications: The integration of ESG research with proxy voting makes ISS particularly valuable for institutional investors engaged in active ownership and stewardship. ISS's influence over proxy voting outcomes gives it significant leverage to drive corporate behavior change. The governance expertise appeals to investors who view governance as foundational to ESG performance.

EcoVadis

EcoVadis, founded in 2007 and headquartered in Paris, specializes in supply chain sustainability ratings, creating what it describes as the world's most comprehensive network of supplier ESG assessments.⁹

Methodology: EcoVadis assesses companies across four themes: Environment, Labor & Human Rights, Ethics, and Sustainable Procurement. The methodology extends beyond questionnaires to include document analysis, on-site audits when warranted, and stakeholder feedback. Companies receive scores on a 0-100 scale, with recognition levels (Bronze, Silver, Gold, Platinum) awarded to top performers. EcoVadis emphasizes continuous improvement, providing detailed scorecards and corrective action plans that position the service as a development partner rather than merely a rating provider.

Collaborative Marketplace: EcoVadis operates a collaborative marketplace model where buyers can share supplier assessments, reducing duplication and cost. A single EcoVadis assessment can be shared with multiple customers, eliminating the need for suppliers to respond to numerous separate sustainability questionnaires. This network effect has driven rapid adoption, with over 100,000 companies assessed on the EcoVadis platform as of 2025. The marketplace model creates incentives for suppliers to achieve strong ratings to attract and retain customers.

Supply Chain Focus: EcoVadis's supply chain specialization addresses a critical gap in ESG assessment, as most rating providers focus on large publicly-traded companies while supply chain risks often concentrate in smaller, private suppliers. EcoVadis enables companies to assess ESG risks throughout their supply chains, supporting due diligence requirements under regulations including the EU Corporate Sustainability Due Diligence Directive and various modern slavery laws.

Strengths and Applications: The supply chain focus makes EcoVadis essential for companies managing supplier sustainability and conducting ESG due diligence. The improvement-oriented approach with detailed action plans supports supplier development rather than merely identifying risks. The collaborative marketplace reduces assessment burden on suppliers while providing buyers with standardized, comparable data.

CDP (Carbon Disclosure Project)

CDP, founded in 2000 and headquartered in London, operates as the primary global environmental disclosure platform, with companies voluntarily reporting climate, water, and forest-related data through CDP's questionnaires.¹⁰

Methodology: CDP collects environmental data through annual questionnaires covering climate change, water security, and forests. Companies respond to detailed questions about environmental risks, impacts, strategies, and performance, with responses scored by CDP using letter grades from A (leadership) to D- (disclosure). CDP's A-List recognition has become a status symbol, with companies investing substantially in environmental initiatives to achieve top-tier ratings. The methodology emphasizes disclosure quality and environmental action, rewarding companies that demonstrate comprehensive measurement, management, and mitigation of environmental impacts.

Collaborative Approach: CDP collaborates closely with regulators and policymakers, helping shape emerging disclosure requirements while collecting data that companies need to meet those requirements. CDP's questionnaires have influenced regulatory disclosure frameworks including the Task Force on Climate-related Financial Disclosures (TCFD) and the ISSB's climate standard (IFRS S2). This collaborative approach positions CDP as both a data collector and a standard-setter, with its questionnaires serving as de facto disclosure frameworks even in the absence of mandatory requirements.

Environmental Focus: CDP's exclusive focus on environmental issues enables depth of coverage that generalist ESG rating providers cannot match. The climate change questionnaire covers greenhouse gas emissions, climate risks and opportunities, governance, strategy, and targets in extensive detail. Water and forests questionnaires provide similarly comprehensive coverage of these critical environmental issues. This specialization appeals to investors and stakeholders prioritizing environmental factors.

Strengths and Applications: CDP's position as the primary environmental disclosure platform makes it essential for investors seeking comprehensive climate and environmental data. The A-List recognition provides a clear benchmark for corporate environmental leadership. CDP's data feeds into numerous ESG ratings and indices, amplifying its influence. The collaborative approach with regulators ensures alignment between voluntary disclosure and emerging mandatory requirements.

Moody's ESG Solutions

Moody's Corporation, one of the "Big Three" credit rating agencies, provides ESG assessments that integrate sustainability factors with credit risk analysis, similar to S&P Global's approach.¹¹

Methodology: Moody's ESG Solutions offers ESG Scores that assess companies' exposure to ESG risks and their management of those risks, using a methodology that emphasizes credit-relevant ESG factors. The assessment draws on Moody's decades of credit analysis expertise to identify sustainability issues with potential financial materiality. Moody's has developed cross-sector and sector-specific methodologies for integrating ESG factors into credit ratings, providing transparency about how sustainability considerations influence creditworthiness assessments.

Credit Integration: Moody's distinctive strength lies in its deep integration of ESG factors into credit rating analysis. Moody's credit ratings increasingly incorporate explicit consideration of ESG factors, with rating rationales discussing how environmental, social, and governance issues influence credit risk. This integration enables fixed income investors to understand sustainability's role in creditworthiness, supporting investment decisions and risk management. Moody's has published extensive research on connections between ESG factors and credit outcomes, building an evidence base for ESG integration.

Strengths and Applications: The credit-integrated approach appeals particularly to fixed income investors, credit analysts, and risk managers. Moody's established relationships with corporate issuers and regulators, built through decades of credit rating work, facilitate ESG data collection and engagement. The combination of ESG and credit perspectives provides holistic risk assessment for debt investors.

Fitch ESG Ratings

Fitch Ratings, the third member of the "Big Three" credit rating agencies, provides ESG Relevance Scores that indicate which ESG factors are material and relevant to individual credit ratings.¹²

Methodology: Fitch's ESG Relevance Scores are assigned to 15 bespoke ESG issues on a '1' to '5' scale that captures how an issue may affect an individual entity's credit rating. Scores of '4' (relevant) or '5' (highly relevant) indicate that ESG factors have material influence on the credit rating, while scores of '1' to '3' indicate minimal or no impact. This approach provides transparency about ESG's role in credit decisions, enabling investors to understand which sustainability factors matter for creditworthiness.

Credit Integration: Fitch's ESG Relevance Scores are produced by the same credit analysts who assign credit ratings, ensuring tight integration between ESG assessment and credit analysis. The scores appear directly in credit rating reports, making ESG considerations explicit and transparent. This integrated approach contrasts with separate ESG ratings that may not clearly connect to credit outcomes.

Strengths and Applications: The ESG Relevance Score approach provides clear, transparent connections between specific ESG factors and credit ratings. The integration with credit analysis ensures that ESG assessment focuses on financially material issues. Fitch's established credit rating relationships facilitate ESG data collection and engagement.

LSEG (London Stock Exchange Group) / Refinitiv

LSEG, through its Refinitiv data business, provides ESG scores for over 11,000 companies globally using a percentile rank methodology.¹³

Methodology: LSEG ESG scores assess companies' ESG performance, commitment, and effectiveness using over 500 company-level ESG metrics derived from publicly available data. Companies receive overall ESG scores and separate pillar scores (Environmental, Social, Governance) on a 0-100 scale, with scores representing percentile ranks within industries. The methodology emphasizes transparency and objectivity, using publicly disclosed data rather than private submissions.

Data Integration: LSEG's integration of ESG data with its broader financial data infrastructure, including the Refinitiv Workspace platform, enables seamless analysis combining sustainability and financial factors. The company's extensive market data coverage facilitates analysis of relationships between ESG performance and financial outcomes.

Strengths and Applications: The percentile rank approach enables clear comparison within industries. The emphasis on publicly available data ensures transparency and replicability. LSEG's position within the London Stock Exchange Group creates synergies with exchange data and other LSEG services.

Further Reading

Detailed methodology documentation is available from each rating provider: MSCI at msci.com/esg-ratings, Sustainalytics at sustainalytics.com, S&P Global at spglobal.com/esg, FTSE Russell at ftserussell.com/esg, ISS at issgovernance.com, EcoVadis at ecovadis.com, CDP at cdp.net, Moody's at moodys.com/esg, Fitch at fitchratings.com/esg, and LSEG at lseg.com/esg.

References