Several managers list ETFs tracking the same index. “So does it matter which one?” Four things actually separate them: the expense ratio, the divergence from NAV, the fund's size — and the one people skip, the tax type.
1. How much is at stake. A 0.45 point gap in the expense ratio comes to ₩2.16 million on ₩10 million at 5% over 20 years (our calculation). Tax, meanwhile, swings 15.4 points at once.
2. Where the risk sits. Leveraged and inverse products appear in the same search results, and by statute an ETF may hold up to 30% in a single security — “an ETF means diversification” is not always true.
3. What order to check in. Is it a plain index fund → tax type → expense ratio → divergence → fund size → holdings. The expense ratio is not first.
This article covers what to look at and what each item means. For actual Korean figures — expense ratios, divergence, fund sizes — check product-level disclosures.
① The expense ratio — no bill ever arrives
It is the most-checked item, so start with why you never feel it.
“Funds pass along these costs to investors by deducting fees and expenses from NAV.”
— US Securities and Exchange Commission, ETF guidance. US framework, but the mechanism of costs coming out of NAV is the same.
Nobody asks you to pay. It comes out of the net asset value, daily, in small amounts, so there is no memory of having paid. The fee shows up as growth that didn't happen rather than money spent.
That illustration rests on assumptions (our own calculation). Grow 10 million won at 5% a year for 20 years and a 0.05% expense ratio leaves 26.28 million against 24.12 million at 0.50% — a gap of 2.16 million won. The return is assumed, so do not read the outcome as a forecast. The point is that a small percentage becomes a visible amount over a long horizon.
And the expense ratio is not the whole cost. The SEC notes that reinvesting distributions “can be more complicated than it is with mutual funds” and may mean “additional brokerage commissions.” Trading costs sit outside the ratio.
② Divergence — how closely the price tracks the real value
An ETF has two values: what it holds (NAV) and what it trades at (market price). The gap between them is what Korean investors call the divergence rate.
“For a variety of reasons, an ETF's market price may reflect a premium or a discount to the ETF's underlying value or NAV. Therefore, an investor may pay more or less than the NAV when buying shares or receive more or less than NAV when selling shares.”
— the same SEC page
| State | Market price is | When buying | When selling |
|---|---|---|---|
| Premium | above NAV | you pay more | you receive more |
| Discount | below NAV | you pay less | you receive less |
It cuts both ways. A premium is not simply bad — it works in opposite directions depending on whether you are buying or selling. Which is why a glance right before you trade is worth something.
“For a variety of reasons” is all the source says. Why the gap opens, and how much is too much, is not stated — so it is not stated here.
③ Fund size — and why we can't fully justify it
Two funds tracking the same index can differ greatly in size. With the sources available here we could not substantiate “bigger is better” from agency material. So we separate what is verified from what is not.
| The common claim | How this article treats it |
|---|---|
| “Bigger funds trade more easily” | not verified from agency source text |
| “Small funds risk delisting” | No criteria in the legislation — exchange rules (see below) |
| “Bigger funds have smaller divergence” | the SEC says only “a variety of reasons” |
What is verified is only this — an ETF is bought and sold on an exchange (the SEC definition) and its market price can drift from NAV. The relationship between fund size and that drift is not in this source. We did not fill the gap with guesswork.
④ The one people skip — tax type
People argue over 0.1 percentage points of expense ratio and then walk past a split between 0% and 15.4%. Under Korean rules:
| ETF type | Capital gain | Distribution |
|---|---|---|
| Domestic equity (Korean stocks only) | not taxed | 15.4% |
| “Other asset” (Korea-listed but bonds, commodities, derivatives) | 15.4% | 15.4% |
| Korea-listed overseas equity | 15.4% (holding-period basis) | 15.4% |
“Korea-listed” does not mean tax-free. The source states that “a Korea-listed ETF investing in bonds, commodities or derivatives rather than domestic equities is classified as an ‘other asset’ and 15.4% dividend income tax applies even to the capital gain.” What is inside comes before where it is listed.
— Kiwoom Asset Management, ETF tax guidance (19 August 2025). An asset manager's own material, containing links to its own products.
A 0.45pp fee gap came to 2.16 million won over 20 years. The tax type moves 15.4 percentage points at once. Which matters more depends on your holding period and realised amounts — but it is certainly not something to leave out while optimising the expense ratio. The full picture is in the ETF tax guide.
The same 10m won gain, and the tax is either nothing or 1.54m, depending on the type.
And products that only share the name
The same search results mix in quite different instruments. The SEC issued a separate alert on leveraged and inverse funds.
“these are specialized products that generally are not suitable for buy-and-hold investors.”
— SEC Office of Investor Education and Advocacy, investor alert (29 August 2023)
Checking “is this a plain index fund?” belongs before any argument about expense ratios. The structure of covered-call and leveraged products is covered in its own article.
Earlier this article said only that which matters more “depends on the holding period and the amount realised”. Here is where the line actually falls.
So, in order
| Step | What to look at | Basis |
|---|---|---|
| ① Plain index fund? | leveraged, inverse and covered-call funds behave differently | SEC alert |
| ② Tax type | domestic equity / “other asset” / overseas equity | private material |
| ③ Expense ratio | deducted from NAV daily | “deducted from NAV” |
| ④ Divergence | a glance right before trading | “a premium or a discount” |
| ⑤ Fund size | we could not verify the reasoning | — |
New to ETFs? Start with what an ETF is. Weighing Korea-listed against US-listed? See that comparison.
The legal skeleton of Korean ETFs, as the statutes have it
Plenty of writing explains ETFs; little of it separates what is legislation from what is convention. Here is the wording of Article 234 of the Financial Investment Services and Capital Markets Act and Articles 251 and 252 of its Enforcement Decree.
The legal definition of an ETF — three requirements
Act art. 234(1) — a collective investment scheme meeting all of the following:
1. it aims to be operated in linkage with changes in an index;
2. redemption of the beneficiary certificates or investment company shares is permitted;
3. … it is listed on a securities market within 30 days of establishment.
Requirement 2 is the key to understanding divergence. An ETF must, by law, permit redemption — it is not merely a listed share but a structure you can hand back at net asset value.
When the market price drifts from NAV, someone profits by redeeming or creating units, and that trade pulls the price back. The structural reason divergence does not widen indefinitely is in this provision.
But the statute does not say what percentage counts as normal. This article still gives no acceptable range.
Daily disclosure is a statutory duty
Decree art. 251
(1) The collective investment business entity shall publish the portfolio deposit file daily through the securities market.
(2) The exchange shall publish the fund's net asset value and its tracking error ratio (a measure comparing the change in NAV per unit against the change in the target index) at least once daily.
- Daily disclosure of holdings is a legal obligation, not industry practice — a real difference from ordinary funds.
- “Tracking error” and “divergence” are different measures. The statute defines tracking error as NAV change versus index change — how well the fund was run. Divergence is market price versus NAV — a problem at the moment you buy. Plenty of writing conflates them.
- NAV and tracking error are published by the exchange, not the manager — so exchange data is the primary source.
An ETF may hold up to 30% in a single security
Decree art. 252(1) permits a manager to invest “up to 30 per cent of the fund's total assets in a single security”, with 100 per cent for certain types and, where a security exceeds 30% of the index, up to that index weight.
This sits awkwardly with “an ETF means diversification.” Tracking an index requires concentration, so the limits are looser than for ordinary funds. An ETF following an index dominated by one large-cap can carry more than 30% in that single name. Worth looking at the holdings before buying — and thanks to art. 251 above, they are published daily.
Delisting criteria are not in the legislation
Act art. 234(4) says “listing and delisting … shall be prescribed by Presidential Decree,” but the relevant Decree provisions (arts. 251 and 252) contain no delisting criteria. The actual thresholds appear to sit in exchange listing rules.
So this article still prints no figure for “small funds risk delisting.” What is established is that you have to look in exchange rules, not legislation. Exchange rules are not legislation and do not open like provisions at the National Law Information Centre. If delisting risk on a specific product concerns you, check Korea Exchange disclosures and the manager's own notices.
Questions that remain
Just pick the lowest expense ratio?
Not on its own. What is verified is that costs come out of NAV and that trading costs are separate. And the tax type moves 15.4 percentage points in one step. Whether fees or tax dominate depends on holding period and realised amounts, so we do not generalise.
How much divergence is acceptable?
This source gives no threshold. The SEC says only that “a premium or a discount” can arise “for a variety of reasons” and offers no normal range. We did not invent one.
Should I avoid small funds?
This article does not judge. The usual arguments — liquidity, delisting, divergence — could not be substantiated from agency source text, and Korean delisting criteria were not verified either.
Why do funds tracking the same index perform differently?
This source cannot explain it. Only two things are verified: costs come out of NAV and market price can differ from NAV. Concepts such as tracking error are not on this page.
Is it fair to use US SEC material for Korean ETFs?
For structure, largely yes. That fees come out of the fund's value and that market price can drift from NAV are properties of the instrument. But regulation, disclosure and tax are separate systems — and tax is handled from Korean material.
The expense ratio leaves without a bill, and divergence works in opposite directions depending on whether you're buying or selling. Yet people optimise 0.1 percentage points of fees while skipping a tax type worth 15.4 — Korea-listed does not automatically mean tax-free.
Sources
- Korea Ministry of Government Legislation, National Law Information Centre — Financial Investment Services and Capital Markets Act, Article 234, in force 17 March 2026. Source for the three ETF requirements (index linkage, redemption permitted, listing within 30 days) and for paragraph 4 delegating listing and delisting to Presidential Decree.
- National Law Information Centre — Enforcement Decree, Article 251. Source for daily publication of the portfolio deposit file, the exchange's daily NAV and tracking-error publication duty, and the statutory definition of tracking error.
- National Law Information Centre — Enforcement Decree, Article 252. Source for the 30 per cent single-security limit and its exceptions.
- US Securities and Exchange Commission — ETFs. Source for “funds pass along these costs to investors by deducting fees and expenses from NAV,” “market price may reflect a premium or a discount… pay more or less than the NAV when buying or receive more or less when selling,” and the note that reinvesting distributions can be more complicated and may incur additional brokerage commissions. US framework.
- US Securities and Exchange Commission, Office of Investor Education and Advocacy — investor alert on leveraged and inverse ETFs (29 August 2023). Source for “generally are not suitable for buy-and-hold investors.”
- Kiwoom Asset Management (an asset manager's own material, not agency source text) — Kiwoom Lounge, “ETF taxes…” (19 August 2025; compliance review no. 2025-259). Source for the capital-gains exemption on domestic equity ETFs, “a Korea-listed ETF investing in bonds, commodities or derivatives is classified as an ‘other asset’ and 15.4% applies even to the capital gain,” holding-period taxation, and 15.4% on distributions. The same article links to the firm's own ETF products.
- Our own calculation. The 20-year fee illustration (10 million won, assumed 5% a year; 0.05% → 26.28 million, 0.50% → 24.12 million, a 2.16 million gap) is calculated by us on stated assumptions and appears in no source.
Where to check further
- The actual figures for the product you are buying — expense ratio, divergence, fund size and holdings differ product by product. Net asset value and tracking error are published daily by the exchange under Art. 251(2) of the Enforcement Decree, so Korea Exchange data is the primary source.
- Delisting criteria — Art. 234(4) delegates them to Presidential Decree, but the Decree does not contain them; they sit in the exchange's listing rules. Those rules are not legislation and do not appear in the law information centre, so check Korea Exchange disclosures and the manager's own guidance.
- The precise definition of “other assets” — the tax classification used here comes from an asset manager's own material. Confirm a specific product's tax treatment in its prospectus and National Tax Service guidance; the full structure is in ETF taxes.
As of July 2026. Structure and cost material comes from US SEC source text and the tax types from an asset manager's private publication, with the tier of each marked. The 20-year illustration is our own calculation on stated assumptions. Check product-level disclosures for actual Korean figures. New to ETFs? See what an ETF is; for tax, the ETF tax guide. This is general information and not financial advice. Investment decisions and their outcomes rest with the investor.
