How to check portfolio diversification with AI
Last updated August 2026
Short answer
This is one of the few analysis tasks where software has a genuine advantage, because the work is tedious, mechanical and nobody does it by hand.
Why a list of positions is not enough
An account summary shows funds, and funds are containers rather than exposures.
Three funds holding overlapping indexes produce one bet wearing three names.
The look-through, which resolves each fund into its underlying companies and adds them together, is the view that shows what you own.
The three views worth asking for
By company: the ten largest underlying holdings and their combined share of the total.
By sector: how much of the portfolio depends on one industry, which is where fund overlap usually shows up.
By geography: the share in a single country, which is invisible while that country performs well.
Count everything together
Workplace plan, IRA, taxable brokerage and any employer stock belong in one view.
Someone holding a conservative target-date fund at work and technology stocks elsewhere is neither conservative nor diversified.
The blend is what you own, and account boundaries are administrative rather than economic.
Try it in Walnut
Walnut connects to your brokerage accounts and reads the holdings directly, which is what makes a look-through across everything possible rather than theoretical.
Interpreting the answer
There is no threshold that makes a portfolio safe, and a useful test is what a 50% fall in the largest exposure would do to your plans.
Concentration you chose deliberately is a position. Concentration you discovered is a drift.
The distinction matters because the second kind tends to be largest exactly when it feels least risky.
What to do about it
Direct new contributions toward whatever is underweight, which corrects without selling.
Where a sale is needed, do it inside retirement accounts first, since no taxable event occurs there.
For employer stock, plan the reduction against vesting and tax rather than doing it all at once, and treat it as a decision with a schedule.
Questions that produce the useful answer
Look through every fund I hold and list the ten largest underlying companies with their combined weight.
Show me where two of my funds hold the same companies, and how much of the total that overlap represents.
What single event would hurt this portfolio most, and how much of the total is exposed to it.
What the answer cannot settle
Whether the concentration is a problem, which depends on your horizon and on what else funds your life.
Whether a position is worth holding, which is a question about the company rather than about the weight.
What to do next, since the useful output is a fact about your portfolio rather than an instruction.
Sources
Guidance on diversification and asset allocation is published by the SEC at investor.gov. Fund holdings are disclosed in filings available through EDGAR. Walnut is informational and is not an investment adviser. This guide is educational and not personalized investment advice.
FAQ
How do I check whether my portfolio is diversified?
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Look through the funds to the underlying companies and add up the largest positions across every account. Counting funds tells you nothing; a portfolio of six funds can hold the same twenty companies six times.
What should I ask for specifically?
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The ten largest underlying holdings across everything you own, with their combined weight, then the same by sector and by geography. Those three views catch nearly every concentration that matters.
Why does fund overlap matter so much?
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Because it is invisible in an account summary. An S&P 500 fund, a total-market fund and a growth fund look like three decisions and are largely one, with the same companies stacked rather than spread.
Does this need my accounts connected?
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It works far better with them connected, because the answer depends on holdings across every account rather than one at a time. Typing positions in by hand works and rarely gets done twice.
What counts as too concentrated?
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There is no universal line. A useful test is what a 50% fall in your largest exposure would do to your plans, and whether you would still be able to leave the rest alone.
What about employer stock?
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It should be counted alongside everything else, because it is usually the single largest concentration people carry and it correlates with the income paying for their life.
Is bonds-versus-stocks the same question?
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No. That is asset allocation, which is how much sits in each class. Diversification is how spread out you are inside them. A portfolio can be 60/40 and still hold four companies in one industry.
How often should I check?
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Once a year is enough, alongside a rebalance. Concentration builds through performance rather than through decisions, so it appears gradually and is easy to miss without a deliberate look.
What can the answer not settle?
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Whether the concentration is actually a problem, which depends on your horizon and what else funds your life, and whether any position is worth holding, which is a question about the company. The output is a fact about your portfolio rather than an instruction.
Does this work for a workplace plan?
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Only where the recordkeeper allows the account to be connected or you can export the holdings. Where it cannot, the fund names and their published holdings are enough to do the look-through by hand once a year.
Is a single total-market fund diversified enough?
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For the company-level question, largely yes, since it holds thousands of names across every sector. What it does not cover is geography, because a US total-market fund is a single-country position, and asset class, since it holds no bonds at all.