ESG Screening Methods Explained: From Exclusions to Impact

The term "ESG investing" encompasses a remarkably diverse range of practices. A fund that excludes tobacco companies, a fund that scores every company in its universe on environmental criteria, a fund that actively engages with management to improve governance, and a fund that invests exclusively in renewable energy infrastructure all might be described as "ESG" — yet their methodologies, exposures, and likely outcomes are fundamentally different.

This guide explains the main screening and integration approaches in detail. Understanding the distinctions is essential for investors who want to align their portfolios with their values without sacrificing investment rigour.

1. Negative Screening (Exclusions)

Negative screening — removing certain companies or sectors from an investment universe — is the oldest and most widely used ESG approach. It is the historical basis of "ethical" or "socially responsible" investing.

Common exclusion categories:

• Tobacco: Manufacturing of tobacco products. Applied broadly, may also exclude distributors.
• Weapons and defence: "Controversial weapons" (cluster munitions, landmines, chemical and biological weapons) are almost universally excluded by self-described ESG funds. "Conventional weapons" exclusions vary — some funds exclude all defence contractors, others only controversial weapons manufacturers.
• Gambling: Casino operators, online gambling platforms, bookmakers.
• Alcohol: Producers and distributors (less common than tobacco exclusion).
• Fossil fuels: Coal extraction (most common); oil and gas exploration (less universal); thermal coal electricity generation. Degree of exclusion varies enormously — "pure coal" exclusions remove perhaps 1% of the global index; "no fossil fuels" exclusions remove ~5–15%.
• Adult entertainment: Pornography production and distribution.

Impact on portfolio and tracking error:

Exclusions typically remove 5–20% of the investment universe. The impact on portfolio characteristics depends heavily on what is excluded and the sector weight of those companies in the benchmark. In a period (2022) when oil and gas companies outperformed substantially, portfolios with fossil fuel exclusions meaningfully underperformed. In periods of strong technology performance, exclusions of these sectors have minimal impact on returns.

Tracking error: Negative screening introduces tracking error relative to the parent benchmark. A fund excluding fossil fuels, tobacco, and weapons might have annualised tracking error of 0.5–2% versus an un-screened equivalent.

Additionality question: Negative screening in secondary markets (buying and selling listed equities) does not directly starve excluded companies of capital. A UK investor who refuses to hold Shell shares does not reduce Shell's ability to operate. The primary mechanism of impact is indirect: aggregated exclusion changes a company's cost of capital at the margin and affects its social licence. This is real but modest.

2. Positive Screening (Best-in-Class)

Positive screening (or "best-in-class" screening) takes a different approach: rather than excluding sectors, it selects the highest-rated ESG companies within each sector, including historically "problematic" sectors.

Under this approach, an oil company that scores significantly higher than its peers on environmental management, community relations, and governance might be included in a positively screened fund — while a technology company with poor labour practices, supply chain ESG failures, or governance issues might be excluded.

Arguments for positive screening:

• Engages with every sector of the economy rather than leaving "dirty" sectors entirely outside the ESG investor base.
• Provides incentives for companies within traditionally problematic sectors to improve — the "carrot" rather than the "stick" of exclusion.
• Avoids the accusation that exclusion-only funds are simply avoiding complexity.
• Maintains broader diversification than strict exclusion-based approaches.

Arguments against:

• Allows companies in inherently harmful industries to receive "ESG" branding based on relative performance within their sector — a tobacco company can score as "ESG" if it is the least bad tobacco company.
• Is heavily dependent on ESG rating methodology, which varies enormously between rating agencies.
• Less intuitively "ethical" to investors with strong value-based positions on certain industries.

3. ESG Integration

ESG integration means incorporating environmental, social, and governance factors into conventional financial analysis — not as an ethical screen but as material factors relevant to assessing a company's financial prospects and risk profile.

Under an integration approach:

• A fund manager considers a mining company's water usage and community relations when forecasting its operating cost trajectory and licence-to-operate risk.
• Governance factors (board independence, audit quality, executive compensation structure) are assessed as indicators of management quality and agency risk.
• Regulatory exposure — a company's carbon intensity relative to upcoming emissions regulations — is modelled into cash flow projections.

ESG integration does not necessarily exclude any company or sector. It is financially motivated analysis, not values-based. The argument is that ESG factors are material financial risks that traditional financial analysis may underweight.

Most mainstream active fund managers would claim to practice some form of ESG integration, but the depth and consistency varies enormously. Key questions for fund manager due diligence: How specifically do ESG factors affect investment decisions? Can you show a case where ESG analysis caused you to change a position?

4. Norms-Based Screening

Norms-based screening excludes companies that violate internationally established standards, regardless of their sector.

The primary norms framework used is the UN Global Compact, which establishes 10 principles across human rights, labour standards, environmental responsibility, and anti-corruption. Companies found to be in systematic violation of these principles — for example, through confirmed use of forced labour, systematic environmental violations, or corruption convictions — are excluded.

Norms-based screening is often combined with negative screening as part of a multi-layered ESG approach. It is distinct from exclusion in that it applies across all sectors based on behaviour rather than sector membership.

Controversy monitoring is closely related: funds using norms-based screening continuously monitor companies for "ESG controversies" — events that may indicate a violation of the norms. Companies involved in major environmental disasters, labour abuses, or governance failures may be excluded or flagged for review mid-period.

5. Thematic Investing

Thematic ESG investing involves concentrating the portfolio in specific sustainability themes — areas of the economy that benefit from the transition to a more sustainable world.

Common sustainability themes:

• Clean energy: Solar, wind, grid infrastructure, battery storage, green hydrogen.
• Water: Water treatment, purification, infrastructure, efficiency technology.
• Circular economy: Waste reduction, recycling technology, remanufacturing.
• Biodiversity and nature: Sustainable agriculture, forestry, ocean conservation-linked businesses.
• Low-carbon transition: Energy efficiency, electric vehicles, low-carbon industrial processes.

Thematic funds are by nature concentrated — they hold a narrower universe of companies related to a specific theme. This concentration introduces:

• Higher volatility: Thematic funds can outperform spectacularly when their theme is in favour and underperform severely when it is not (clean energy funds underperformed significantly in 2022 as interest rates rose and elevated rates hurt growth valuations in capital-intensive infrastructure).
• Valuation risk: Popular themes attract capital, which can drive valuations to levels that price in significant long-term growth — creating downside risk if that growth does not materialise at the expected pace.
• Theme duration risk: The energy transition is a multi-decade theme but is not linear. Policy changes, technology cost curves, and competitive dynamics mean that which companies within the theme will win is uncertain.

6. Impact Investing

Impact investing — discussed in more depth in our dedicated guide — occupies the most demanding end of the ESG spectrum. The three defining criteria (intentionality, measurability, and additionality) distinguish it from all the approaches above.

• Intentionality: The investment is made specifically to generate a positive social or environmental outcome.
• Measurability: The outcome must be measurable — not stated as a goal but demonstrated through defined metrics (e.g., tonnes of CO2 avoided, number of affordable housing units built, microloans disbursed).
• Additionality: The outcome would not have occurred without the investment. Buying shares in a solar company on a secondary market is not impact investment — the company already exists and the capital goes to the seller, not the company. Providing development capital to build new solar capacity has additionality.

Impact investing is predominantly practiced through private markets (direct lending, PE, real assets) where additionality can be clearly demonstrated. Public market "impact" funds should be scrutinised carefully for whether they genuinely meet the additionality criterion.

7. Shareholder Engagement

Engagement is an alternative to exclusion as a mechanism for improving corporate behaviour. Rather than selling shares in a company with poor ESG practices, engaged investors retain their shares and use the rights of ownership (voting at AGMs, direct dialogue with boards and management) to push for improvement.

The largest institutional shareholders — Legal & General Investment Management, BlackRock, Norges Bank (Norwegian Government Pension Fund) — have explicit engagement programmes and vote against management at hundreds of AGMs per year on issues including climate disclosure, executive pay, board diversity, and governance.

The evidence on engagement effectiveness is growing: Academic studies find that coordinated engagement by multiple large shareholders produces measurable improvements in targeted ESG metrics. For individual investors, access to engagement is primarily through funds with explicit engagement commitments.

Choosing Between Approaches: Questions to Ask

For investors trying to select an appropriate ESG approach, the key questions are:

1. What is your primary motivation? Value alignment (negative screening), financial risk management (ESG integration), or real-world impact (impact investing)?
2. How important is diversification and benchmark tracking? Thematic funds are more concentrated; broad ESG integration funds track more closely.
3. What is your view on engagement vs exclusion? Do you want companies excluded from your portfolio, or do you believe engaged institutional ownership produces better outcomes?
4. How much tracking error are you prepared to accept? Strict exclusions combined with thematic tilts can introduce significant tracking error.
5. What is your time horizon? Long-term transition themes (clean energy, water) may underperform in short-term rate cycles but generate returns over 10+ year horizons.

All investments carry the risk of capital loss. ESG-screened portfolios may underperform un-screened equivalents over specific periods. Past performance is not a guide to future returns. ESG ratings are not standardised and vary between providers. This guide is for information only and does not constitute financial advice.

How Global Investments Can Help

Global Investments works with HNW clients to design sustainable investment strategies that reflect their values without sacrificing investment discipline. We can help you select appropriate approaches — exclusions, integration, thematic, or impact — based on your financial objectives and ethical priorities, evaluate ESG fund quality beyond marketing claims, and ensure that your sustainable portfolio has coherent exposures and genuine accountability to stated principles. Contact us to discuss your approach to responsible investing.