Exclusion-Based ESG Indices and Fossil-Free Investing
What Are Exclusion-Based ESG Indices and How Do They Work?
Exclusion-based indices represent the oldest and most straightforward form of ESG indexing: remove companies or industries deemed unacceptable from a market portfolio and hold the remainder in market-cap weighted proportions. The approach is easy to explain, transparency is high, and implementation is simple — making exclusion indices the first ESG products adopted by many institutional investors. But exclusion-based investing has specific investment implications that are frequently misunderstood: it concentrates risk in whatever sectors are excluded, creates sector bets rather than ESG quality improvements, and produces material tracking differences when excluded sectors outperform the broader market.
Exclusion-based ESG indices remove companies or industries from a market portfolio based on specific activities or characteristics, holding the remaining eligible companies in market-cap weighted proportions without applying additional ESG quality screens to the retained universe.
Key Takeaways
- Exclusion indices are fundamentally sector bets: when excluded sectors (fossil fuels, tobacco, gambling) outperform, exclusion portfolios underperform; when they underperform, exclusion portfolios outperform.
- The universe retained after exclusions typically receives no ESG quality screen — a heavily-polluting manufacturer who does not produce tobacco or fossil fuels remains eligible.
- Fossil-fuel exclusion indices vary enormously in depth: some exclude only thermal coal mining; others exclude all fossil fuel exploration, production, refining, pipeline, and power generation.
- Engagement is not possible in exclusion-only strategies — investors who divest cannot engage.
- Faith-based, Islamic finance, and SRI-tradition exclusion lists have established decades of precedent for norms-based exclusion investing.
The Taxonomy of Exclusions
Exclusions in ESG indices fall into three categories:
Hard Exclusions (Absolute)
Hard exclusions apply regardless of revenue exposure level. Any involvement in the prohibited activity excludes the company. Common hard exclusions:
- Cluster munitions and anti-personnel landmines: Any production involvement — including component manufacture — triggers exclusion under most ESG index standards
- Biological and chemical weapons: Any involvement
- Anti-personnel mines: Any involvement
- Nuclear weapons: Applied variably — some indices exclude nuclear weapons for some countries (France, UK nuclear arsenals create complexity) while others exclude companies involved in US nuclear weapons maintenance
Hard exclusions are typically universal across ESG index methodologies because the activities violate core humanitarian law.
Revenue-Threshold Exclusions
Revenue-threshold exclusions apply when a company's revenue from a prohibited activity exceeds a specified percentage:
| Activity | Common Threshold Range |
|---|---|
| Tobacco production | 5%–25% |
| Thermal coal mining | 1%–25% |
| Oil sands extraction | 5%–10% |
| Civilian firearms | 5%–10% |
| Adult entertainment | 5%–10% |
| Gambling | 5%–10% |
| Alcohol | Not commonly excluded except in Islamic finance |
| Nuclear power | Excluded in some, retained in others (low-carbon argument) |
The revenue threshold level is a key methodology variable. A 25% tobacco revenue threshold retains tobacco retailers and distributors; a 5% threshold excludes them. A 25% thermal coal threshold retains diversified mining companies with coal exposure; a 1% threshold excludes them.
UNGC-Based Exclusions
Companies with documented, unresolved violations of the UN Global Compact principles are excluded through norms-based screening. This differs from the activity-based exclusions above — it is based on company behavior rather than industry membership.
Fossil Fuel Exclusion Depths
Fossil fuel exclusion is the most economically significant exclusion decision because the energy sector represents 4–8% of major market indices. Exclusion depth varies dramatically:
Level 1 (Minimal): Exclude thermal coal mining companies only. Energy sector weight reduction: ~0.1–0.2%.
Level 2 (Moderate): Exclude thermal coal mining, oil sands extraction. Energy sector weight reduction: ~0.5–1%.
Level 3 (Substantial): Exclude thermal coal mining, oil sands, coal-fired power generation, companies deriving >25% from oil and gas exploration and production. Energy sector weight reduction: ~2–3%.
Level 4 (Comprehensive): Exclude all fossil fuel exploration and production, coal mining, oil sands, fossil fuel power generation, fossil fuel pipelines and transport. Energy sector weight reduction: ~4–6%.
Level 5 (Paris-Aligned): EU PAB minimum: 50% carbon intensity reduction at inception, eliminate companies >1% revenue from thermal coal, >10% from oil sands, >50% from fossil fuel power. Energy sector weight reduction: ~5–7%.
Most "ESG" ETFs claiming fossil fuel exclusions operate at Level 2 or Level 3. Only PAB/CTB indices consistently operate at Level 5.
The Investment Implications of Exclusion
Sector Concentration Risk
Exclusion removes sectors from the portfolio, creating an unreplicated structural underweight. This is not a diversification improvement — it is a systematic sector bet. The magnitude of this bet is the excluded sector's weight in the parent index.
When the excluded sector performs well (the 2021–2022 energy rally, when energy stocks returned 55% while MSCI World returned -18%), exclusion portfolios underperform dramatically. This creates the standard criticism of fossil fuel exclusion: it underperforms when it is politically most difficult to defend.
No ESG Improvement Within Retained Universe
After exclusion, the remaining universe is typically held in market-cap weights with no ESG quality optimization. The best-managed company in the excluded sector is excluded; the worst-managed company in an included sector is retained. Exclusion reduces "bad" industry exposure without improving the ESG quality of the retained holdings.
Divestment and Engagement Trade-off
Investors who divest via exclusion cannot engage the excluded companies. This creates a genuine strategic choice:
- Exclusion: Clear values signal, no ongoing ESG risk from excluded activities, but no engagement leverage
- Engagement: Retain position to engage on ESG improvement, but ongoing exposure to excluded activities
Many ESG frameworks (Principles for Responsible Investment, IIGCC) favor engagement over pure exclusion for transition-stage companies, reserving exclusion for companies with no credible transition pathway.
Faith-Based and Islamic Finance Exclusion Traditions
Exclusion-based investing has deep roots in faith-based investment mandates:
Christian SRI tradition: Quaker investment funds in the 18th century avoided slave trade and weapons companies. Modern Christian SRI funds exclude tobacco, alcohol, gambling, and abortion-related activities.
Islamic finance (Shariah-compliant indices): Exclude companies deriving revenue from alcohol, tobacco, pork products, conventional financial services (interest-bearing), gambling, and weapons. Islamic ESG indices (MSCI Islamic Series, Dow Jones Islamic Market Index) have substantial AUM and represent a distinct exclusion tradition.
Jewish values funds: Typically combine ethical investment principles with Israel-related considerations.
These traditions predate modern ESG investing and established much of the institutional infrastructure for exclusion-based portfolio management.
Common Mistakes
Claiming fossil fuel exclusion while retaining fossil fuel service companies. Many "fossil free" indices exclude oil and gas producers but retain oilfield services companies (Schlumberger, Halliburton), pipeline operators, and LNG infrastructure. These companies are economically tied to fossil fuel expansion. "Fossil free" claims require specifying the exclusion scope.
Confusing exclusion with ESG quality. An exclusion index improves values alignment for investors who object to specific industries; it does not improve the ESG quality of retained holdings. A tobacco-free portfolio still includes companies with poor labor practices, governance failures, and high GHG emissions — just not tobacco.
Treating all exclusion indices as equivalent. A Level 1 thermal-coal-only exclusion fund and a Level 5 PAB-compliant fossil-free fund both carry "exclusion" labels but have fundamentally different ESG profiles and tracking characteristics.
Related Concepts
Summary
Exclusion-based ESG indices remove specific industries or activities from a market portfolio, holding the remainder in market-cap weights. Business activity exclusions range from hard exclusions (cluster munitions, any involvement) through revenue-threshold exclusions (tobacco, coal, oil sands) to norms-based UNGC screens. Fossil fuel exclusion depth varies enormously — from minimal thermal coal removal to comprehensive Paris-Aligned Benchmark standards. The investment implications of exclusion are consequential: sector bets, no ESG improvement in retained holdings, and loss of engagement leverage for excluded companies. Exclusion indices are appropriate tools for values alignment objectives but should not be confused with ESG quality improvement strategies.