Data as of Oct 28, 2026.
IWM vs MDY: Differences, Returns & Fees
Over the year to Oct 28, 2026, IWM returned +14.1% to MDY's +12.8%; 12% of their weight is in the same names.
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Net assets on Oct 27, 2026: $75.5bn for iShares Russell 2000 ETF and $25.9bn for SPDR S&P MidCap 400 ETF Trust.
Pair scorecard
IWM costs 0.04 points a year less; their one-year returns differ by 1.3 points; IWM is 2.9 times larger.
| Measure | IWM | MDY |
|---|---|---|
| Return | ||
| Total return, 1 year | +14.1% | +12.8% |
| Drawdown | ||
| Below its high | 7.6%, high on Aug 14, 2026 | 6.5%, high on Aug 14, 2026 |
| Benchmark | ||
| What it tracks | Russell 2000 Index | S&P MidCap 400 Index |
| Cost and size | ||
| Expense ratio | 0.19% | 0.23% |
| Net assets, as of Oct 27, 2026 | $75.5bn | $25.9bn |
| Holdings | ||
| Holdings in common | 12% | |
| Top ten holdings, share of the fund | 3.3% | 7.5% |
Holdings in common uses holdings dated Oct 27, 2026. Method
Risk and return
Jun 2, 2000 to Oct 23, 2026 · 1,377 weekly returnsEach against its own benchmark: IWM against VTWO, Oct 1, 2010 to Oct 23, 2026; MDY against IJH, Jun 2, 2000 to Oct 23, 2026.
MDY returned more: +874.6% to +656.6%. MDY swung slightly less: 20.5% to 22.3%. MDY fell slightly less at its worst: −54.9% to −57.7%.
Full scorecard
19 measures, with how each is measured Open ↓
| Measure | IWM | MDY | Edge | How it is measured |
|---|---|---|---|---|
| Return | ||||
| Total return | +656.6% | +874.6% | MDY | Price change plus distributions, reinvested. |
| Annualized | +7.9% | +9.0% | MDY | Total return as a yearly rate. |
| Price return | +438.6% | +613.7% | MDY | Price change alone, distributions left out. |
| Risk | ||||
| Volatility | 22.3% | 20.5% | MDY (slight) | Spread of weekly returns, annualized. Lower is steadier. |
| Downside deviation | 15.7% | 14.5% | MDY (slight) | Like volatility, counting only weeks below the Treasury bill rate. |
| Max drawdown | −57.7% | −54.9% | MDY (slight) | Deepest fall from a high to the low after it. |
| Upside capture | 101.0% | 99.9% | Share of its benchmark's rise caught in the weeks it rose. | |
| Downside capture | 100.5% | 100.2% | Share of its benchmark's fall taken in the weeks it fell. Lower is better. | |
| Beta | 1.01 | 1.00 | Not an edge | How far it moves for each 1% its benchmark moves. |
| R squared | 1.00 | 0.99 | Not an edge | Share of its weekly moves its benchmark explains. |
| Risk-adjusted | ||||
| Sharpe | 0.38 | 0.44 | MDY | Return above Treasury bills per unit of volatility. |
| Sortino | 0.53 | 0.62 | MDY | Return above Treasury bills per unit of downside deviation. |
| Treynor | 0.106 | 0.089 | Return above Treasury bills per unit of beta. | |
| Calmar | 0.14 | 0.16 | MDY | Annualized return divided by the max drawdown. |
| Against the benchmark | ||||
| Benchmark | VTWO | IJH | The ETF each fund is measured against. | |
| Alpha | −0.1% a year | −0.2% a year | Not significant | Yearly return beyond what its beta to the benchmark predicts. |
| Alpha t-stat | −0.36 | −0.63 | Not an edge | How sure the alpha is. Below 2, it could be chance. |
| Alpha range | −0.6% to +0.4% | −0.8% to +0.4% | Includes zero | The 95% range for the yearly alpha. |
| Information ratio | −0.02 | −0.11 | Return against its benchmark per unit of tracking error. | |
| Tracking error | 1.0% | 1.7% | Not an edge | How far weekly returns stray from the benchmark, annualized. |
Computed by ETFIQ from Tiingo daily prices and ETFIQ's distribution records, 1,377 weekly returns. Cash rate: the 13-week Treasury bill.
What they share
By the books each fund has filed, IWM and MDY hold 12% of their money in the same securities at the same weight. Holdings dated Oct 27, 2026.
half
12% in common
Only in one fund ↓
Side by side
IWM and MDY on the fields both publish, as of Oct 28, 2026. Source: ETFIQ.
IWM and MDY do different jobs. What does each one do in a portfolio?
- What each follows. IWM follows Russell 2000 Index and MDY follows S&P MidCap 400 Index.
- Holdings in common. 12% of the weight is in the same securities (holdings dated Oct 27, 2026).
- Number of holdings. IWM holds 1,977 positions and MDY holds 401.
Data as of Oct 28, 2026.
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IWM
IWM tracks the Russell 2000. Over the year to Oct 28, 2026 it returned +14.1% with distributions reinvested, against +14.3% for its benchmark, the Russell 2000 Index. The prospectus expense ratio is 0.19% a year. By its holdings published by its issuer for Oct 27, 2026, 0% of the fund by weight is stocks the S&P 500 also holds, across 1,977 positions, with the top ten at 3.3%. It sat 7.6% below its high of Aug 14, 2026 on Oct 28, 2026.
MDY
MDY tracks the S&P MidCap 400. Over the year to Oct 28, 2026 it returned +12.8% with distributions reinvested, against +13.2% for its benchmark, the S&P MidCap 400 Index. The prospectus expense ratio is 0.23% a year. By its holdings published by its issuer for Oct 27, 2026, 0% of the fund by weight is stocks the S&P 500 also holds, across 401 positions, with the top ten at 7.5%. It sat 6.5% below its high of Aug 14, 2026 on Oct 28, 2026.
Questions people ask
- Which returned more over the last year, IWM or MDY?
- In the year to Oct 28, 2026, with distributions reinvested, IWM returned +14.1% and MDY +12.8%.
- Which is cheaper, IWM or MDY?
- IWM is cheaper, by 0.04 percentage points a year. That is about $4 on $10,000 held for a year. Fees come from each fund's prospectus.
Links are sources, not endorsements. A comparison is not a recommendation.
How this is computed
Overlap adds up the smaller of the two weights for each security both funds hold.
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ETFIQ, IWM against MDY, data as of Oct 28, 2026. https://etfiq.com/compare/any/iwm-vs-mdy
ETFIQ. (Oct 28, 2026). IWM against MDY. Retrieved from https://etfiq.com/compare/any/iwm-vs-mdy
[IWM against MDY (ETFIQ, Oct 28, 2026)](https://etfiq.com/compare/any/iwm-vs-mdy)
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