Work in amounts before percentages
Suppose an illustrative portfolio has $800 in Fund A and $400 in Fund B. Fund A reports 6% in Company X and Fund B reports 9% in the same company. The indirect amounts are $48 and $36, making $84 in total. Against the $1,200 portfolio, that is 7% exposure to Company X.
Adding 6% and 9% to claim 15% would be wrong because the percentages describe different fund balances. The correct method multiplies each fund balance by its holding weight, adds the resulting amounts and divides by the whole portfolio value. The same approach can be used for an industry when the classifications are comparable.
Use documents with dates
Holdings lists are snapshots. A fund report from one month and a website list from another may not describe the same market conditions. Record the date of each list and the date of the fund values used. If only the largest holdings are disclosed, the calculation is incomplete rather than proof that smaller overlaps do not exist.
Names also need checking. Different share classes or listings may refer to the same underlying company, while similar names may refer to unrelated issuers. Use identifiers where available and avoid merging entries just because their labels look familiar.
Extend the calculation without losing the denominator
Add a direct $120 holding in Company X to the earlier example. The combined portfolio is now $1,320, and exposure to the company is $204: $84 through the funds plus $120 directly. Dividing $204 by $1,320 gives about 15.45%. It would be wrong to add $120 to the exposure while leaving the denominator at the earlier $1,200.
This matters when a worksheet is updated piecemeal. Keep one master total and make every exposure row refer to it. If a new account is added, update both the holdings and the total before interpreting the percentages. A forgotten cash balance can also distort the result, depending on the scope chosen for the review.
For industry exposure, check that the funds classify companies consistently. One provider may place a business in technology while another uses a communication-services category. Adding the labelled percentages without checking definitions can create false precision. Where the categories cannot be reconciled, keep separate estimates and explain the limitation rather than forcing them into a single exact percentage.
Interpret the result carefully
FINRA's concentration-risk guidance encourages looking inside funds to identify shared positions. An overlap is not automatically an error. It becomes relevant when the combined exposure is larger or more narrowly focused than the investor intended.
For example, owning a broad fund and a specialist fund may deliberately add exposure to one area. The calculation makes that extra exposure visible. Calling both products diversified does not remove the added concentration in the combined portfolio.
Keep a small worksheet with fund value, holding weight, implied amount and source date. Note any missing data separately. Rounding an estimate to a sensible level is better than presenting many decimal places based on stale or partial information. The purpose is to understand the shape of exposure well enough to review it, not to suggest that a public holdings snapshot can reproduce the portfolio perfectly in real time.
