Quick Comparison
| Feature | VTI | VOO |
|---|---|---|
| Index | Total U.S. Market | S&P 500 |
| Holdings | ~3,700 | ~500 |
| Holdings Overlap | ~86–90% | |
| Expense Ratio | 0.03% | 0.03% |
| Market Cap Exposure | Large + Mid + Small | Large Cap Only |
How Much Do VTI and VOO Overlap?
The overlap between VTI and VOO is extremely high because VTI already contains almost every stock inside VOO. VOO tracks the S&P 500 — the 500 largest U.S. companies. VTI tracks the entire U.S. stock market, which includes those same 500 companies plus thousands of mid- and small-cap stocks.
Since large-cap companies dominate market capitalization, they make up the majority of VTI's weight. That means most of VTI's portfolio mirrors VOO's top holdings.
Key insight: VTI holds ~3,700 stocks vs VOO's ~500, but because large caps account for 80%+ of total market weight, the practical overlap is 86–90%. The extra diversification from mid- and small-caps has a smaller impact than the numbers suggest.
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Diversification Differences
VOO provides exposure to large-cap U.S. companies only. It excludes mid-cap and small-cap stocks entirely.
VTI, on the other hand, includes large-cap stocks (same as VOO), mid-cap stocks, and small-cap stocks. However, because large-cap stocks account for roughly 80%+ of total U.S. market capitalization, the diversification difference between VTI and VOO is smaller than it appears.
Performance Comparison
Historically, VTI and VOO have delivered nearly identical long-term returns. Small differences occur when small-cap stocks outperform or underperform large caps.
In strong small-cap cycles, VTI may slightly outperform VOO. During periods where mega-cap technology stocks dominate, returns are almost indistinguishable.
Expense Ratios & Cost Efficiency
Both ETFs have an identical expense ratio of 0.03%, making cost a non-factor in choosing between them. Because expenses are equal, the decision primarily comes down to whether you want exposure to small- and mid-cap stocks.
Should You Own Both VTI and VOO?
Because overlap exceeds 85%, owning both does not significantly increase diversification. Instead, it simply increases your allocation to large-cap stocks.
Most investors choose one:
- Choose VOO if you want pure large-cap exposure.
- Choose VTI if you want full U.S. market exposure in one ETF.
Watch out: Holding both VTI and VOO essentially doubles down on the same large-cap stocks. You're paying for two funds but getting almost identical core exposure — the small/mid-cap slice in VTI only accounts for roughly 15–20% of its weight.
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