ETF portfolio checkup
Different fund names can hold the same stocks.
Use holdings, costs and matching performance periods to understand what each fund adds. A higher fund count does not tell you how different the underlying exposures are.
Collect the fund documents first.
For each exact fund and share class, collect its prospectus, strategy description, expense information, holdings file and the date of those holdings. Write down the index or mandate it follows. Similar ticker names do not establish identical exposure.
Review fees in the fund’s prospectus and compare the same fee definitions. Also check trading costs with your broker; an expense ratio does not describe every cost of buying and selling. Investor.gov explains fund fees and expenses.
Run a portfolio checkup.
Give each fund a job
Write what the fund is meant to contribute: broad equity exposure, a region, an industry, income or another defined role. Then compare that intent with its actual mandate and holdings.
Prepare comparable holdings
Use matching snapshot dates when possible. Match securities with stable IDs and consistent sector and country labels. A top-ten-only file is a partial view, so keep its coverage visible. The overlap tool requires the CSV columns explained in the data guide.
Inspect overlap and allocations
Run the overlap analysis, then enter your fund allocations if you want combined exposure. Blank allocations use equal weights as an illustration. Look at both the shared holdings and the concentration in your largest combined positions.
Compare a common history
Use the $10,000 comparison with a common currency, matching dates and consistent adjustment methods. A total-return series includes distributions according to its source; a price series can exclude them. The tool does not add dividends when you change the data-basis selector.
Record a conclusion to investigate
State whether the funds appear to duplicate a role, provide different exposures, or need better data. Overlap alone does not tell you which fund to buy or sell. Consider costs, your objectives and any consequences before changing a portfolio.
A worked overlap example
Fictional funds: Fund A holds 60% Alpha and 40% Beta. Fund B holds 20% Alpha and 80% Gamma. All holdings are included, and the dates match.
| Question | Calculation | Result |
|---|---|---|
| How much weight overlaps? | Minimum weight in shared Alpha: min(60%, 20%) | 20% overlap |
| How many holdings are shared? | Alpha is one of two holdings in each fund | 50% of each fund’s holdings count |
| What if I allocate equally? | Alpha: 50% × 60% + 50% × 20% | 40% combined Alpha exposure |
The other combined positions are 20% Beta and 40% Gamma. A 20% pairwise overlap is not the same number as the 40% combined exposure to Alpha.
Check the fund, not just the return chart.
An ETF can trade above or below its net asset value. Its bid-ask spread can also add a trading cost. Review the issuer’s premium/discount history and the trading information relevant to the exact fund. These issues are explained in the SEC staff ETF bulletin.
Two charts can differ because of currencies, share classes, reinvestment assumptions, observation dates or adjustment methods. Explain those differences before treating a performance gap as evidence of a better strategy.
Your review checklist
These checkboxes are a reading aid; they are not saved or sent. Keep your notes in the Decision Journal. You can also print this guide from your browser.
StockMags educational guide · Updated October 4, 2026. Research tools do not determine whether an investment is suitable for you. Investments can lose value.
