What is asset allocation?
Last updated August 2026
Short answer
People spend far more time choosing between two similar funds than deciding how much should be in stocks at all. The second question matters more.
Why the mix dominates
Asset classes behave differently from one another far more than holdings behave differently within a class. Two large-cap US funds move nearly together; stocks and short-term bonds do not.
So the equity share sets the shape of the ride. A portfolio at 90% equities and one at 50% will have very different worst years, whatever funds are inside them.
That is why the allocation decision comes first and the fund selection second, rather than the order most people work in.
What should drive the choice
Time horizon. Money needed within a few years should not carry equity risk, because there may be no time to recover from a decline.
Capacity for loss, which is arithmetic: what a 40% fall would mean for your plans, not how it would feel.
Tolerance for loss, which is behavioural and only honestly measured after you have been through one. Most people overestimate it during good years.
Count everything together
Allocation applies to the whole portfolio: workplace plan, IRA, brokerage account and employer stock.
Someone holding a conservative target-date fund at work and individual technology stocks elsewhere is not conservative. The blend is what they own.
Employer equity deserves particular attention, because it correlates with the income that pays for everything else.
Try it in Walnut
Walnut reads your connected brokerage accounts and shows the allocation you actually have, rather than the one you set up originally.
How markets undo your decision
A rising stock market increases the equity share automatically. Several strong years turn a 70/30 portfolio into something closer to 80/20 with no action from you.
The change happens in the direction that increases risk, and it happens most in the periods where increasing risk feels most comfortable.
Rebalancing is the correction, and the reason to schedule it rather than decide each time is that the decision is hardest exactly when it matters.
Where each asset class belongs
Assets producing ordinary income, such as bonds and REITs, are generally better held in tax-deferred accounts.
Broad equity index funds are relatively tax-efficient and sit comfortably in a taxable account.
The allocation stays the same across accounts; only the location of each piece changes. That is asset location, and it is worth doing after the allocation is settled rather than instead of it.
Target-date funds as a packaged answer
A target-date fund holds a diversified mix and shifts it toward bonds as the named year approaches, packaging the allocation decision into one holding.
The two things to check are the expense ratio and the glide path, since funds with the same year on the label can hold quite different equity percentages at that date.
Holding one alongside other funds partly defeats the purpose, because the overall allocation is then whatever the combination produces rather than what the fund was designed to deliver.
Sources
The SEC's guidance for individual investors is published at Asset Allocation and Diversification. Walnut is informational and is not an investment adviser. This guide is educational and not personalized investment advice.
FAQ
What is asset allocation?
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The division of a portfolio between asset classes, principally stocks, bonds and cash. A 70/30 allocation means 70% in equities and 30% in bonds. It is the choice that determines most of how volatile the portfolio is and how it behaves in a downturn.
How do I choose an allocation?
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Start with when you need the money, then with how much decline you can hold through without selling. A horizon of twenty years supports far more equity than one of three, and an allocation you abandon in a bad year was the wrong one however well it modelled.
Is the old rule of 100 minus your age any good?
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As a starting point only. It was built when retirements were shorter and bond yields higher, and it ignores everything specific to you: other income, job security, pensions, and whether you have ever actually lived through a decline.
Does my 401(k) count separately from my brokerage account?
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No. Allocation is a property of everything you own together. Bonds in one account and concentrated equity in another is a single portfolio that is more aggressive than either account looks alone.
How is allocation different from diversification?
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Allocation is how much sits in each asset class. Diversification is how spread out you are inside them. A portfolio can be allocated 60/40 and still be undiversified if the equity half is four stocks in one industry.
How often should I revisit it?
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The allocation itself changes when your life does: a new horizon, a large expense, retirement approaching. The drift back to target is a separate and more frequent job, usually annually or on a set threshold.
Does a target-date fund handle allocation for me?
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Yes, that is the product: a diversified mix that shifts toward bonds as the date approaches. Check the expense ratio and the glide path, and note that holding one alongside other funds means your real allocation is the combination.