Data as of Sep 12, 2026. Both funds on the fields they both publish, from the same sources.
IWO vs MDY: how they differ
IWO and MDY hold 4% of their weight in the same names, and IWO returned more over the year.
iShares Russell 2000 Growth ETF and SPDR S&P MidCap 400 ETF Trust.
What they hold in common
By the books each fund has filed, IWO and MDY hold 4% of their money in the same securities at the same weight.
| Holding | IWO | MDY |
|---|---|---|
| Moog, Inc. | 0.73% | 0.33% |
| EnerSys | 0.49% | 0.24% |
| FirstCash Holdings, Inc. | 0.54% | 0.23% |
| HealthEquity, Inc. | 0.46% | 0.21% |
| Hims & Hers Health, Inc. | 0.45% | 0.20% |
| InterDigital, Inc. | 0.45% | 0.20% |
| Lantheus Holdings, Inc. | 0.43% | 0.20% |
| Silicon Laboratories, Inc. | 0.44% | 0.20% |
| Commvault Systems, Inc. | 0.38% | 0.16% |
| Novanta, Inc. | 0.35% | 0.16% |
| Fluor Corp. | 0.14% | 0.20% |
| Qualys, Inc. | 0.30% | 0.13% |
| Only in IWO | Only in MDY |
|---|---|
| BrightSpring Health Services, Inc. 0.68% | TWILIO INC 0.86% |
| MaxLinear, Inc. 0.67% | CARPENTER TECHNOLOGY CORP 0.85% |
| Argan, Inc. 0.66% | MKS INC 0.83% |
| JFrog Ltd. 0.60% | CURTISS-WRIGHT CORP 0.77% |
| Krystal Biotech, Inc. 0.58% | ENTEGRIS INC 0.76% |
| ESCO Technologies, Inc. 0.56% | NVENT ELECTRIC PLC 0.76% |
| D-Wave Quantum, Inc. 0.53% | ATI INC 0.74% |
| StoneX Group, Inc. 0.52% | ILLUMINA INC 0.73% |
Weight overlap is an ETFIQ calculation: for every security both funds hold, the smaller of the two weights, summed. Above 50%, holding both is close to holding one of them twice. Holdings dated Jun 30, 2026.
| IWO iShares Russell 2000 Growth ETF | MDY SPDR S&P MidCap 400 ETF Trust | |
|---|---|---|
| Where it sits | Core index fund | Core index fund |
| Issuer | iShares | State Street |
| What it is | Russell 2000 Growth | S&P MidCap 400, book from IJH |
| Total return, 1 year | +17.0% | +13.0% |
| S&P 500 over the same days | +17.5% | +17.5% |
| Gap to the S&P 500 | −0.5 pts | −4.5 pts |
| Expense ratio | 0.24% | 0.23% |
| Already in the S&P 500 | 0.0% | 0.0% |
| Holdings | 1133 | 400 |
IWO in plain words
IWO is an index equity fund tracking the Russell 2000 Growth. Over the year to Sep 11, 2026 it returned +17.0% with distributions reinvested, against +17.5% for the S&P 500 and +23.0% for the Nasdaq-100. The prospectus expense ratio is 0.24% a year. By its holdings filed for Jun 30, 2026, 0% of the fund by weight is stocks the S&P 500 also holds, across 1133 positions, with the top ten at 6.1%. It sat 7.1% below its high of Aug 14, 2026 on Sep 11, 2026.
MDY in plain words
MDY is an index equity fund tracking the S&P MidCap 400. Over the year to Sep 11, 2026 it returned +13.0% with distributions reinvested, against +17.5% for the S&P 500 and +23.0% for the Nasdaq-100. The prospectus expense ratio is 0.23% a year. By its holdings filed for Jun 30, 2026, 0% of the fund by weight is stocks the S&P 500 also holds, across 400 positions, with the top ten at 7.7%. It sat 5.3% below its high of Aug 14, 2026 on Sep 11, 2026.
Questions people ask
- Which returned more over the last year, IWO or MDY?
- In the year to Sep 12, 2026, with distributions reinvested, IWO returned +17.0% and MDY returned +13.0%, so IWO returned more. One year is one year; the longer windows are in the table.
- Which is cheaper, IWO or MDY?
- IWO charges 0.24% a year and MDY charges 0.23%, so MDY is cheaper. Fees come from each fund's prospectus.
- How much do IWO and MDY overlap with the S&P 500?
- By their latest filed holdings, 0% of IWO and 0% of MDY by weight is stocks the S&P 500 already holds. Between the two funds, 4% of their books are the same securities at the same weight.
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Where these figures came from
ETFIQ links to the documents behind every figure. It is not affiliated with any issuer, and a link is not an endorsement.
Cite this page. ETFIQ, IWO against MDY, data as of Sep 12, 2026. https://etfiq.com/compare/any/IWO-MDY Free to use with attribution; the underlying files are at Open data.
A comparison is not a recommendation. Standards and sources