Three-Fund Portfolio: Adapting It for a European Investor
Three ETFs, a bit of discipline, and you're done: that's the promise of the three-fund portfolio, a recipe popularized by Anglo-Saxon investment guides. Its logic seems foolproof on paper — a domestic equity ETF, an international equity ETF, a bond ETF — and it works well for those living in the United States, where the domestic market already represents the bulk of global market capitalization.
For an investor based in Belgium or elsewhere in Europe, the same formula conceals a problem that doesn't appear at first glance: what does the "domestic" market actually weigh in the global economy, and how much weight should it be given in a portfolio supposedly representing the entire world?
Key Takeaways
- The three-fund portfolio combines a domestic equity ETF, an international equity ETF, and a broad bond ETF, according to Saxo's guide to ETF strategies.
- Replacing the concept of a home country with market-cap weighting globally yields a distribution close to 89% developed markets and 11% emerging markets, according to Curvo's analysis of ETFs accessible to Belgian investors.
- Each additional ETF line adds one transaction per contribution, meaning additional brokerage fees.
- A single all-world ETF (such as ACWI IMI or FTSE All-World) can suffice: three lines are optional, not mandatory.
- The historical returns presented below describe past performance, not a promise for the future.
What Is the Three-Fund Portfolio, and Where Did the Idea Come From?
The principle is intentionally minimalist. According to Saxo's guide to ETF strategies for beginners, "for those who prioritize absolute simplicity, the three-fund portfolio uses just three broad ETFs to create a globally diversified investment mix." The three building blocks are always the same: an ETF focused on the investor's domestic equity market, an ETF on international equities, and a broad bond ETF.
The thinking behind this architecture is straightforward: diversification reduces a portfolio's overall risk. An ETF spread across multiple sectors cushions sector-specific shocks that a portfolio concentrated in a few holdings would suffer fully, as Curvo notes in its analysis of ETFs available to Belgian investors.
Three Lines, One Goal
What the three-fund portfolio seeks to achieve isn't complexity but coverage: equities from around the world for growth, bonds to cushion downturns. The number of lines — three — isn't a hard rule; it's a compromise between simplicity and diversification. The follow-up question is how to allocate these three lines when you don't live in the country that accounts for 60% of global stock markets.
Why the Geographic "Home Plus Rest of World" Formula Doesn't Work for Smaller Markets
A Generic Example Modeled on the American Approach
In its guide, Saxo proposes a concrete implementation example for a European investor: 40% in the STOXX Europe 600, 30% in MSCI World excluding Europe, and 30% in a European aggregate bond ETF. The structure faithfully mirrors the American scheme — where "domestic equities" means "American equities" — by simply translating "domestic equities" to "European equities," without questioning the principle of a distinct "home" component separate from the rest of the world.
The problem isn't that this allocation is absurd in itself. It's that it assigns 40% of the portfolio to a geographic zone chosen because the investor lives there, not because it represents 40% of global stock market value.
An Alternative That Ignores Country of Origin
Curvo proposes a comparison point constructed differently: to replicate the actual weighting of markets by global market capitalization, the split between developed and emerging market ETFs hovers around 89% / 11%. This logic knows no "home country" category: it weights each region according to its measured economic size, not the investor's nationality.
Applied as-is, it produces very different results from 40/30/30: Europe doesn't occupy a special place; it's simply diluted within the 89% of developed markets, alongside the United States, Japan, or Canada.
A More Coherent Model, But Not Static
This market-cap weighting isn't a fixed solution you implement once and forget. Curvo makes this explicit: "the right allocation is something you need to manage yourself. It can become more demanding because the ratio evolves over time." Today's 89/11 won't be the same five years from now, as the relative weight of emerging and developed markets shifts.
One, Two, or Three ETFs: How Many Lines Does Your Portfolio Really Need?
Once the weighting logic is clear, a practical question remains: do you really need three separate lines, or will a single all-world ETF suffice? Three options exist, each with different tradeoffs between coverage, cost, and maintenance.
| Option | Companies Covered | Annual Cost (TER) | Transactions Per Contribution |
|---|---|---|---|
| 1 All-World ETF (e.g., SPDR MSCI ACWI IMI, Vanguard FTSE All-World) | 5,981 companies across 47 countries (ACWI IMI) or roughly 3,300 to 3,780 stocks depending on source (FTSE All-World) | 0.17% (ACWI IMI) or 0.22% (FTSE All-World) | 1 |
| 2 Developed + Emerging ETFs (e.g., SPDR MSCI World + iShares Core MSCI EM IMI) | 1,308 companies from 23 developed countries + 3,105 companies from 24 emerging countries | Varies depending on the two funds selected | 2 |
| 3 Developed + Emerging + Bond ETFs | The two above, plus a broad bond ETF | Varies depending on the three funds selected | 3 |
_Data: Curvo._
The bond line isn't questioned by this reasoning — it serves a different purpose, cushioning fluctuations, not representing a geographic region.
The choice between one, two, or three lines boils down to simple tradeoff: holding two ETFs instead of one adds a transaction to each investment cycle, meaning extra brokerage fees, according to Curvo. Three lines add another transaction and rebalancing across three fronts instead of one.
Regardless of how many lines you choose, selecting the funds themselves follows complementary criteria, detailed below.
What Historical Returns Say About Each Component (Read With Caution)
The figures that follow describe past performance over a given period. They don't indicate what each component will deliver in coming years.
The Developed Markets Component
The MSCI World index delivered an average annual return of 10.8% since 1979, according to data reported by Curvo. For the SPDR MSCI World ETF, which replicates this same index, the same source cites 10.4% in reconstructed performance over the same period. Both figures are calculated from the index's history — this fund didn't exist in 1979 — and the gap between them, roughly half a percentage point, mainly highlights that a return quoted to the nearest tenth of a percent over nearly fifty years remains an estimate, not an exact measurement.
The index tracked by Vanguard FTSE All-World, which covers both developed and emerging markets, shows 8.7% since 2005. The MSCI ACWI IMI, yet another all-world index, shows 7.7% since 1994. These three figures don't measure the same thing: different indices, different starting periods, slightly different compositions.
The Emerging Markets Component
The index tracked by iShares Core MSCI Emerging Markets IMI offers a more concrete order of magnitude in reconstructed performance: €10,000 invested in 1994 would have exceeded €46,000 by early 2026, or roughly 5.0% average annual return — notably lagging the developed indices over their own reference periods.
The Bond Component
The index tracked by Xtrackers II Eurozone Government Bond (0.09% TER) returned an average of 3.1% annually between 1999 and 2023 in reconstructed performance. In a bond ETF, prices move inversely to interest rates, and this effect is more pronounced for longer-maturity bonds. This mechanism, combined with volatility far lower than equities, allows bonds to cushion portfolio swings rather than match its returns.
Practical Checklist: How to Choose Each ETF for Your Three-Fund Portfolio
Once you've decided on weighting — geographic or by capitalization — it remains to select the funds themselves. A few non-tax criteria help sort through the offerings:
- Minimum assets under management: consider only ETFs with at least €100 million, a threshold that excludes funds that are still too new or too obscure, according to Curvo.
- Physical replication for long-term holding, rather than synthetic replication whose mechanism is harder to verify.
- Index coherence with the intended component: an "emerging markets" ETF must actually cover emerging markets, not a restricted subset that merely bears the name.
- TER consistency across lines: a three-fund portfolio loses much of its appeal if one line costs 0.07% and another 0.50% without justification linked to market complexity.
None of these criteria depends on the investor's country of residence: they apply equally to developed, emerging, or bond components.
FAQ: Questions Beginners Ask About the Three-Fund Portfolio
Does the ratio between developed and emerging markets shift on its own without selling anything? Yes. If emerging markets advance faster than developed markets over a given period, their portfolio weight increases mechanically, even without any purchases or sales. This silent drift is why you need to review allocation periodically rather than treating it as set in stone.
Is a single ETF enough for a beginner? For modest capital, a single all-world ETF mainly avoids over-complicating savings that don't yet justify multiple lines to track and rebalance separately.
How do you fund this portfolio without trying to time the market? Systematic investing means placing a fixed amount at regular intervals, which eliminates the stress of choosing entry timing. During the 2020 volatility, maintaining monthly contributions automatically bought more shares at March's lows and fewer at December's highs, without any emotional decision-making needed.
Is the three-fund portfolio compatible with a "core-satellite" approach? This approach splits a portfolio between a stable 70–80% core of broad ETFs and 20–30% satellites in more specialized ETFs. The three-fund portfolio can play exactly this core role, with satellites added around it without upending the basic structure.
Conclusion: The "Right" Global Component Never Stops Changing
The TERs of broad ETFs already vary considerably from one fund to another, as shown by the gap between ACWI IMI's 0.17% and FTSE All-World's 0.22%. This difference highlights that the "cheapest" or "broadest" line in a three-fund portfolio isn't fixed over time: new products can emerge, and existing fund fees can change.
This raises a question the initial portfolio construction leaves open: does reviewing your ETF selection every year or two make more sense than locking it in for your entire investing life?
--- This article is published for informational purposes only and does not constitute investment advice. Consult an authorized financial advisor before making any investment decisions.
