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What Is ESG Investing? A Sceptic's Guide to ESG Funds

By Thomas Lovas Lokoy

Researched and drafted with AI assistance from published sources; edited and published by NorwegianSpark SA.

Last updated: September 2026 · 9 min read

This article is for informational purposes only and does not constitute financial advice. Always consult a qualified financial adviser before making investment decisions.

Capital at risk. An ESG or sustainable fund can fall in value like any other. A sustainability label is a description of a screening process, not a measure of investment quality, and nothing here is personalised advice or an endorsement of any fund.

ESG investing attracts two equally unhelpful reactions. One says that choosing where your money goes is meaningless because someone else will buy the shares you decline. The other says a fund with "sustainable" on the label is doing something obviously good and needs no further examination.

Both skip the only question worth asking, which is mechanical rather than moral: what does this specific fund actually exclude, on what evidence, and what is left after it does? Answer that and the argument mostly resolves itself.

What ESG screening actually is

Start from an ordinary index — a broad market, cap-weighted, the sort described in who picks the index. An ESG index takes that starting universe and applies a filter based on environmental, social and governance data, then rebuilds the index from what survives.

The filter comes in three broad flavours, and the difference between them is enormous.

•Exclusion, or negative screening. Whole activities are removed: certain fuels, weapons, tobacco, gambling, and so on. Simple, transparent, and the easiest to verify by reading the holdings list.
•Best-in-class, or positive screening. Every industry stays in, but only the higher-scoring companies within each industry are kept. This can leave a fund holding the tidiest operator in an industry a reader assumed had been excluded entirely.
•Tilting. Nothing is excluded; higher scorers are simply given more weight and lower scorers less. The gentlest version, and the one whose holdings look most like the parent index.

A fund using the third approach and a fund using the first can carry very similar marketing language and hold conspicuously different things. This is the single most common surprise for people who buy on the label.

Where the ratings come from, and why they disagree

An ESG index needs a score for every company, and those scores are produced by rating providers using their own models. Different providers weight different factors, use different data sources, and answer different questions — some measure a company's impact on the world, others measure how exposed the company is to sustainability risks. Those are not the same question, and they can produce opposite conclusions about the same firm.

The practical consequence is that two credible ESG funds can hold different companies and both be honestly constructed. There is no single authority handing out a definitive score, and any fund implying otherwise is overselling.

This is where a sceptic's instinct earns its keep. The question is never "is this fund ESG?" It is "whose definition, applied how, and can I see the result?" The result is always visible: the holdings list is published.

The test that beats every marketing page

Do this before you buy anything with a sustainability label. It takes ten minutes and it is decisive.

•Open the fund's holdings list on the provider's own website. Not a summary, not a comparison site — the provider's.
•Open the holdings list of the plain index fund covering the same market from the same provider.
•Compare the top twenty in each. If they are nearly identical, you are holding a tilt, whatever the name says.
•Search the ESG fund's holdings for the two or three industries you personally assumed were excluded. If they are present, the screen is best-in-class, not exclusion.
•Read the fund's key information document for its stated objective and its stated screening approach in the fund's own words.
•Compare the ongoing charge with the plain version. That difference is what the screening is costing you every year.

Nothing on this list requires you to trust us, a rating agency, or a marketing page. It requires you to read two tables.

What it costs, and what it changes

QuestionThe honest answer
Does it cost more?Usually a little. Screened index funds tend to carry a higher ongoing charge than the plain version. Check both figures yourself.
Does it perform differently?It must, because it holds different things. Whether that difference is better or worse is not knowable in advance, and anyone who promises a direction is guessing.
Is it less diversified?Almost always, by construction. Removing companies narrows the universe, which can raise concentration — see index fund concentration risk.
Does it change corporate behaviour?Contested. Selling shares does not remove capital from a company that is not raising any. Voting and engagement by large fund managers is a more plausible channel than divestment.
Does it change what I own?Yes, definitely, and that is verifiable in an afternoon. This is the only claim on this list that survives full scepticism.

That last row deserves emphasis, because it is the strongest honest case for ESG funds. If you would rather not own certain industries, an exclusion-screened fund achieves exactly that, verifiably, at a small cost. That is a real outcome. It does not require you to believe your fund choice moves a share price.

The counter-argument, stated properly

The sceptic's case is strong and should be stated at full strength rather than in a strawman version.

Divestment by a small investor has no measurable effect on a large listed company's cost of capital. The shares you decline are bought by someone with no such scruples, at a price your absence has moved imperceptibly, and the company operates unchanged. Meanwhile you have paid a higher fee for a narrower portfolio, and you have relied on a rating whose methodology you did not read and whose competitors disagree with it.

Every part of that is defensible. The reply is not that it is wrong but that it answers a question most ESG investors are not asking. Many people are not trying to move a share price. They are declining to own something, which is a coherent preference that requires no theory of impact at all — and it is one of the few things in investing you can verify completely.

What genuinely does not survive scrutiny is buying a fund because the name sounds responsible, without opening the holdings list. That is paying a premium for a feeling.

What to check, and what to ask

•Which screening approach does the fund use, in the fund's own documents rather than in its advertising?
•Which rating provider's data does it rely on?
•Are the top twenty holdings materially different from the plain index fund for the same market?
•What is the ongoing charge, and how does it compare with the unscreened version?
•How many constituents does it hold compared with the parent index, and does the reduction concentrate it?
•Does the fund manager publish how it votes at company meetings — and do you care more about the voting than the screening?

The honest verdict

An ESG index fund is an index fund with a filter on the front. If the filter matches what you actually want excluded, you get a verifiable result at a modest cost, and the passive discipline that makes index investing work is entirely intact — the same automatic contributions, the same long holding period, the same refusal to trade on news.

If you have not read the holdings list, you do not know which filter you bought. That is the whole guide. Everything else is argument; this part is checkable, and it takes ten minutes.

About this article

This article was written by Thomas Lovas Lokoy — researched and drafted with AI assistance from published sources; edited and published by NorwegianSpark SA. YieldNav is operated by NorwegianSpark SA (org. 834 984 172), founded by Thomas Lovas Lokoy. We are not licensed financial advisers, and nothing here is personalised advice. Read our about page, editorial policy and affiliate disclosure.

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