ETF Overlap
Calculator

What is ETF overlap and why does it matter?

ETF overlap occurs when two or more ETFs hold the same underlying stocks. Australian investors often hold multiple ETFs like VAS, VGS, and NDQ without realising they share large positions in the same US mega-cap tech companies.

Three ways to measure overlap

This calculator shows overlap three ways. The Holdings tab shows stock-level overlap using the minimum weight method. The Country tab shows how much of each ETF is allocated to the same countries — useful for spotting unintended US concentration. The Sector tab shows GICS sector breakdowns side-by-side so you can see if you're doubling up on Information Technology across multiple funds.

Common high-overlap pairs on the ASX

VGS and IVV typically show 60–70% holdings overlap because both are dominated by US large caps. NDQ and IVV overlap around 55–65% due to heavy Nasdaq weighting in the S&P 500. VAS and A200 share nearly 95% of holdings, making them near-identical. From a country perspective, VGS and NDQ both have 70%+ US allocation — even if the specific stocks differ, the country concentration compounds.

What overlap is acceptable?

There is no universal rule, but as a guide: below 20% is low and generally fine for diversification; 20–40% is moderate and worth monitoring; above 40% suggests significant duplication that may not be intentional.

The VAS + A200 + STW problem

The most common overlap scenario among Australian retail investors is holding two or more Australian equity ETFs simultaneously. VAS (Vanguard Australian Shares), A200 (Betashares Australia 200), and STW (SPDR S&P/ASX 200) all track essentially the same index — the top 200 or 300 Australian listed companies. Holding all three does not increase diversification; it replicates the same concentrated exposure to BHP, CBA, CSL, NAB, and ANZ (which together represent approximately 35% of the ASX 200 index) at a higher total cost. The correct approach is to pick one Australian equity ETF and pair it with genuinely different asset classes — international equities, fixed income, or property.

When overlap is acceptable

Some portfolio constructions intentionally use overlapping ETFs for a purpose. A core/satellite approach might hold VGS (global equities) as the core, then add NDQ (Nasdaq 100) as a satellite overweight to US technology — knowing that NDQ overlaps significantly with VGS's US holdings. This is a deliberate tilt, not an accidental duplication. The distinction matters: intentional overlap reflects a view about which exposures to overweight; accidental overlap means you're paying two sets of management fees for the same risk. This tool helps distinguish between the two by quantifying exactly how much of your combined portfolio is concentrated in each position.