What is ETF Overlap? Why It Matters and How to Check It

What is ETF Overlap?

ETF overlap is when two or more ETFs in your portfolio hold the same underlying stocks or bonds. The more overlap, the less diversification you actually have.

Example: If you own both VTI (Total Stock Market) and VOO (S&P 500), roughly 85% of VTI's value is in the same 500 companies that VOO holds. You think you have two different investments, but you're mostly owning the same stocks twice.

Check any two ETFs: Free ETF Overlap Tool

Why Should You Care?

1. False Diversification

Many investors own 4-5 ETFs thinking they're diversified:

Portfolio	Looks Like	Actually
VOO + VTI	2 funds, 4,000 stocks	85% identical
QQQ + VGT	2 tech funds	48% identical
SPY + IVV	2 funds	99.9% identical
SCHD + VYM	2 dividend funds	38% identical

The person holding VOO + VTI thinks they own 4,000+ unique stocks. In reality, over 85% of their money is in the same 500 companies.

2. Concentrated Risk

High overlap means concentrated risk. If the S&P 500 drops 30%, both VOO and VTI drop nearly the same amount — your "diversification" didn't protect you.

Real diversification requires ETFs that hold different types of assets:

• U.S. stocks + International stocks (low overlap)
• Stocks + Bonds (zero overlap)
• Large cap + Small cap only (moderate overlap)

3. Tax Inefficiency

Owning overlapping ETFs in taxable accounts creates problems:

• Same stock pays dividends through multiple ETFs
• Can't efficiently tax-loss harvest between substantially identical funds
• More complicated tax reporting for minimal benefit

How to Measure ETF Overlap

ETF overlap is calculated by comparing the holdings of two ETFs:

Overlap Percentage = Weight of shared holdings in both ETFs

There are different ways to calculate this:

Method 1: Count-Based Overlap

Simply count how many stocks appear in both ETFs divided by total unique stocks.

Example: VOO has 503 stocks, VTI has 3,800 stocks, 503 are shared = 503/3,800 = 13% overlap

This is misleading because it doesn't account for how much money is in each stock.

Method 2: Weight-Based Overlap (Better)

Compare the dollar weight of each shared stock in both ETFs, taking the minimum weight.

Example: If Apple is 7.1% of VOO and 5.8% of VTI, the overlap contribution is min(7.1%, 5.8%) = 5.8%

This is what EigenDex uses — it gives you a more accurate picture of how much of your money is actually duplicated.

Try it with your ETFs →

Common Overlap Scenarios

Very High Overlap (80%+) — Redundant

Pair	Overlap	Verdict
SPY vs VOO	99.9%	Completely redundant
VOO vs IVV	99.9%	Completely redundant
VTI vs VOO	~85%	Mostly redundant
ITOT vs VTI	~99%	Completely redundant

Action: Pick one and sell the other (in tax-advantaged accounts) or stop buying the duplicate.

Moderate Overlap (30-60%) — Evaluate

Pair	Overlap	Verdict
QQQ vs VGT	~48%	Some benefit, but heavy tech
SCHD vs VYM	~38%	Reasonable diversification
VOO vs QQQ	~42%	Tilting toward tech

Action: This can be fine if intentional. Just understand you're making a concentrated bet on the overlapping sectors.

Low Overlap (0-20%) — Good Diversification

Pair	Overlap	Verdict
VOO vs VXUS	~0%	Excellent (US + International)
VTI vs BND	0%	Perfect (Stocks + Bonds)
VTI vs VNQ	~4%	Good (Broad + REIT tilt)
VOO vs VWO	0%	Excellent (US + Emerging)

Action: This is real diversification. Each fund serves a different purpose.

How to Fix Overlap in Your Portfolio

Step 1: Check Your Current Overlap

Use EigenDex to compare any two ETFs in your portfolio. Check every pair.

Step 2: Identify Redundant Positions

If two ETFs have 80%+ overlap, you're paying for the same stocks twice. Common redundancies:

• SPY + VOO (same thing)
• VOO + VTI (mostly the same)
• QQQ + multiple tech-heavy funds

Step 3: Consolidate or Diversify

Option A - Consolidate: Replace overlapping funds with one fund

• VOO + VTI → Just hold VTI (it includes everything in VOO)
• QQQ + VGT → Pick one tech-focused fund

Option B - Diversify: Replace one overlapping fund with something different

• VOO + VTI → VOO + VXUS (US + International)
• Two tech funds → One tech fund + One value fund

Step 4: Consider Tax Implications

In taxable accounts: Don't sell everything at once. Stop buying the duplicate and let it be, or harvest losses if available.

In IRAs/401(k)s: Swap freely — no tax consequences for selling and rebuying.

The "Lazy" Portfolios with Zero Overlap

These simple portfolios maximize diversification with minimal overlap:

Two-Fund Portfolio

ETF	Allocation	Role
VTI	80%	All US stocks
VXUS	20%	All International stocks
Overlap	0%

Three-Fund Portfolio

ETF	Allocation	Role
VTI	60%	All US stocks
VXUS	20%	All International stocks
BND	20%	All US bonds
Overlap	0%

Four-Fund Portfolio

ETF	Allocation	Role
VTI	50%	All US stocks
VXUS	20%	All International stocks
BND	20%	All US bonds
BNDX	10%	International bonds
Overlap	0%

Common Mistakes

Mistake 1: Collecting ETFs

"I own 12 ETFs so I'm well diversified." — No, if 8 of them overlap heavily, you effectively own 4 funds with extra complexity.

Mistake 2: VOO + VTI + SPY

This is the most common mistake. All three hold the S&P 500. VOO vs VTI has ~85% overlap. SPY vs VOO is 99.9%. See the data.

Mistake 3: Ignoring Bond Overlap

AGG vs BND has 90%+ overlap. Don't own both. Read our AGG vs BND comparison.

Mistake 4: Same Theme, Different Wrappers

SCHG + VUG + IWF are all "large-cap growth" — they overlap 70-90%. Pick one.

Tools to Check ETF Overlap

1. EigenDex (that's us!) — Free, instant overlap analysis for 248+ ETFs with Venn diagrams and shared holdings tables
2. ETF Research Center — Another overlap tool with different methodology
3. Morningstar X-Ray — Portfolio-level analysis (requires premium for full features)

Key Takeaways

1. ETF overlap = hidden duplication in your portfolio
2. Weight-based overlap is more accurate than simple stock count
3. 80%+ overlap means those ETFs are redundant — consolidate
4. 30-60% overlap is okay if the concentration is intentional
5. Real diversification comes from different asset classes, not more ETFs
6. Check before you buy — use EigenDex's free comparison tool

The goal isn't zero overlap everywhere — it's intentional portfolio construction where you understand exactly what you own and why.

Check your portfolio overlap now →