ETF Overlap: How to Spot Hidden Concentration

Owning several exchange-traded funds can make an investment portfolio look diversified. But different funds may own many of the same companies, leaving more money tied to a small group of businesses than you realise.

This is called ETF overlap. It is not automatically a problem, but it is worth understanding. Counting funds tells you how many investment products you own—not how widely your underlying investments are spread.

This guide explains how to check overlap and interpret it alongside your wider wealth. It is educational only, not personalised financial, investment, tax or legal advice. Investments can lose value. Consult a qualified professional for guidance on your own situation.

What ETF overlap actually means

ETF overlap happens when two or more funds contain some of the same underlying investments.

For example, a broad stock-market ETF and a technology-focused ETF may both own shares in the same large technology companies. Adding the second fund can increase your exposure to those businesses rather than introduce entirely new investments.

Overlap can also exist between an ETF and individual shares you own directly.

There are several layers to check:

• Shared holdings: The same companies or securities appear in multiple investments.
• Sector concentration: Different companies operate in the same industry.
• Geographic concentration: Investments are heavily connected to one country or region.
• Common risk factors: Holdings respond to similar pressures, such as interest-rate changes.

Funds do not need identical holdings to behave similarly. Equally, two funds sharing some holdings are not necessarily identical in their overall risk.

Start with holdings, not fund names

Fund names are useful labels, but they do not provide a complete picture of what you own.

Words such as “global,” “growth,” “dividend” or “innovation” describe an approach. They do not establish that a fund is different from everything else in your portfolio.

For each ETF, find information from its provider, such as:

• Its investment objective and benchmark, if applicable.
• Its latest available holdings and their weights.
• Its sector and geographic breakdowns.
• The date of the information.

Use full holdings lists where available. A top-ten list can reveal obvious concentration, but it cannot establish the full extent of overlap.

Try to compare information from similar dates. Holdings and weights change, so a comparison between an old report and a recent one may be misleading.

Some ETFs use derivatives or other structures to deliver their exposure. In those cases, the assets listed as holdings may not tell the whole story. Read the fund documentation to understand what exposure it is designed to provide.

Calculate your exposure to a shared holding

The most useful question is often not “How many companies do these funds share?” but “How much of my money is exposed to this company?”

Use this calculation:

Exposure through one ETF = amount invested in the ETF × the company’s weight in that ETF

Consider a hypothetical portfolio, expressed in currency units:

| Investment | Position value | Weight of Company A | Exposure to Company A | |---|---:|---:|---:| | Broad-market ETF | 6,000 | 5% | 300 | | Sector ETF | 2,000 | 15% | 300 | | Company A shares | 500 | 100% | 500 | | Total | 8,500 | — | 1,100 |

Company A represents approximately 12.9% of this investment portfolio: 1,100 divided by 8,500.

These figures are illustrative, not actual fund holdings or recommended allocations. They show why checking each account or fund separately can miss your combined exposure.

Use values expressed in the same currency, and make sure the portfolio total includes everything you intend to measure.

Distinguish overlap from portfolio concentration

A common way to compare two funds is to add the smaller holding weight for every security they share.

Suppose Company A makes up 5% of one fund and 15% of another. It contributes five percentage points to this overlap measure. Repeat that calculation for all shared securities to estimate their weighted overlap.

This is different from simply counting shared names. Two funds could share many small positions while having quite different largest holdings.

However, pairwise overlap is not the same as your personal portfolio concentration. It does not account for how much money you have invested in each fund.

A heavily overlapping fund that represents a small slice of your portfolio may have less influence than a less-overlapping fund that holds most of your investment money. For a practical review, calculate your combined exposures as well as any overlap percentage.

Look beyond identical company names

After checking shared holdings, review broader sources of concentration.

Sector exposure: Several funds may own different companies but still depend heavily on one industry. A long list of holdings does not eliminate risks common to that industry.

Geographic exposure: Different funds may focus on the same market. Also, a company’s listing location does not necessarily show where it earns its revenue.

Currency exposure: The currency used to trade an ETF is not necessarily the currency exposure of its investments. Currency-hedged share classes add another distinction, so check the documentation rather than relying on the ticker’s trading currency.

Bond exposure: Bond funds may share issuers or have similar sensitivity to interest rates and credit conditions. Different maturity dates do not automatically make two bonds independent sources of risk.

There is no universal overlap percentage that makes a portfolio appropriate or inappropriate. Its significance depends on the fund weights, underlying exposures and purpose of the portfolio.

Put investment concentration in a wider wealth picture

An investment portfolio is only one part of personal wealth. Cash, bonds, precious metals and other assets provide additional context, alongside liabilities.

Keep the denominator clear. “Company A is 12.9% of my investment portfolio” means something different from “Company A is 12.9% of my total assets.” Neither figure should be labelled as the other.

Net worth can be a confusing denominator for concentration because debts reduce it. For this particular exercise, investment-portfolio value or total assets may give a clearer picture, provided you label the measure consistently.

Also consider connections outside your investments. If someone’s employment income and a large share of their investments depend on the same industry, their financial exposure may be broader than the investment figures alone suggest.

Build a repeatable review

A simple spreadsheet can make the process manageable:

1. List each fund and direct investment with its current value.
2. Record the date and source of each holdings report.
3. Calculate combined exposure to major shared holdings.
4. Summarise sector, geographic and other important concentrations.
5. Note incomplete data or exposures you do not fully understand.

Repeat the check at a regular review point or when considering a change. Discovering overlap is information, not an automatic instruction to transact. Any decision may involve costs, tax consequences and personal circumstances that deserve separate consideration.

Track it in one place

Ledgerol is a net worth tracking app for bank accounts, cash, stocks and ETFs, bonds, precious metals, commodities and crypto. Tracking asset values together can provide context for your separate overlap review. Keep the underlying holdings analysis alongside that overview so you can distinguish how much wealth you have from where your investment risks are concentrated.