Fund overlap: calculate indirect issuer exposure
Fund overlap asks how much of a portfolio reaches the same underlying issuer through different holdings. Count the economic routes, not just ticker names. A direct share position and two fund positions can create one shared company exposure even when each account line has a different symbol.
Distinguish the wrapper from its holdings
Investor.gov explains that ETFs pool investor money into a portfolio of securities or other assets. A fund share is the investor’s legal holding; look-through issuer exposure is a research reconstruction. It does not mean the investor directly owns or can vote every underlying security.
Begin with portfolio market-value weights at a stated common observation time. Obtain the fund’s actual holdings disclosure and date. A name suggesting “technology” does not establish which companies are held. Creation baskets, sample portfolios and complete holdings disclosures can have different roles, so verify the document before using its percentages.
Hypothetical issuer overlap
Assume a portfolio has 20% in Fund A, 15% in Fund B, 5% directly in Issuer Cedar and 60% elsewhere. Fund A has 8% of assets in Cedar; Fund B has 12%. Indirect exposure is 20% × 8% + 15% × 12% = 3.4% of the portfolio. Adding direct exposure produces 8.4%.
| Look-through worksheet | Portfolio weight | Cedar inside holding | Contribution |
|---|---|---|---|
| Fund A | 20% | 8% | 1.6% |
| Fund B | 15% | 12% | 1.8% |
| Direct Cedar shares | 5% | 100% | 5.0% |
| Total mapped Cedar exposure | 8.4% |
Do not add the full 35% fund allocation to the 8.4% issuer result. The former describes wrappers, while the latter replaces relevant parts of those wrappers with an underlying classification. Maintain separate tables for legal holdings and economic look-through so the total is not counted twice.
Preserve incomplete disclosure
Suppose Fund B’s disclosed list covers only 90% of its assets. Its unresolved contribution is 15% × 10% = 1.5% of the portfolio. Keep that amount unclassified rather than assuming it contains no Cedar. The calculated 8.4% is the mapped exposure under the available records, not necessarily the precise current total.
If one fund holds another fund, continue the path only where the next layer’s holdings are available. Multiply weights along each path and watch for circular fund structures. Record cash and other assets separately. A reconstruction intended for ordinary equity and cash holdings should not silently translate derivative notionals into comparable stock ownership.
Connect the result with operating questions
Once the issuer total is mapped, attach the same company operating event to all relevant routes. A factory disruption affecting Cedar is one underlying event, even if three portfolio lines reference it. The exposure table helps prioritize evidence checks; it does not measure price correlation or prescribe a position limit.
Recompute when fund disclosures or direct holdings change, preserving the observation dates. Price movement can alter fund weights without an underlying trade, so changes in weight alone do not prove a manager bought or sold. The finished output should report mapped issuer exposure, unresolved coverage and the oldest relevant holdings date.
FAQ
Is owning two funds evidence of diversification?
It establishes two legal holdings. Underlying issuer, sector and dependency overlap need their own evidence before drawing an economic-diversification conclusion.
Should cash inside funds be removed from the denominator?
Not for a whole-portfolio exposure map. Keep cash as a category; a stock-only rescaling answers a different question and needs a separate label.