You have $2,000 invested toward a career break 15 years away. A stress test for a bad year leaves one portfolio with $1,375 and another with $1,730 — a $355 gap. Both own exactly the same broad stock fund. Why the difference?
The fund has the same return in both portfolios. The second portfolio puts fewer dollars into that fund. Before comparing tickers, decide how much of your goal rides on stocks.
Give each dollar a job
Asset allocation is the split of your whole investment portfolio among asset classes, such as stocks, bonds and cash. The percentages add up to 100%.
Here, the $2,000 is the whole portfolio for that goal, with emergency reserves and nearer spending kept separate. Cash inside the portfolio counts toward its allocation. A long time horizon gives you time to keep saving, but losses can still put the goal out of reach.
A portfolio weight is a holding's or asset class's percentage of that total. Put $1,200 of the $2,000 into stocks and the stock weight is $1,200 ÷ $2,000 = 60%. One fund can account for most of your money.
A stock fund and an individual stock both belong in the equity, or stock, allocation. An ETF can hold stocks, bonds or a mixture. “ETF” tells you the container; look inside it to find the allocation.
The mix changes the damage
Try three starting mixes. Say stocks lose 40%, bonds gain 5% and cash earns nothing over one year. These are total returns: they include income as well as price changes. No money is added, withdrawn or moved between assets during the year.
The 80/15/5 mix loses $625, or 31.25% of its starting value. The 40/50/10 mix loses $270, or 13.5%. Owning the same fund does not mean taking the same risk.
For the middle mix — 60% stocks, 30% bonds and 10% cash — follow the dollars:
| Asset | Start | End |
|---|---|---|
| Stocks | $1,200 | $720 |
| Bonds | $600 | $630 |
| Cash | $200 | $200 |
The stocks lose $480: $1,200 × 40%. The bonds add $30: $600 × 5%. That leaves $720 + $630 + $200 = $1,550, a $450 loss. Divide $450 by the starting $2,000 and the loss is 22.5%.
The shortcut uses the beginning weights, written as decimals: 60% becomes 0.60. Multiply each return by its weight, then add:
For the middle mix: (0.60 × −40%) + (0.30 × 5%) + (0.10 × 0%) = −22.5%.
Bonds are loans whose market values can fall too. Change their return to −10% and the middle mix loses $540: $480 from stocks plus $60 from bonds. A stress test gives you a possible loss, not a ceiling. What bonds do in a portfolio covers choosing bonds for the job.
Start with the goal, not your age
Would a $450 loss leave your goal intact?
Your risk capacity and risk tolerance both matter: what your finances can absorb and what you can live with. Being calm about a loss does not make the missing money available.
An allocation has to fit your income, spending needs and goals:
- Income: Reliable earnings and room to save make a setback easier to repair. Losing your job as markets fall makes it harder.
- Withdrawals: A bill due soon leaves less room for losses than money you can leave invested.
- The goal: A career break you can shorten or delay has more flexibility than a payment with a fixed amount and date.
Suppose you can replace up to $300 from spare income without delaying the break. In the original test, the $270 loss fits that cushion; $450 and $625 do not. The middle mix fails this constraint even if its percentages look comfortable.
The smallest loss does not settle the choice. Less in stocks means less money benefiting when those stocks rise.
Your savings and investments still need to fund the goal. If that demands more risk than you can carry, saving more, spending less or moving the date changes the problem. Wishing for higher returns does not.
Familiar shortcuts include 60/40 — 60% stocks and 40% bonds — and “100 minus your age” as the stock percentage. Neither knows your bills. Two people born on the same day can need different allocations.
Retirement also has more than one deadline. Your first year's spending and money for much later years have different jobs. Once withdrawals begin, the timing of losses matters too; sequence-of-returns risk explains why.
A target is a choice you revisit
Your target allocation is the mix you intend to hold. Strategic asset allocation means maintaining that target across market conditions as a long-term plan.
A lost job, a changed goal or an approaching spending date can justify a new target. A frightening headline does not, by itself, change what the money is for.
The contents of each bucket still matter. Putting the whole stock portion in one company leaves you dependent on that business. Correlation and diversification examines how holdings work together. Rebalancing covers restoring weights after they drift.
Try the same test on a different mix for the $2,000:
- The job: A career break in 15 years, with a $300 cushion to replace losses.
- The mix: Choose stock, bond and cash percentages totaling 100%.
- The loss: Apply −40%, +5% and 0%, then compare the dollar loss with $300.
More than one mix can pass this test. The useful answer explains what the loss would mean for the goal.
In short
- Give the money a job before choosing its stock, bond and cash mix.
- The same fund can do different damage depending on how much money you put in it.
- A rule of thumb is a starting question, not a personal answer.
- A stress test is a scenario to plan around, not a forecast or a limit on losses.