ITOT vs SPY Overlap
ITOT is an equity ETF from IShares, while SPY is a U.S. large-cap core ETF from SPDR. ITOT and SPY show very heavy overlap, with an estimated weighted overlap of 85.89%. They share 475 holdings in the loaded dataset, led by NVDA, AAPL, and MSFT.
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Quick Answer
ITOT is an equity ETF from IShares, while SPY is a U.S. large-cap core ETF from SPDR. ITOT and SPY show very heavy overlap, with an estimated weighted overlap of 85.89%. They share 475 holdings in the loaded dataset, led by NVDA, AAPL, and MSFT.
- 85.89% weighted overlap across 475 shared holdings.
- The top three shared holdings explain 20.14% of the measured overlap.
- SPY is the broader fund, while ITOT is more targeted.
- The overlap is mostly explained by the top shared positions rather than sector labels alone.
- Holding both may add less diversification than the fund names imply.
Data Freshness
- ITOT holdings
- Mar 12, 2026
- SPY holdings
- Mar 12, 2026
- Overlap computed
- Mar 13, 2026
- Data source
- Financial Modeling Prep
Review the methodology for the overlap formula and refresh policy.
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About These ETFs
What Stands Out In This Comparison
What This Means
ITOT is an equity ETF from IShares, while SPY is a U.S. large-cap core ETF from SPDR. ITOT and SPY are closely aligned. A large share of their portfolio weight is invested in the same companies, especially NVDA, AAPL, and MSFT, which means holding both is likely to feel similar to increasing the size of one core position.
How They Differ
ITOT is an equity ETF from IShares, while SPY is a U.S. large-cap core ETF from SPDR. SPY is the broader fund, while ITOT is the more targeted sleeve. ITOT has the lower expense ratio, while SPY charges more for its exposure.
What Drives The Overlap
The overlap is driven by a relatively small set of large shared positions. The top three shared holdings account for 20.14% of the score, which means the result is heavily influenced by the biggest common weights rather than a long tail of tiny positions.
When One May Fit Better
If you want the broader portfolio building block, SPY is usually the wider choice. If you want the more focused tilt, ITOT is the narrower expression. ITOT has the lower expense ratio, while SPY charges more for its exposure.
Overlap Driver Snapshot
Concentration
The top three shared holdings explain 20.14% of the full overlap score.
That helps show whether the score comes from a handful of giant shared positions or from a broader mix of common holdings.
Shared Sector Tilt
Sector tags are not consistently available for the biggest shared positions in this dataset, so this comparison leans more on the specific holdings than on sector labels.
Top Shared Holdings
These are the holdings contributing the most to the overlap score between ITOT and SPY.
| Holding | Name | ITOT Wt. | SPY Wt. | Overlap |
|---|---|---|---|---|
| NVDA | NVIDIA CORP | 6.84% | 7.73% | 6.84% |
| AAPL | APPLE INC | 5.87% | 6.64% | 5.87% |
| MSFT | MICROSOFT CORP | 4.59% | 5.19% | 4.59% |
| AMZN | AMAZON COM INC | 3.17% | 3.59% | 3.17% |
| GOOGL | ALPHABET INC CLASS A | 2.72% | 3.08% | 2.72% |
| AVGO | BROADCOM INC | 2.46% | 2.79% | 2.46% |
| GOOG | ALPHABET INC CLASS C | 2.17% | 2.46% | 2.17% |
| META | META PLATFORMS INC CLASS A | 2.17% | 2.45% | 2.17% |
| TSLA | TESLA INC | 1.71% | 1.93% | 1.71% |
| BRK-B | BERKSHIRE HATHAWAY INC CLASS B | 1.38% | 1.56% | 1.38% |
Why These ETFs Overlap
ITOT is an equity ETF from IShares, while SPY is a U.S. large-cap core ETF from SPDR. The overlap exists because both funds allocate meaningful weight to the same holdings. In this dataset, the biggest shared drivers are NVDA, AAPL, and MSFT, which appear in both portfolios and push the overlap score higher.
Holding both ITOT and SPY is usually redundant unless you have a very specific reason to tilt toward their shared holdings. In most cases, one ETF is enough.
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Frequently Asked Questions About ITOT and SPY
What is the overlap between ITOT and SPY?+
How many holdings do ITOT and SPY share?+
Is the ITOT and SPY overlap high?+
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How Overlap Is Calculated
A straightforward approach used by portfolio analysts.
For every stock that appears in both ETFs, we take the smaller of the two weights. Adding up all those minimums gives the total overlap percentage. A score of 100% means the two ETFs hold the exact same stocks in the same proportions.
Want the full explanation? Read the methodology page.