Most private investors only use two to three asset classes: stocks, bonds, maybe cash. Professional portfolios work with8 to 10 different building blocks. The difference in risk-adjusted returns is huge — and it can be proven with 50 years of market data.
This article analyzes all ten relevant asset classes based on their historical return, volatility, Sharpe ratio, maximum drawdown and - most importantly - their correlations with each other. Because real diversification does not start with the number of positions, but with the independence of their return drivers.
The return-risk map: Where does each asset class stand?
Each asset class has its own profile of expected return and risk. The data from 1972 to 2020 shows clear patterns:
US stocks (total return): 9.30% p.a.with 15.25% volatility and a Sharpe ratio of 0.37. The growth engine of every portfolio, but with a brutal maximum drawdown of -51.12% in the 2008 financial crisis. Those who invested at the peak in 2007 took until 2013 to get their investment back.
Gold: 7.86% p.a.with 20.07% volatility and a Sharpe ratio of 0.22. Not an impressive return at first glance. But gold has a unique property: its correlation with stocks is only0.02— practically zero. This makes gold the most valuable diversifier in the entire asset class universe. More about this in ourdetailed gold analysis.
Commodities (GSCI): 7.51% p.a.at 17.13% volatility. The highest maximum drawdown of all asset classes at -72.02% - an asset class that requires strong nerves. But currently the GSCI/DJIA ratio is at onehistoric low, comparable to 1970. Such lows were historically followed by massive commodity rallies that lasted 10 to 15 years.
US Treasuries:The safe haven in deflation and crisis scenarios. The correlation with US stocks is-0.66— a historically extreme value. Since 1880 the average has been +0.2. This negative correlation makes Treasuries the ideal crash protection. But be careful: this relationship reverses when inflation rises.
Emerging Markets Stocks:Higher return potential than industrialized countries, driven by demographic dynamics and economic growth. The valuation on a CAPE basis is currently well below the US market — a countercyclical signal that historically indicates outperformance.
Stocks in industrialized countries (EAFE):The bridge between the US market and emerging markets. Fundamentally valued more favorably than the S&P 500, with moderate correlation to the US market. A position that reduces geographic concentration without sacrificing equity returns.
The bond world: Four building blocks with different roles
Not all bonds are the same. Four different bond classes fulfill fundamentally different functions in the portfolio:
US Treasuriesare the ultimate crisis hedge - government bonds have risen in every stock crash of the last 50 years. Their extremely negative correlation with stocks (-0.66) makes them a stabilizer in deflation scenarios. But with inflation they become a risk: rising interest rates mean falling bond prices.
Global bondsoffer broader diversification across countries, currencies and maturities. The diversification effect is more moderate than with pure US Treasuries, but the concentration risk is lower. A useful component for European investors that spreads currency risks.
US corporate bonds(Corporate bonds) offer higher returns through the credit spread — the premium for the risk of default. But in crises, this bond class behaves more like stocks: the correlation skyrockets when markets come under stress. Not a reliable diversifier in extreme scenarios.
TIPS (Treasury Inflation-Protected Securities)are inflation-indexed US government bonds whose coupon is linked to the consumer price index. If inflation rises unexpectedly, the face value rises - the only bond building block that works reliably in an inflation scenario.
The Correlation Matrix: The Hidden Network
The true strength of a multi-asset portfolio lies not in the individual returns, but in the correlation matrix. The data from 2000-2020 reveals a fascinating network of dependencies and independences:
Gold / US stocks: 0.02— The Holy Grail of Diversification. This near-zero correlation means that whatever happens in the stock market, gold moves independently. No other building block offers this property with a positive long-term return.
US Stocks/Treasuries: -0.66— A historical anomaly. The long-term average since 1880 is +0.2. The current extreme negative correlation is a product of central bank policy and may reverse with inflation regime changes. Anyone who bases their portfolio solely on this relationship is taking a structural risk.
Commodities/Treasuries: -0.23— A natural contradiction. When inflation rises, commodity prices rise — and bonds fall. This negative correlation makes commodities a natural hedge against bond risk during inflation.
Gold / Treasuries: +0.38— Both rise in crises, but for different reasons. Treasuries rise by fleeing to safety, gold by fleeing the financial system. Both benefit in deflation, only gold benefits in inflation.
Warning: Correlations are not static.In crises, correlations converge — asset classes that are normally independent suddenly fall at the same time. This phenomenon must be taken into account when constructing a portfolio. Only asset classes with structurally different return drivers offer real diversification, even in extreme scenarios.
What the data means for portfolio construction
Four key findings for optimal portfolio construction emerge from 50 years of market data:
Finding 1: Use at least 6-8 asset classes.The efficiency line moves up to the left with each additional uncorrelated asset class — more return with less risk. The jump from 2 to 6 asset classes brings the greatest diversification gain. Furthermore, the marginal effects are smaller but still positive.
Finding 2: Reduce stock concentration.A portfolio with 60% US stocks and 40% US bonds (the classic 60/40) is not a diversified portfolio — it is a bet on the US market and falling interest rates. Anyone who mixes in international stocks, emerging markets, gold and raw materials dramatically reduces the cluster risk.
Finding 3: Build in tangible assets.Gold and raw materials belong in every robust portfolio. Not as speculation, but as a structural diversifier. The correlation data shows: No other building block offers the combination of positive long-term returns and low equity correlation that gold delivers.
Insight 4: Build for different scenarios.A portfolio that only works in one market regime is not a robust portfolio. The data shows: The correlation between stocks and bonds can reverse. Those who have built for inflation AND deflation will survive any regime change. Find out more aboutMonetary policy and inflation scenarios.
Conclusion: data instead of opinion
50 years of market data don’t lie. They show that most investors invest too concentratedly, not diversified enough and too opinion-driven. Optimal portfolio construction is not a game of chance or gut feeling — it is a mathematical optimization based on historical returns, volatilities and correlations.
The ten asset classes presented in this article are the building blocks from which any robust portfolio is constructed. The art is not in finding the best individual building block - but in finding the combination that creates the best overall picture. This doesn’t require intuition, but rather data.