Two Funds, One Company: Calculate Your Combined Exposure

Owning two funds does not necessarily mean owning two independent sets of investments. Both may hold the same large companies. The portfolio question is not just whether a name appears twice, but how much of the investor’s total money ultimately reaches that name through all the holdings combined.

This exercise uses fictional labels AAA, BBB, CCC and DDD. They are not tickers or recommendations. The lists are complete within the example and sum to 100% for each fund. That condition matters: a calculation made from a fund’s ten largest holdings can only describe the supplied subset unless the missing holdings are handled explicitly.

Read the fund weights before the portfolio weights

Broad Fund holds 40% AAA, 30% BBB and 30% CCC. Focus Fund holds 50% AAA, 20% BBB and 30% DDD. At the fund level, the shared positions are AAA and BBB. A common weighted overlap calculation adds the smaller weight in each shared position: 40% for AAA plus 20% for BBB, giving 60%.

That 60% is a comparison between the two fund holding lists. It is not a statement that the investor has 60% of the account in duplicated assets, and it does not identify the investor’s weight in AAA. To answer those questions, the actual allocation between the funds must enter the calculation.

Add the investor’s allocations

Suppose a $20,000 portfolio puts 70% into Broad Fund and 30% into Focus Fund. Broad receives $14,000 and Focus receives $6,000. The AAA exposure through Broad is $5,600, while the AAA exposure through Focus is $3,000. Together they make $8,600, or 43% of the entire portfolio.

The remaining combined weights are 27% BBB, 21% CCC and 9% DDD. They reconcile to 100%. The calculation for each company is the sum of its fund weight multiplied by the portfolio allocation to that fund. For AAA, that is 0.70 × 0.40 plus 0.30 × 0.50 = 0.43.

Having two fund names on the statement does not alter the fact that this fictional portfolio places 43% in one company. It also does not prove that the holding is unsuitable. The result identifies an exposure that needs to be assessed against the investor’s own objectives and limits rather than treated as diversified simply because there are two funds.

Change the allocation and keep the overlap label honest

Move to 30% Broad and 70% Focus without changing either fund’s holdings. AAA rises to 47%, BBB falls to 23%, CCC falls to 9% and DDD rises to 21%. The funds’ pairwise overlap remains 60%. Their composition did not change; the investor’s allocations did.

This distinction is important when a tool offers an allocation slider. A stable pairwise overlap number can be correct even as the combined company weights change. A tool should explain which result belongs to the funds and which belongs to the investor’s allocation. Treating every percentage as the same type of diversification score makes both harder to interpret.

Add cash without losing the denominator

Suppose the investor holds 10% of the whole account in cash and allocates the remaining 90% between the funds at the original 70/30 split. Broad is then 63% of the total account and Focus 27%. AAA becomes 38.7% of the whole account, calculated as 0.63 × 0.40 plus 0.27 × 0.50.

AAA is still 43% of the invested fund portion. Both descriptions are valid if their denominators are stated. Cash does not change the two funds’ pairwise overlap; it changes the investor’s total account exposure. Keep reserved cash and the invested portion separate if they serve different financial purposes.

Check the inputs before trusting the decimals

Use the overlap analyzer with the dated holdings you can verify. Match companies using a stable identifier where available, and investigate whether share classes or renamed securities have been treated as separate names. Do not casually combine economically different instruments because their labels look similar.

A holding list can also contain cash, derivatives, short positions or values that do not fit a simple long only equity calculation. This example assumes positive weights and no leverage. It does not measure factor exposure, credit risk, currency sensitivity or the possibility that different companies react to the same economic shock.

Turn the exposure into a research question

If one company dominates the combined portfolio, ask what would happen to the account under an explicitly hypothetical fall in that company while other holdings are unchanged. A 20% fall in a 43% position would mechanically reduce total portfolio value by 8.6% in that isolated scenario. It is not a forecast, and it ignores correlated moves elsewhere.

Continue with how to compare index funds and the rebalancing guide. The useful output is an understandable map of what the account owns. A count of fund names or one overlap score cannot substitute for that map.