IWM vs IWO Overlap
Both funds come from IShares. IWM is an equity ETF, while IWO is a U.S. growth equity ETF. IWM and IWO show heavy overlap, with an estimated weighted overlap of 56.61%. They share 1072 holdings in the loaded dataset, led by BE, FN, and CRDO.
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Quick Answer
Both funds come from IShares. IWM is an equity ETF, while IWO is a U.S. growth equity ETF. IWM and IWO show heavy overlap, with an estimated weighted overlap of 56.61%. They share 1072 holdings in the loaded dataset, led by BE, FN, and CRDO.
- 56.61% weighted overlap across 1072 shared holdings.
- The top three shared holdings explain 4.2% of the measured overlap.
- IWM and IWO are closer in breadth than a broad-vs-niche ETF pair.
- 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
- IWM holdings
- Mar 12, 2026
- IWO holdings
- Mar 12, 2026
- Overlap computed
- Mar 15, 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
Both funds come from IShares. IWM is an equity ETF, while IWO is a U.S. growth equity ETF. IWM and IWO share a large chunk of the same portfolio weight. The overlap is driven by positions like BE, FN, and CRDO, so owning both may not diversify your stock exposure as much as the fund names suggest.
How They Differ
Both funds come from IShares. IWM is an equity ETF, while IWO is a U.S. growth equity ETF. Neither fund clearly dominates on breadth, so the practical difference is more about weighting, index construction, and cost. IWM has the lower expense ratio, while IWO 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 4.2% 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
Because IWM and IWO are closer in breadth, the better fit usually comes down to index methodology, issuer preference, and cost. IWM has the lower expense ratio, while IWO charges more for its exposure.
Overlap Driver Snapshot
Concentration
The top three shared holdings explain 4.2% 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 IWM and IWO.
| Holding | Name | IWM Wt. | IWO Wt. | Overlap |
|---|---|---|---|---|
| BE | BLOOM ENERGY CLASS A CORP | 1.14% | 2.22% | 1.14% |
| FN | FABRINET | 0.66% | 1.29% | 0.66% |
| CRDO | CREDO TECHNOLOGY GROUP HOLDING LTD | 0.58% | 1.14% | 0.58% |
| NXT | NEXTPOWER INC CLASS A | 0.56% | 0.88% | 0.56% |
| KTOS | KRATOS DEFENSE AND SECURITY SOLUTI | 0.54% | 1.06% | 0.54% |
| CDE | COEUR MINING INC | 0.50% | 0.49% | 0.49% |
| STRL | STERLING INFRASTRUCTURE INC | 0.41% | 0.81% | 0.41% |
| IONQ | IONQ INC | 0.40% | 0.78% | 0.40% |
| BBIO | BRIDGEBIO PHARMA INC | 0.40% | 0.78% | 0.40% |
| ENSG | ENSIGN GROUP INC | 0.40% | 0.78% | 0.40% |
Why These ETFs Overlap
Both funds come from IShares. IWM is an equity ETF, while IWO is a U.S. growth equity ETF. The overlap exists because both funds allocate meaningful weight to the same holdings. In this dataset, the biggest shared drivers are BE, FN, and CRDO, which appear in both portfolios and push the overlap score higher.
Holding both IWM and IWO may add less diversification than you expect. Many investors would choose the ETF that best matches their goal and avoid paying for duplicate exposure.
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Frequently Asked Questions About IWM and IWO
What is the overlap between IWM and IWO?+
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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.