✦ What the ETF overlap checker does
- Finds repeated holdings represented in the available fund dataset
- Shows your effective % allocation to each security after overlap
- Flags when repeated holdings create concentrated effective exposure
- Detects sector over-concentration caused by overlapping funds
- Works across all connected brokerage accounts simultaneously
Why ETF Overlap Is the Most Common Diversification Mistake
The rise of index investing has created a new and largely invisible problem: most broad market, large-cap growth, and sector ETFs share the same top holdings. Apple is the number-one holding in VOO, QQQ, VGT, XLK, and dozens of other popular ETFs. If you own three of these simultaneously, you don't have diversification across three funds — you have a significant overweight in Apple, Microsoft, Nvidia, and a handful of other mega-cap technology names, replicated through three different wrappers. The fund names look different. The underlying exposure is nearly identical.
The 2022 tech selloff exposed this risk in a way that surprised a large number of self-directed investors. People who believed they held a diversified collection of ETFs — a broad market fund, a growth fund, a tech sector fund — found themselves losing in lockstep because all three were effectively holding the same assets. There was no cushion between the positions because there was no genuine independence between them. The overlap made the "diversification" conceptual rather than real.
Overlap doesn't just matter for diversification — it affects how you respond in a drawdown. You can't rebalance out of a position you didn't know you had. If you think your Apple weight is 5% because that's what VOO shows you, but your true effective Apple weight across all funds is 14%, your rebalancing decisions are being made on incorrect data. Every calculation that follows from an incorrect position size — risk allocation, stop-loss placement, portfolio beta — will also be wrong. Overlap analysis is not optional for serious portfolio management.
The Most Common ETF Overlaps
These observed examples use every reported non-cash holding in the licensed dataset. The percentage is the sum of the smaller normalized weight for each security held by both funds. It is a duplication measure, not a universal portfolio recommendation.
| ETF Pair | Weight overlap | Shared securities | Tool band | Largest shared positions | Try it |
|---|---|---|---|---|---|
| VGT + XLK | 79.0% | 72 | Severe | NVDA, AAPL, MSFT, AVGO, MU | Check |
| QQQ + VUG | 58.7% | 57 | Severe | NVDA, AAPL, MSFT, AMZN, GOOGL | Check |
| QQQ + IWF | 58.2% | 61 | Severe | NVDA, AAPL, MSFT, MU, GOOGL | Check |
| QQQ + VOO | 53.6% | 87 | Severe | NVDA, AAPL, MSFT, AMZN, GOOGL | Check |
| SPY + VOO | 96.2% | 489 | Severe | NVDA, AAPL, MSFT, AMZN, GOOGL | Check |
| QQQ + VGT | 52.3% | 38 | Severe | NVDA, AAPL, MSFT, MU, AMD | Check |
| VTI + VOO | 88.5% | 502 | Severe | NVDA, AAPL, MSFT, AMZN, GOOGL | Check |
| VTI + QQQ | 47.6% | 92 | Severe | NVDA, AAPL, MSFT, AMZN, GOOGL | Check |
| VGT + VOO | 36.6% | 74 | Severe | NVDA, AAPL, MSFT, AVGO, MU | Check |
| VYM + SCHD | 21.4% | 78 | High | UNH, CVX, KO, PG, HD | Check |
| SCHD + VOO | 8.0% | 46 | Low | UNH, CVX, KO, PG, HD | Check |
| IWM + QQQ | 0.0% | 0 | Low | No shared securities | Check |
Financial Modeling Prep is the holdings provider. Fund dates range from 2026-08-18 to 2026-08-22. Every fund passed the publication checks for at least 20 holdings, 95% to 105% provider weight, and at least 97% retained coverage. Holdings are normalized to 100% before comparison. Content hash: 5fd8a50b63709137d9404350488c82c8b4582f9c4647c83cccdf11538cf7f0a9.
Holdings change, identifiers can differ across providers, and overlap does not measure return correlation, taxes, or future diversification. See the full QQQ vs VOO, SPY vs VOO, VTI vs VOO, and VGT vs VOO breakdowns.
What Overlap Does to Your Real Exposure
ETF overlap doesn't just affect your diversification score on paper. It has concrete consequences for how your portfolio behaves in real market conditions — and for your ability to manage it effectively.
Mega-cap concentration
When VOO + QQQ + VGT all hold Apple, your true Apple weight is 3–5× what any single fund shows. A single company's earnings, legal challenges, or product cycle becomes a significant driver of your overall portfolio performance.
Hidden drawdown risk
In a selloff that targets your most-overlapped holdings, you have much more at stake than your fund names suggest. The losses compound across funds rather than being offset by genuine diversification elsewhere in the portfolio.
Rebalancing blind spots
You can't rebalance a position you don't know you have. Overlap makes effective position sizing impossible without overlap analysis — and every rebalancing decision made on incomplete data compounds the problem over time.
Sector over-weighting
Three funds that each have 25% technology weighting don't give you a 25% tech portfolio — depending on how the overlap compounds, your effective tech exposure may be substantially higher than any single fund's stated allocation.
Cost of duplication
Owning the same holding across three ETFs doesn't reduce risk — it just adds management fees without adding diversification benefit. You pay three expense ratios for what is effectively one concentrated position.
International fund illusions
Many "international" ETFs have heavy exposure to US-listed multinationals or companies with predominantly US revenue. True geographic diversification requires looking at actual revenue and operational exposure, not just where a company is listed.
How Guardfolio's ETF Overlap Checker Works
Connect your brokerage accounts via read-only API — Guardfolio supports the major US and international brokers. Once connected, Guardfolio automatically ingests all of your fund holdings and disaggregates them to the underlying security level. Rather than showing you "VOO: 40% of portfolio," it shows you the effective weight of every stock and bond you actually own across all ETFs, weighted by your fund allocation sizes.
Guardfolio then identifies every security that appears in more than one of your ETFs, calculates your true effective position size in each one, and flags cases where overlap has created meaningful concentration. You see your actual top holdings — not the top holdings of your individual funds in isolation, but the true combined view. You also see your real sector weights, your real geographic exposure, and any individual security where overlap has pushed your weight above your defined threshold.
This isn't a manual lookup tool that requires you to enter two ticker symbols and get a static number. After you connect accounts, Guardfolio recalculates overlap whenever your holdings change from a sync or a manual update, so the picture stays current without re-running a two-ETF lookup by hand.
Connect once
Link your broker in minutes. Holdings update automatically as funds rebalance or you add positions — no manual data entry, no spreadsheet to maintain.
See all underlying holdings
Guardfolio breaks every ETF down to its constituent securities and weights your true exposure across all funds, giving you the complete picture of what you actually own.
Get alerted when overlap increases
When fund rebalancing increases your overlap above your threshold, you're notified before it becomes a problem — via email or Telegram, whichever you prefer.
How to Reduce ETF Overlap in Your Portfolio
Once you've identified overlap, here are five practical steps to fix it without triggering unnecessary tax events or abandoning your investment strategy.
1. Replace redundant funds with non-overlapping alternatives
If VOO and QQQ are your two largest positions, consider replacing QQQ with an ETF that targets a genuinely different market segment — small-cap value (VBR), international developed (VEA), or emerging markets (VWO). The goal isn't fewer ETFs, it's fewer duplicated exposures.
2. Use total-market funds as your core, not multiple index funds
Holding VTI + VOO + SPY is three wrappers around the same stocks. A single total-market fund (VTI or ITOT) gives you the broadest exposure with zero overlap. Add satellite positions in genuinely distinct asset classes. See the SPY vs VOO breakdown for why two S&P 500 wrappers are pure duplication.
3. Check sector-level overlap, not just holdings
Two ETFs can have zero holdings overlap yet both be 30% technology. Sector overlap is harder to spot but equally dangerous. Use Guardfolio's sector analysis to see your true sector weights across all funds combined.
4. Tax-loss harvest to restructure
If selling an overlapping fund triggers capital gains, wait for a drawdown and harvest losses to restructure tax-efficiently. You can replace a highly-overlapping fund with a similar but non-identical alternative (mind the wash-sale rule) to reduce overlap without a tax hit.
5. Set up ongoing overlap monitoring
Fund compositions change quarterly as they rebalance. An overlap problem you fix today can re-emerge in 6 months. Guardfolio's continuous monitoring recalculates overlap automatically and alerts you when it increases above your threshold.
Explore Related Features
Further reading
- Portfolio diversification guide — why overlap weakens diversification
- Concentration risk explained — when overlap becomes dangerous
- QQQ vs VOO overlap - a concrete example of repeated mega-cap exposure
- UCITS ETF overlap hub - VWCE, IWDA and European fund pairs
- Portfolio tracker UK - ISA, SIPP and multi-broker monitoring
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