Frequently asked questions

Fund overlap is the percentage of two or more funds' portfolios invested in the same securities. If VTI and VOO both hold Apple at 5% weight, that position is "overlapping" — you're doubling your Apple exposure when you hold both funds.

High overlap isn't inherently bad, but it means your funds are not diversifying you as much as their different names suggest. A 75% weighted overlap between two funds means only 25% of one fund's weight is adding genuinely new exposure.

We use weighted overlap: for each security held by two or more funds, we take the minimum of each fund's weight in that security and sum those minimums. This gives the fraction of each fund's portfolio weight that is "already covered" by the other funds.

Example: if Fund A holds Apple at 7% and Fund B holds Apple at 4%, the overlap contribution from Apple is 4% (the minimum). If every holding in Fund A had a counterpart in Fund B at equal or greater weight, Fund A would show 100% overlap — meaning B already contains everything A offers.

The result is per-fund: because Fund A might be 80% in Fund B while Fund B is only 40% in Fund A (Fund B is the larger, more diversified fund). The comparison page shows both directions.

US-registered funds file quarterly holdings with the SEC on Form NPORT-P. The SEC makes these filings public 60 days after the end of the reporting quarter. This is a regulatory disclosure delay — not a limitation of OpenBell.

ETF issuers also publish daily holdings on their own websites, but we deliberately use only NPORT-P data so that every fund type — ETFs, mutual funds, and closed-end funds — is analyzed on the same data basis. Mixing daily ETF data with quarterly mutual fund data would make comparisons misleading.

Every comparison shows the exact as-of date and links directly to the SEC filing so you can judge how fresh the data is.

The most common reasons a fund isn't listed:

• It's a bond fund, money market fund, or ETN — these are excluded from v1.
• It was recently launched and hasn't filed a quarterly NPORT-P yet (new funds get 90 days to file their first report).
• It failed our data quality checks — for example, holdings weights don't sum to a reasonable range. These are flagged for review and may be re-added.
• It's a foreign-domiciled fund that doesn't file NPORT-P with the SEC.

Our universe covers approximately 11,000 US-registered funds. Bond fund overlap is planned for v2.

Yes. You can compare up to six funds at once. N-way comparisons show:

• Holdings shared by all selected funds
• Holdings shared by any subset of funds (tiered by how many funds hold them)
• Holdings unique to each individual fund
• A pairwise matrix showing every two-fund overlap at a glance

You can add funds using the comparison tool on the homepage, or by typing a URL directly: /overlap/VTI-vs-VOO-vs-SCHB.

All holdings data comes from Form NPORT-P, filed quarterly with the SEC by every US-registered investment company. OpenBell fetches these filings from SEC EDGAR, parses the XML, and links directly to the source filing on every comparison page so you can verify any figure.

Fund metadata (names, tickers, fund families) comes from the SEC's Investment Company Series and Class Information dataset. CUSIP-to-ticker mapping uses OpenFIGI (Bloomberg's identifier service).

See our data sources page for the complete picture.

Our data pipeline runs daily and picks up any new NPORT-P filings submitted to EDGAR in the previous 36 hours. The underlying fund data updates quarterly as each fund files. The "as of" date and "filed" date on each comparison show exactly when each fund's data was last updated.

Yes. All fund overlap analysis is free with no account required. Comparisons are shareable by URL. We may add optional features for signed-in users in the future (saved comparisons, alerts), but the core analysis will remain free and ungated.

No. OpenBell reports facts about portfolio composition. We do not offer investment advice, buy/sell recommendations, or opinions about whether any fund is a good investment. All data is sourced from public SEC filings and is provided for informational purposes only.