Active ETFs: how they work and what they deliver

In depth11 min read · 15 sources

Active ETFs combine the wrapper of an exchange-traded index fund with a manager who selects and weights the holdings. They are usually cheaper than traditional active funds and, in the US, more tax-efficient, but they have to clear the same hurdle: delivering more than the index after costs. Here you will learn how active ETFs are built, which transparency rules apply in the US and in Europe, how fast the market is growing and how much excess return the costs require.

What an active ETF is and what it is not

An ETF is, first of all, just a fund wrapper: its units are traded on the stock exchange and are issued and redeemed by authorized participants through creation and redemption (the basics are in the article ETF basics). What is inside the wrapper is a separate question:

The boundary is blurred. Easley et al. (2021) distinguish ETFs that are active in form (they aim to generate alpha) from those that are active in function: narrow building blocks such as sector or thematic ETFs, from which investors build active portfolios. According to their activeness index, the range on offer increasingly consists of highly active products. The ETFs that are active in form have the highest fees and the highest portfolio turnover, and their inflows follow performance. A smart beta ETF is active in a rule-based sense, but it is not an active ETF: it follows an index that anyone can look up.

Transparency: daily, quarterly or via an agent

An index ETF reveals its holdings through the index itself. An active ETF has to disclose them so that market makers know the fair value and can quote tight prices. But in doing so, it also discloses its strategy. The rules on this differ:

• US, standard case: since the SEC's ETF rule 6c-11 of 2019, ETFs relying on it must publish their holdings as of the previous day's close before the market opens on every business day. Active ETFs without daily transparency do not fall under the rule and need individual exemptive relief (SEC 2019).
• US, non-fully transparent ETFs: the first such approval, on May 20, 2019, went to a model in which only an agent of the authorized participants knows the basket via a confidential account, and the fund disseminates a verified indicative value every second; only securities that trade on US exchanges at the same time are permitted. Behind the caution lies the concern that third parties could replicate the strategy or trade ahead of the fund (Dechert LLP 2019).
• Ireland, UCITS ETFs: for a long time, the Central Bank of Ireland only authorized an ETF if it disclosed the identity and quantity of its holdings daily. Since the revision of its UCITS Q&A in April 2025, periodic disclosure is also sufficient: holdings as of the end of each quarter no later than 30 business days afterward, provided that enough information is available daily for effective arbitrage, and to authorized participants and market makers without discrimination (Doyle and Deane 2025).

For investors in Europe, the Irish rule is what counts, because many of the ETFs offered there are domiciled in Ireland. With a semi-transparent ETF, you only see the holdings with a delay. Market makers are then less able to hedge their risk, so the exchange price can deviate further from the net asset value. That is one reason to trade with limit orders (see order types and execution).

Creation, redemption and the tax advantage in the US

In the primary market, authorized participants exchange large blocks of ETF units for a basket of securities or for cash. The US rule also allows custom baskets that differ from the portfolio for this purpose, provided the fund has written policies for how they are put together (SEC 2019). This is where a tax advantage lies: if a US fund hands over securities instead of cash on a redemption, it realizes no capital gain that it would have to distribute to investors. Used deliberately, this is called a heartbeat trade: an authorized participant subscribes for units and shortly afterward redeems them in exchange for holdings with large unrealized gains.

Moussawi et al. (2025) estimate that in recent years this tax efficiency gave long-term US investors 1.05 percentage points a year more after tax than mutual funds, and see it as a key reason why wealthy investors are moving money from mutual funds into ETFs. This is not tax advice. There is also a cost advantage: on the exchange, you buy without a front-end load, but you pay the bid-ask spread instead.

Strategies: from research enhanced to covered call

• Research enhanced index: the portfolio stays close to the index, with many holdings and small overweights and underweights based on in-house analysis. The aim is a small but steady outperformance with a deliberately low tracking error.
• Covered call and income: the fund holds equities or an index and sells call options on them (covered call). The premiums increase the distributions, but upside price gains are capped. The result is a different risk-return profile, not security selection.
• Active bond ETFs: in bonds, active management is more widespread, because indices are hard to replicate and managers steer duration, credit quality and sectors; why the results differ from equities is shown in the article active or passive in bonds and commodities.
• Concentrated and thematic portfolios: a few holdings based on the manager's conviction, often with a high active share. Here, the result depends most heavily on skill and capacity.
• Clones of mutual funds: providers launch the strategy of an existing active fund as an ETF as well. Du et al. (2023) find in the US that such clones do not take inflows away from the parent fund and, thanks to its reputation, raise more money than comparable active ETFs, even without better performance.

How big the market is

Sources for the table: (ETFGI 2026; ICI 2026). The conversions accounted for 2.4% of US ETFs' net issuance over this period.

In seven months, the assets of active ETFs grew by 35.6%, and inflows were almost twice as high as in the same period of the previous year. Part of this is reallocation: mutual funds were converted into ETFs, and investors switched wrappers for tax reasons (Moussawi et al. 2025). Growth says nothing about the quality of the managers. Above all, it shows that the wrapper has become cheaper and more convenient.

Worked example: how much alpha the extra costs require

Three ways of investing $100,000 for ten years in an equity market that returns 6% a year before costs. The costs are illustrative; the expense ratio is deducted from the fund's assets every year, the front-end load once on purchase. Spreads and taxes are left out.

For advanced readers: information ratio, time to proof and capacity

The information ratio shows how hard it is to prove even 0.43 percentage points. Its t-statistic only grows with the square root of time:

• Capacity: Berk and Green (2004) explain why skill and weak average results are compatible. As assets grow, the return of active strategies falls, and investors keep moving money to successful managers until no predictable excess return is left. In their calibration, around 80% of managers have at least enough skill to earn back their fees. A successful active ETF attracts inflows, and with them precisely the size that can eat up its lead.
• Many small bets: according to the fundamental law of active management by Grinold and Kahn (2000), the expected information ratio rises with forecasting skill and the number of independent bets. A research enhanced approach therefore needs less skill per bet than a concentrated portfolio.
• Front-running with full transparency: if you disclose daily, you make your reallocations visible; if a manager builds a position over several days, others see it after the first day (front-running). For small positions in liquid stocks this probably costs little, for large positions in thin markets more; this is an assessment.
• Closet indexing: an active ETF with a low active share and a high R² relative to the index is an expensive index fund. Check the tracking error and active share before you pay for active management.

What the research shows

• Sharpe (1991) shows arithmetically that the average actively managed dollar must lag the passive one after costs. This applies to active ETFs just as it does to mutual funds; the wrapper changes the costs, not the arithmetic.
• In Europe, over the ten years to June 2026, 94% of active equity funds lagged their benchmark (SPIVA Europe 2026).
• Fama and French (2010) find that only a few US equity funds achieve enough excess return to cover their costs; before costs, there is genuine inferior and superior performance in the extreme tails.
• Schizas (2014) found for the first active ETFs that they fluctuated more than passive ETFs and ended up performing similarly, but often outperformed mutual funds in terms of average return.
• Easley et al. (2021) expect the growing market share of more active ETFs to put pressure on fees across the whole industry; Moussawi et al. (2025) and Du et al. (2023) show that taxes and the reputation of well-known funds help determine inflows, not just performance.

Limits and common mistakes

• The wrapper is not the strategy: low costs and exchange trading do not turn a weak strategy into a good one.
• Check the benchmark: some active ETFs name a benchmark that is easy to beat. Compare with the market the fund actually invests in; style analysis helps with this.
• Option premiums are not alpha: the high distributions of a covered call ETF are paid for with capped price gains.
• Short history: many active ETFs are young, and a few years prove little. With converted funds, part of the history often comes from the time as a mutual fund, with different costs.

How Portfolio Lab calculates it

Portfolio Lab does not rate managers, but it gives you tools to examine an active ETF. In the Backtest you set it against a benchmark and see the tracking error, information ratio and alpha. Style analysis explains its monthly returns by a mix of style indices following Sharpe (1992); calculated on a rolling basis and out of sample, it shows whether a selection return remains after deducting the style mix. The factor regression breaks the return down into Fama-French factor returns plus momentum and delivers an alpha with a t-statistic; a high R² with an alpha close to zero points to an expensive index fund. Under Securities you can see the replication method of ETFs. The prices are exchange prices, not net asset values, and with a short history all estimates are uncertain.

This article explains a method; it is not investment or tax advice. Worked examples are simplified and rounded. All terms in the glossary.