About OverlapCheck

OverlapCheck is an independent tool for long-term investors who hold several ETFs across several accounts. It answers one question well: what do your funds actually own, combined — and what changes underneath over time. It is informational and does not recommend trades.

Who it's for

People who buy and hold index funds, contribute regularly, and have no single screen that shows their whole portfolio's underlying exposure. The free tools do the look-through and overlap arithmetic. The free holdings watch adds a complete holdings-based review, every qualifying what-if scenario, and a saved dated baseline. It then runs 12 monthly holdings checks, with human review when a material change is detected. Neither requires connecting a brokerage account; you enter funds and amounts yourself.

Where the data comes from

Fund holdings come from official issuer files and SEC filings — no third-party estimates. Every data page shows the applicable source date; different issuers publish on different schedules, so two funds can carry dates a few days apart, which can shift a combined weight slightly. The formulas and known limitations are documented in our methodology. The site also hosts a set of derived options dashboards built from end-of-day open interest; they are secondary to the portfolio tools.

Who runs it

OverlapCheck is an independent tool, not affiliated with any fund issuer, broker, or data vendor. It sells no advertising and takes no referral fees from issuers. We publish the method rather than credentials: every number on the site can be reproduced from the public filings we cite, and we'd rather you check the arithmetic than trust a byline.

How the analysis is produced

Pairwise overlap is calculated by matching shared securities and summing the smaller portfolio weight for each match. Portfolio look-through multiplies each fund holding by the amount allocated to that fund, then combines identical securities. The formulas, limitations, and sector-classification rules are documented in our methodology.

Editorial standards

We distinguish measured data from interpretation, show dates next to time-sensitive figures, and avoid presenting max pain or gamma exposure as predictions. When a source is delayed or a method has a known limitation, the relevant page says so. Material template and guide changes use a fixed, reviewable update date rather than changing on every build.

Scope and corrections

Coverage currently focuses on selected US-listed ETFs, a set of European UCITS funds, and some liquid US options products. OverlapCheck is not a broker, adviser, tax professional, or substitute for issuer records. If a displayed figure disagrees with an issuer file, verify the issuer record before acting and send the affected URL to info@overlapcheck.com.