13 Nov 2026
ETF Portfolio Overlap: How Do You Check What Your Funds Have in Common?
ETF portfolio overlap is the degree to which two or more funds hold the same securities. Because many ETFs draw from the same pool of large companies, an investor can own several funds with different names and still be concentrated in the same stocks. Checking overlap, measured by weight rather than by a simple count of shared names, shows how much distinct exposure each fund adds and whether a portfolio is as diversified as it appears.
Why does overlap happen?
Overlap is common for structural reasons. Broad U.S. equity indexes, growth funds, technology funds, dividend funds and many thematic funds all draw from the same universe of publicly traded companies. Market-capitalization weighting gives the biggest companies the biggest positions in most index funds, so those companies appear prominently across many products.
Concentration in the broad market has increased the effect. The top 10 stocks reached a record 40.7% of the S&P 500’s weight in 2025, according to RBC Wealth Management, compared with roughly 18% to 23% between 1990 and 2015.1 When a handful of companies make up a large share of the main index, they also tend to appear near the top of many other funds.
How is overlap measured?
There are two common ways to describe overlap.
By count. The number of securities two funds share, sometimes expressed as a percentage of each fund’s holdings. A count can give the wrong impression, because it treats a 0.1% position the same as a 7% position.
By weight. For each security held by both funds, take the smaller of its two weights, and add those amounts together. The result shows how much of one portfolio is effectively duplicated in the other. For example, if a stock is 6% of one fund and 4% of another, it contributes 4% to the weighted overlap. Weighted overlap is generally more informative, because it reflects how much money is actually duplicated.
Overlap can also be measured at the level of sectors, countries or factors such as growth and value, which can reveal similarities even when individual holdings differ.
How can investors check overlap?
Review each fund’s holdings. Most ETFs publish their complete holdings every business day on their websites, as required for funds relying on the SEC’s ETF rule.2 Downloading holdings for two funds and comparing weights is the most direct approach.
Use an overlap tool. Many brokerage and research platforms offer tools that calculate weighted overlap between funds automatically.
Look through to the whole portfolio. For investors holding several funds, a portfolio analysis tool can combine all holdings and show total exposure to each company, sector and country, which reveals overlap across the entire portfolio rather than between pairs.
Check the top holdings first. A quick comparison of each fund’s top 10 positions often reveals most of the meaningful overlap, because those positions carry the most weight.
How often should overlap be checked?
Overlap changes over time, even if an investor makes no trades. Index reconstitutions add and remove companies, market movements shift weights, and active managers change holdings. A fund that overlapped modestly with a core holding a few years ago may overlap substantially today if the same companies have grown to dominate both. Many investors review overlap at least once a year, often alongside rebalancing, and whenever they consider adding a new fund. Reviewing overlap before a purchase is particularly useful, because it shows whether the new fund adds the intended exposure or mainly reinforces positions already held.
How should the results be interpreted?
Overlap is not inherently good or bad. What matters is whether it matches the investor’s intent.
High overlap between a core fund and a satellite fund may mean the satellite fund adds little distinct exposure and instead increases concentration in companies already held. Our article on core and satellite investing explains how these roles work.
High overlap between two funds in the same role, such as two broad U.S. equity funds, may indicate redundancy, with two expense ratios paying for similar exposure.
Low overlap suggests each fund contributes something different, though investors should still check sector and factor exposure, because different holdings can still behave similarly.
Intentional overlap can be appropriate. An investor who wants extra weight in a sector or theme may deliberately hold a fund that overlaps with a broad index.
What are common overlap patterns?
Broad index and growth funds. Large-cap growth funds often hold many of the same top companies that dominate broad market indexes.
Technology and thematic funds. Funds focused on technology, AI, semiconductors or innovation frequently share large technology holdings. Our article on what an AI ETF is discusses this.
Dividend funds and value funds. Dividend-focused and value-focused funds often overlap in financials, energy, utilities and consumer staples. Our article on dividend ETFs explains dividend screens.
Option income funds and their underlying indexes. A covered call fund built on a broad index holds the same stocks as that index, even though its return pattern differs. Our article on covered call ETFs explains the strategy.
What can investors do about unwanted overlap?
Options include consolidating redundant funds, replacing a fund with one that has a different methodology, such as equal weighting, or choosing satellite funds selected specifically for their distinct holdings. Our article on equal-weight versus market-cap-weight ETFs explains how weighting changes a portfolio. Any change in a taxable account may have tax consequences, so investors should consider the cost of selling before restructuring. Our article on concentration risk in ETFs covers related measures, and more introductory topics are covered in our ETF basics guide.
Investments involve risk, including possible loss of principal.
Frequently asked questions
What is a good overlap percentage between two ETFs?
There is no universal threshold. Some investors view weighted overlap above roughly half as a sign that two funds provide similar exposure, but the right level depends on purpose. Two funds intended to play the same role can reasonably overlap; a fund meant to diversify a core holding generally adds more when overlap is low.
Why is weighted overlap more useful than counting shared stocks?
Counting treats every shared stock equally, even if one is a tiny position. Weighted overlap reflects how much money is actually duplicated by adding the smaller weight of each shared holding. It shows whether the overlap is in small positions or in the holdings that drive most of each fund’s results.
Where can I find an ETF’s holdings?
Most ETFs publish full holdings on their websites every business day. Brokerage platforms and research sites also display holdings, though some update less frequently. The fund’s own website is usually the most current source. Fact sheets, usually updated monthly or quarterly, summarize top holdings and sector weights.
Can two ETFs with different holdings still behave alike?
Yes. Funds can hold different companies but share similar sector weights, factor tilts or sensitivity to interest rates and economic conditions. Comparing sector and factor exposure, not just individual holdings, gives a fuller picture of how similar two funds are.
Does overlap matter for bond ETFs?
It can. Bond funds may hold the same issuers or similar maturities and credit qualities, which can concentrate exposure to particular companies, sectors or interest rate movements. Comparing issuer, sector, duration and credit quality helps identify overlap in fixed income portfolios.
- RBC Wealth Management, “The ‘Great Narrowing’: S&P 500 concentration” (2026).
- U.S. Securities and Exchange Commission, Rule 6c-11 under the Investment Company Act of 1940, portfolio holdings disclosure requirements.
Cite this page: Adam Patti, "ETF Portfolio Overlap: How Do You Check What Your Funds Have in Common?," VistaShares, updated November 13, 2026, https://www.vistashares.com/etf-portfolio-overlap/. Plain-text version.
This material is provided for educational purposes only. It is not investment, legal or tax advice, and it is not a recommendation or an offer to buy or sell any security. Information is drawn from sources believed to be reliable as of the date of publication, is not guaranteed as to accuracy or completeness, and may change without notice. Figures attributed to third parties are their estimates. Projections and forecasts are not guarantees of future results. Investors should consult their own financial, legal and tax professionals before making investment decisions. Investments involve risk, including possible loss of principal. ETF shares are bought and sold at market price, which may differ from net asset value, and brokerage commissions and other trading costs may apply.