How we compute it.
Every figure on etf.money is computed from real, published fund holdings — not editorial guesswork. Here is exactly how, where the data comes from, and what the numbers do and don't mean.
Pairwise overlap
Overlap % is the sum, over every security held by both funds, of the smaller of the two weights:
overlap = Σ min( weight in A, weight in B )This is the standard ETF-overlap definition and it is symmetric. The two coverage figures answer a different question — “how much of one fund already lives inside the other” — which is why they're rarely equal.
Portfolio redundancy & concentration
For a whole portfolio, each fund is normalized to its equity sleeve and scaled by your allocation, then every underlying security is aggregated across your funds. Redundancy is the portfolio weight that shows up in more than one fund:
redundancy = Σ ( total weight − largest single-fund weight )It is 0% when your funds share nothing and rises as they hold the same securities — two identical funds at 50/50 are 50% redundant. Concentration is your single largest holding once every fund is looked through and aggregated: a stock can be a small line in several funds yet add up to a large share of the whole portfolio.
What counts toward a figure
- Equity sleeve only. Weights are normalized to each fund's investable securities, so cash, money-market, FX, futures and other derivative lines don't deflate or inflate the result.
- Asset class matters. A company's equity and its bonds share a ticker but are different exposures — we keep them apart so they never match spuriously.
- Duplicate lines are summed. Where a fund lists the same security across several lines (e.g. multiple bonds from one issuer), they're aggregated before matching.
Where the data comes from
Figures derive from issuers' own public, regulatory holdings disclosures — UCITS funds publish their holdings. We publish a fund's actual portfolio, never an index constituent list. Every fund carries an “as of” date so you always know how current a figure is.
Limitations & honesty
- Cross-issuer matching keys on ticker today. Within one issuer this is exact; across issuers (e.g. an iShares vs. a Vanguard fund) we match on ticker, which is close but not perfect. FIGI-level precision — which lifts same-index pairs toward their true ~100% — is on the roadmap.
- Synthetic (swap-based) ETFs. These hold a swap plus a collateral basket rather than the index constituents, so their disclosed holdings aren't directly comparable. We flag replication and treat these carefully.
- This is information, not investment advice.
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