Asset allocation: choosing your mix of stocks, bonds and cash

What asset allocation is, why the stock, bond and cash mix drives most of a portfolio's swings, and how time horizon and risk tolerance shape it.

Part of the Investing Foundations track on Agenticks. About 10 minutes, written for a beginner reader.

Read first: Bonds explained: coupons, yields and why prices move, Risk and return, the basic tradeoff, Diversification in plain language.

Last reviewed .

Key takeaways

Asset allocation is how you split your investments between broad types of asset, mainly stocks, bonds and cash. Each of these is an asset class, a group of investments that tend to behave alike. A mix is often written as two or three numbers: 60/40 means 60% stocks and 40% bonds, and 70/20/10 adds 10% cash. The diversification lesson is about spreading money within and across asset classes so that no single holding can sink you. Asset allocation is the bigger decision sitting above that. Before you choose a single fund, the split between stocks, bonds and cash has already decided most of how bumpy your ride will be.

The three classes play different roles. Stocks are ownership in companies. They have offered the most growth potential over long periods and also the deepest falls along the way. Bonds are loans to governments and companies. They usually swing less than stocks and pay regular interest, though their prices fall when interest rates rise. The bonds lesson covers why. Cash here means savings accounts, money market funds and very short-term government bills, often called cash equivalents. They rarely lose value but tend to lag inflation over long stretches. The classes do not move in lockstep. In many bad years for stocks, bonds and cash have held up better, which is the whole point of mixing them. That is a tendency, not a law: there have been years when stocks and bonds fell together.

To see how much the mix matters, take two portfolios of $100,000 and put them through the same rough year.

Worked example: two mixes in the same bad year

In this made-up year, stocks fall 30%, bonds gain 3% and cash earns 2%. Portfolio A is 90% stocks and 10% bonds. Portfolio B is 40% stocks, 50% bonds and 10% cash.

A: $90,000 in stocks (90,000 x 0.70)$63,000
A: $10,000 in bonds (10,000 x 1.03)$10,300
A: total at year end$73,300 (-26.7%)
B: $40,000 in stocks (40,000 x 0.70)$28,000
B: $50,000 in bonds (50,000 x 1.03)$51,500
B: $10,000 in cash (10,000 x 1.02)$10,200
B: total at year end$89,700 (-10.3%)
Gap between the two mixes$16,400 in one year

Illustrative returns chosen to show the mechanics, not a forecast or a record of any real year.

Now flip it. In a good year where stocks gain 20% and bonds and cash earn the same as before, Portfolio A ends at $118,300 (+18.3%) and Portfolio B at $109,700 (+9.7%). The mix that fell less in the bad year also rose less in the good one. That is the risk and return tradeoff in its plainest form: there is no mix that captures all of the upside and none of the downside. Research points the same way. A well-known 1986 study of 91 large US pension funds found that their long-run policy mix explained, on average, more than 90% of how their quarterly returns rose and fell over time. Later work added an important qualification: that figure is about the swings over time, not about which fund ended up with the highest return, where security choice and costs also play a part. For the question of how bumpy a portfolio feels, though, the mix does most of the work.

The mix sets the size of the swings

Picking good investments matters, but the split between stocks, bonds and cash decides most of how far a portfolio can fall in a bad year and how far it can climb in a good one.

Two things shape a sensible mix: time horizon and risk tolerance. Time horizon is how long the money can stay invested before it is needed. Money for a house deposit in two years has little time to recover from a fall, so a deep drop just before you need it would be locked in when you withdraw. Money for retirement 30 years away has time to sit through several bad years. The same person can have both kinds of money, with a different mix for each. Risk tolerance is how much decline you can live with, both on paper and in your stomach. A mix that looks fine in a spreadsheet can be unbearable when the account is down a quarter of its value, and selling in a panic turns a temporary fall into a permanent one. A mix you can hold through a bad year does more for you than a bolder one you abandon halfway down.

Two practical points often get missed. First, allocation describes all of your investments together. If one account holds $30,000 of stocks and another holds $20,000 of bonds, the portfolio is 60/40 even though neither account is. Second, the mix is only part of diversification. Inside the stock portion, spreading across many companies and industries still matters, because a stock allocation made of one sector can move as a single block. Cash also has a job outside the mix. Money for emergencies is usually kept apart from the invested portfolio, so a bad market year never forces a sale to cover a car repair or a gap between jobs. The start here track covers building that cushion before investing.

You will often see age-based rules of thumb, such as holding 100 minus your age in stocks, or 110 or 120 minus your age for a more growth-tilted version. By the first rule a 30-year-old would hold 70% stocks and a 60-year-old 40%. These are heuristics, quick starting points, not answers. They capture one real idea, that a longer horizon can usually carry more stock, and ignore almost everything else: what the money is for, whether you have a pension or other steady income, how much you already have saved, and how you react to losses. Target-date funds apply a similar idea automatically, moving from stocks towards bonds as a chosen year approaches. A mix can reasonably change over time, as a goal gets closer or a life changes. What tends to go wrong is changing it because of what the market just did: moving to cash after a fall or piling into stocks after a strong run is market timing under another name, and it usually means selling low and buying high. Changing the mix because the plan changed is a different thing from changing it because the headlines did. Once a mix is chosen, markets will slowly push it off target. Keeping it where you set it is called rebalancing, covered in the rebalancing lesson.

Stocks
Shares of a single company, An index fund tracking the S&P/TSX Composite
Bonds
A 10-year government bond, A fund holding investment-grade corporate bonds
Cash
A high-interest savings account, A money market fund

You understand asset allocation

You can explain what a stock, bond and cash mix is, why it drives a portfolio's swings, and how time horizon and risk tolerance shape it.

Check your understanding

What does a 60/40 portfolio usually mean?
60% in stocks and 40% in bonds. The first number is conventionally stocks and the second bonds.
In the worked example's bad year, the 90/10 mix fell about 27% and the 40/50/10 mix about 10%. What explains most of the gap?
How much of each portfolio was in stocks. Stocks fell 30% in the example, so the portfolio with 90% in stocks took far more of that fall.
Someone needs their money for a house deposit in 18 months. Which statement fits how time horizon works?
A short horizon leaves little time to recover from a fall, which is why short-term money usually leans on bonds and cash. A deep fall just before the money is needed would be locked in when it is withdrawn.
What is the main weakness of a rule like "hold 100 minus your age in stocks"?
It ignores goals, other income and how the person actually handles losses. Two people of the same age can have very different needs, so the rule is only a rough starting point.

Common questions

What is asset allocation in simple terms?
Asset allocation is how you divide your investments between broad types, mainly stocks, bonds and cash. A 60/40 mix, for example, means 60% stocks and 40% bonds.
Why does asset allocation matter so much?
Stocks, bonds and cash behave very differently in good and bad years, so the split between them sets most of how far a portfolio rises or falls. A well-known study of large pension funds found their policy mix explained most of the variation in their returns over time.
Is there a correct asset allocation for my age?
No single mix is correct for an age. Rules such as 100 minus your age are rough heuristics. Time horizon, goals, other income and how you react to losses all matter, and a mix you abandon in a downturn does not help.

Terms defined in this lesson

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Agenticks Learn is general education. It is not financial, investment, tax or legal advice, it does not take your situation into account, and nothing on it is a recommendation to buy, sell or hold any security or to open any account. Examples use illustrative numbers. Investing involves risk, including losing money you put in, and past performance does not predict future results. Tax rules and limits change; the official sources linked in each lesson are the final word.