Diversification that helps:
100% US stocks vs a simple diversified mix
“Don’t put all your eggs in one basket” is vague advice. This study puts numbers on it — comparing a 100% US stock portfolio to a 60/20/20 diversified mix over a stylized 2015–2024 path. The goal is to show the real trade-off between growth, drawdowns, and the mix you can actually hold through a bad year.
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What the 2015–2024 comparison shows
Stylized paths for 100% US stocks vs a 60/20/20 mix (US equity + international equity + investment-grade bonds), rebalanced annually. Numbers illustrate the trade-off — not a precise backtest of any single fund.
- Higher headline CAGR when the US market leads.
- Simplicity — one regional market to track and understand.
- Works well for investors with a long horizon and high risk tolerance.
- Broad UCITS S&P 500 or MSCI USA trackers are cheap and liquid.
- Deeper holes when the US corrects — harder to hold through.
- Single-country risk: one policy, one currency, one cycle.
- Behavioral failure becomes more likely when drawdowns are severe.
- No cushion from uncorrelated assets during equity crashes.
What we compared and how
Both portfolios use broad index-style exposure. The comparison isolates the effect of asset mix — not manager skill, timing, or fund selection.
Broad US total market or S&P 500-style index exposure. For European investors, this maps to UCITS ETFs such as iShares Core S&P 500 (CSP1) or Vanguard S&P 500 (VUSA).
60% US equity + 20% international equity (ex-US) + 20% investment-grade bonds. Rebalanced once per year back to target weights. All implemented with UCITS funds.
- Data is modeled on monthly total returns (price plus dividends) in USD, with taxes and fund expense ratios ignored to isolate the impact of the asset mix itself.
- Both portfolios start at 1.00x (lump sum at the beginning of 2015). No ongoing contributions are modeled.
- The chart and table use stylized 2015–2024 paths that are representative of the period’s dynamics — not a precise NAV backtest of any specific fund combination.
- European investors also face FX drag when converting EUR to USD to buy USD-denominated exposure. That additional layer is covered in the FX drag study.
- Different time windows, funds, and rebalancing implementations change exact numbers. The direction of the growth vs drawdown trade-off is the point — not the precise figures.
Normalized growth: 100% US stocks vs 60/20/20 mix
Both start at 1.00x. The gap shows what you trade for smoother drawdowns — some upside in strong US bull markets, in exchange for a shallower fall when equity markets correct.
Stylized illustration for conceptual clarity. Real outcomes depend on the specific funds chosen, currency effects, fees, taxes, contribution timing, and exact rebalancing implementation.
What the chart is actually showing you
In this pattern, US stocks pull ahead over time because the US market outperformed most alternatives during this period. That is real — but it comes with a cost: the holes are deeper. When equity markets corrected sharply (2018 Q4, 2020 March, 2022), the 100% US portfolio fell harder and took longer to recover.
The diversified mix grew more slowly, but it fell less in bad periods. Bonds and international equities did not perfectly offset US equity losses — they rarely do — but they cushioned the ride enough that the drawdowns were meaningfully smaller.
The key question is not which line wins by a few basis points. It is whether the drawdowns during the US-only path would have caused you to sell, pause contributions, or abandon the plan entirely. If yes, the diversified path likely produces a better real-life outcome — even if the theoretical CAGR is lower.
When diversification helps — and when it disappoints
Diversification is not unconditionally good or bad. The answer depends on your time horizon, savings rate, and most importantly, your actual behavior during drawdowns.
- You know from experience you struggle to hold through large equity drawdowns without acting.
- Your savings rate is strong — protecting the compounding base matters more than maximum upside.
- You want multiple uncorrelated return drivers instead of a single regional bet.
- You have a shorter effective horizon where a large drawdown near the end is damaging.
- You prefer slightly lower returns you can stick with over “optimal” returns you might abandon.
- You benchmark yourself against the single best-performing market instead of your own plan.
- You are early career, highly risk-tolerant, and your main risk is undershooting long-run growth.
- You hold many overlapping funds that look diversified but track nearly the same index.
- You expect diversification to eliminate crashes — it reduces pain, it does not erase it.
- You add complexity (many funds, frequent rebalancing) and pay extra fees for minimal benefit.
Diversification shapes the distribution of outcomes into a range you can live with for decades. A simple two- or three-fund UCITS portfolio — global equity plus a bond allocation if wanted — is already real diversification. The goal is a mix you will hold through ugly years, not a complex structure you will second-guess at the worst moment.
Growth vs drawdown: side by side
Stylized numbers consistent with the 2015–2024 chart path. The CAGR difference is real but modest; the drawdown difference is where the behavioral impact concentrates.
| Series | CAGR | Max drawdown | Worst 12-mo |
|---|---|---|---|
| 100% US Stocks | ~11.5% | ~-23.0% | ~-18.0% |
| 60% US / 20% Intl / 20% Bonds | ~9.5% | ~-16.0% | ~-12.0% |
The ~2pp CAGR gap is the cost of diversification. The ~7pp improvement in worst drawdown is the benefit. Whether that trade makes sense depends entirely on whether you would have held the concentrated portfolio through the worst 12-month stretch — or sold.
European investors can implement a 60/20/20 mix with two or three UCITS ETFs. Use TradingView to compare drawdown charts across US equity, global equity, and bond trackers before committing. Pick a broker with transparent FX pricing — it matters when buying USD-denominated exposure.
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Guides and studies to go deeper
The practical rules: what to diversify, what to ignore, and why fake diversification is worse than none.
A closer look at what bonds actually add — and when they disappoint in the same environment as stocks.
MSCI World vs FTSE All-World: the one-fund global default, done correctly with UCITS wrappers.
Global equity plus bonds plus rebalancing: a structured plan for European investors using compliant funds.
Concentration risk vs simplicity: a practical decision framework for your first or second fund.
Simple rules to keep allocations from drifting into accidental bets — without constantly checking your portfolio.
What actually changes when you rebalance once a year versus never touching your allocation again.
Why broad index funds are the building block of most sensible diversified portfolios.
Diversification fails when friction makes you stop contributing. The drag from fees compounds silently.
The real cost of a diversified UCITS fund shows up in tracking, spreads, and tax — not just the headline fee.
Common questions
How many ETFs do I actually need to be diversified?
Not many. A broad global UCITS equity ETF — such as an MSCI World or FTSE All-World tracker — plus a high-quality bond ETF is already real diversification. Most well-run portfolios use two to four broad, low-cost funds, not a long list of overlapping products.
Does diversification always reduce my returns?
It can lag the single best-performing market over a given decade because you spread exposure across assets and regions. In exchange, you reduce dependence on one bet and typically soften drawdowns. If diversification lets you stay invested and keep contributing through bad years, it can improve your real-life outcome even if the headline CAGR looks slightly lower on paper.
Should I also diversify across multiple brokers?
Usually no. For most investors one solid, regulated broker is enough — two at most for redundancy. Diversification should happen inside the portfolio through the mix of funds, not by scattering small positions across many platforms and creating unnecessary complexity.
How often should I rebalance a diversified portfolio?
Many investors rebalance once a year or use simple drift bands — for example, rebalancing when any allocation drifts more than 5pp from target. Frequent rebalancing is usually unnecessary. The important part is having a rule and following it, not constant tweaking.
Which UCITS ETFs work for a diversified portfolio as a European investor?
The 60/20/20 mix in this study can be implemented entirely with UCITS-compliant funds. For US equity: iShares Core S&P 500 (CSP1) or Vanguard S&P 500 (VUSA). For international equity: a developed markets ex-US or FTSE All-World tracker. For bonds: a short- or intermediate-duration EUR-hedged aggregate bond fund. All are available through regulated EU brokers with no PRIIPs complications.
Educational content only. Not personalized investment or tax advice.
Investments can lose value and past performance does not guarantee future results. Chart data is stylized and representative — not a precise backtest of any specific fund or index. You are responsible for your own decisions and for confirming the tax and legal rules that apply in your country.