Multi Asset Portfolio: Why Hold Several Asset Classes at Once

A multi asset portfolio holds several asset classes at the same time, such as stocks, government bonds, gold, commodities and the US dollar. The point is not to own more things, but to own things driven by different forces. When those forces differ, the asset classes rarely all fall at once, and the worst losses of the whole portfolio shrink. The trade-off: a fixed mix also gives up part of the return that stocks alone can deliver.

Five asset classes, five different return engines

Every asset class has its own "engine", the force that mainly drives its price:

• Stocks: company profits and growth.
• Government bonds (Treasuries): interest rates and the demand for safety.
• Gold: real interest rates, fear and central bank buying.
• Commodities: supply and demand for physical goods, including supply shocks.
• The US dollar: global money flows.

Because these engines respond to different things, a bad year for one is not automatically a bad year for the others. That is the whole reason to hold them together. Ten technology stocks may look like ten holdings, but they all run on the same engine: company profits.

Why correlation matters more than the number of holdings

The risk reduction from combining assets depends on correlation, a measure of how closely two assets move together. A correlation of 1 means they move in lockstep, 0 means they move independently.

The lesson illustrates this with arithmetic. Take ten assets, equally weighted, each swinging about 17% a year. The portfolio's yearly swing then depends almost entirely on how correlated they are:

• Correlation 0.8: about 15.4% a year. Owning ten assets removed almost no risk.
• Correlation 0.5: about 12.6%.
• Correlation 0.2: about 9.0%.
• Correlation 0 (fully independent): about 5.4%.

This is a formula-based illustration, not market data. The message is clear, though: adding more assets that move alike barely helps. Adding assets that move differently does most of the work.

What a multi asset portfolio did since 2007

The lesson then tests the idea on real market data from March 2007 to June 2026. It uses total return data for SPY (stocks), TLT (long-term Treasuries), GLD (gold), DBO (crude oil) and UUP (US dollar), rebalanced monthly, with no costs or taxes. These results are backtested and hypothetical, and past performance is not a guide to the future.

The worst fall dropped from a crash of 54.6% for stocks to 20.9% for the five-asset mix. In 2008 the mix lost 10.8% instead of 39.4%.

2022 is especially telling. The classic 60/40 portfolio lost 23.4%, more than stocks alone, because stocks and bonds fell together. The five-asset mix lost only about 5.7%. Having more than two engines made the difference.

The price of a fixed mix

The calmer ride came at a cost. The five-asset mix returned about 6.4% a year, against 10.9% for stocks: a gap of 4.5 percentage points a year in this hypothetical test.

The reason is structural. A fixed mix always holds every asset class at full weight, including the ones stuck in a long decline. Crude oil, for example, lost money over the whole period, yet it kept its 20% share. Diversification removed most of the risk, but it also diluted the return.

What a fixed mix lacks is any way to react when one engine stalls for years. That opens the next questions for anyone building such a portfolio: which asset classes really add something, how much of each to hold, and how to treat an asset class that is in a prolonged downturn.

Setting the right expectations

Holding asset classes together does:

• Make the worst fall much smaller.
• Spread your dependence across several engines instead of one.
• Make the plan far easier to stick with, because the losses are more bearable.

It does not:

• Prevent every losing year.
• Ensure that diversifiers always diversify. 2022 showed that stocks and bonds can fall together.
• Keep up with stocks in a long, calm bull market. In such periods a diversified portfolio trails.

That lag is the price of not depending on a single engine. Investors who know this in advance are less likely to abandon the mix at the wrong moment.

What to do with this

• List the asset classes you hold today and write the engine behind each one next to it.
• Count the engines, not the holdings. If most of your list runs on company profits, you hold one engine several times.
• Check how your portfolio behaved in 2022. If stocks and bonds both dragged it down, consider what other engines could have helped.
• Write down the trade-off you accept: a smaller worst fall in exchange for trailing stocks in strong bull markets.
• Look for assets that sat still or fell for years in a mix and ask whether a permanent full weight makes sense for them.

This article is based on Lesson 9.1 of our course Mastering Investments, where Module 1 is free.

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