MSCI World vs. S&P 500: Which Index Belongs in Your Portfolio?
MSCI World or S&P 500 — on paper a comparison between a world index and a US index, in practice more like a comparison between a lot of US and even more US. Roughly 70% of the MSCI World consists of US stocks, and the top holdings are identical in both indices.
The decision still matters: it determines whether the remaining 30% of developed-market diversification sits in your portfolio or not — and how much your wealth depends on a single economy.
Overlap and allocation: a 70% shared base
The MSCI World holds around 1,400 stocks from 23 developed markets; the S&P 500 covers the 500 largest US companies. With a US weight of roughly 70% in the MSCI World, the S&P 500 is effectively contained within it to a large degree — Apple, Microsoft, Nvidia and co. lead both indices, just at different weights. Correlation between the two is correspondingly high.
The difference lies in the remaining ~30%: Japan, the UK, France, Switzerland and other developed markets that dilute the tech share and weight sectors like financials and industrials more heavily. Note that saving into both indices in parallel is not diversification — it only raises your US share. How much actually doubles up can be quantified precisely with an overlap analysis.
| Criterion | MSCI World | S&P 500 |
|---|---|---|
| Constituents | ~1,400 | 500 |
| Countries | 23 developed markets | USA |
| US share | ~70% | 100% |
| Top 10 holdings | US mega caps | identical US mega caps |
| TER of cheap ETFs | from ~0.12% | from ~0.03% |
Concentration risks, ETF overlap and look-through analysis – free with MoneyPeak.
Return and risk: what history shows — and what it doesn’t
Over the past 10 and 15 years the S&P 500 led, driven by US tech — by roughly 1–2 percentage points per year depending on the period. Over very long horizons, both indices sit at historically around 7–8% p.a. nominal. The S&P 500’s outperformance is a phenomenon of the recent past, not a law: in the 2000s after the dot-com bust, the broader world index did better.
On the risk side, the S&P 500 is the more concentrated bet — one country, one currency zone, a higher tech share. On costs it wins: S&P 500 ETFs start at around 0.03% TER, World ETFs at around 0.12%. On a €100,000 portfolio that is roughly €90 a year — real, but not a deciding factor next to the allocation question. For German investors both are taxed identically: 30% partial exemption, an effective 26.375% flat tax on the rest.
Decision matrix: which index suits which investor
The choice boils down to a few questions:
- You want maximum simplicity and accept market-cap weighting: MSCI World — the 30% non-US portion is free insurance against US-specific risks.
- You deliberately want to go all-in on the US: S&P 500 — cheaper, more concentrated, but an explicit country bet.
- You want to control the US share yourself: combine the S&P 500 with an MSCI World ex USA — more precise than any either-or decision.
What matters is the whole portfolio: anyone holding US single stocks or a Nasdaq ETF alongside a World ETF quickly ends up at 80%+ US. A look-through analysis makes the US concentration risk visible before the next drawdown does.
Frequently asked questions
How large is the overlap between MSCI World and S&P 500?
Roughly 70% of the MSCI World is US equities, and the large S&P 500 names are practically all contained in the MSCI World. The top 10 holdings of both indices are identical.
Does it make sense to invest in MSCI World and S&P 500 at the same time?
Not as diversification: the combination only raises the US share beyond the ~70% of the MSCI World. It only makes sense if you deliberately want to overweight the US.
Which index has performed better historically?
Over the past 10–15 years the S&P 500, driven by US tech. Over very long horizons both sit at around 7–8% p.a. nominal, with alternating leadership phases — the world index led in the 2000s, for instance.
Concentration risks, ETF overlap and look-through analysis – free with MoneyPeak.