Methodology · reviewed
Holdings overlap
Two funds with different names can own mostly the same companies. Overlap adds up, company by company, the smaller of the two funds’ weights.
The formula
overlap = Σ min(weight in fund A, weight in fund B)
Across issuer-published holdings. Identical portfolios score 100%; funds with nothing in common score 0%.
Worked example
If Apple is 5% of fund A and 3% of fund B, it adds 3%. Add that up across every shared company to get the total.
How it is done
Holdings come from the issuers’ own files: full lists for iShares, top-ten lists from Vanguard factsheets.
Companies are matched by a normalised name, resolved against a list of listed companies where possible, so the same company is counted once.
Where one fund publishes only its top ten, we also show the overlap as a share of what both disclose, which is the fairer comparison.
Limits to know about
- Holdings are published monthly or quarterly and can be weeks old.
- Top-ten lists understate overlap, because smaller shared positions are not visible.
Sources
- iShares holdings files
- Vanguard factsheets
Reviewed . If a figure on the site does not follow this method, tell us. This is information, not advice.