Quick Comparison
| Feature | VOO | SPY |
|---|---|---|
| Index | S&P 500 | S&P 500 |
| Holdings | ~500 | ~500 |
| Holdings Overlap | ~97–100% | |
| Expense Ratio | 0.03% | 0.09% |
| Liquidity | Very High | Extremely High |
| Structure | Open-End ETF | Unit Investment Trust |
How Much Do VOO and SPY Overlap?
Since both ETFs track the exact same index — the S&P 500 — their holdings are virtually identical. Top positions such as Apple, Microsoft, Amazon, Nvidia, Alphabet, and Meta appear in both funds at nearly identical weights.
In practical terms, owning both VOO and SPY does not increase diversification. It simply duplicates your exposure to the same large-cap U.S. companies.
Key insight: VOO and SPY are functionally interchangeable. The difference comes down to fees, fund structure, and liquidity — not what you own, but how much you pay for it.
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Expense Ratio & Long-Term Costs
VOO charges 0.03% while SPY charges 0.09% — a difference of 0.06% per year. While this seems small, it compounds significantly over time.
On a $100,000 portfolio over 30 years, that 0.06% gap can cost several thousand dollars in lost returns. For buy-and-hold investors, VOO's lower expense ratio provides a clear cost advantage.
Liquidity & Trading
SPY is the most heavily traded ETF in the world, with daily volumes that dwarf VOO. This makes SPY the preferred choice for active traders and institutional investors who need tight bid-ask spreads and deep order books.
For long-term investors who buy and hold, VOO's liquidity is more than sufficient. The difference in trading costs is negligible for typical portfolio transactions.
Fund Structure Differences
SPY is structured as a Unit Investment Trust (UIT), which means it cannot reinvest dividends between distribution dates and cannot lend out securities. VOO is structured as an open-end fund, giving Vanguard more flexibility to reinvest dividends immediately and engage in securities lending — both of which can provide a slight performance edge over time.
Should You Own Both VOO and SPY?
There is no diversification benefit to owning both. They hold the same stocks at the same weights. Choosing one comes down to your priorities:
- Choose VOO if you prioritize the lowest possible expense ratio for long-term holding.
- Choose SPY if you need maximum liquidity for active trading or options strategies.
Bottom line: For the vast majority of long-term investors, VOO is the better choice. You get the exact same S&P 500 exposure at one-third the cost. SPY's liquidity advantage only matters if you're trading frequently or in very large volumes.
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