ETF comparison
IWM vs MDY
US Small Cap vs US Mid Cap.
iShares Russell 2000 ETF · State Street SPDR S&P MIDCAP 400 ETF Trust
Holdings overlap
75 positions appear in both funds. Buying equal dollars of IWM and MDY would leave roughly 11.0% of each dollar exposed to the same underlying securities.
Unmatched is the part of a fund's weight the other fund doesn't match: names only it holds, plus any extra weight it puts in names both funds hold.
Side by side
Sub-score comparison
Tracking quality isn't part of the composite — see what we don't score for why.
Cost difference
IWM is 4 bps cheaper than MDY. On a $100,000 position that's about $40/yr more in fees for MDY.
Fee figure is the annual expense charged on $100,000. To see how the gap compounds over a multi-decade holding period, open the cost calculator pre-filled with IWM vs MDY.
Top shared holdings
75 shared in total| # | Holding | In IWM | In MDY | Overlap |
|---|---|---|---|---|
| 1 | Moog, Inc. | 0.38% | 0.32% | 0.32% |
| 2 | BrightSpring Health Services, Inc. | 0.35% | 0.29% | 0.29% |
| 3 | UMB Financial Corp. | 0.33% | 0.27% | 0.27% |
| 4 | Cytokinetics, Inc. | 0.35% | 0.26% | 0.26% |
| 5 | Krystal Biotech, Inc. | 0.30% | 0.25% | 0.25% |
| 6 | CareTrust REIT, Inc. | 0.28% | 0.25% | 0.25% |
| 7 | Old National Bancorp | 0.28% | 0.24% | 0.24% |
| 8 | FirstCash Holdings, Inc. | 0.28% | 0.24% | 0.24% |
| 9 | InterDigital, Inc. | 0.23% | 0.25% | 0.23% |
| 10 | Brinker International, Inc. | 0.23% | 0.25% | 0.23% |
| 11 | HealthEquity, Inc. | 0.24% | 0.22% | 0.22% |
| 12 | Silicon Laboratories, Inc. | 0.22% | 0.21% | 0.21% |
Only in IWM
1,939 total- Hut 8 Corp. 0.37%
- Viasat, Inc. 0.35%
- MaxLinear, Inc. 0.34%
- Argan, Inc. 0.34%
- JFrog Ltd. 0.31%
- Riot Platforms, Inc. 0.30%
- ESCO Technologies, Inc. 0.29%
- Compass, Inc. 0.27%
- D-Wave Quantum, Inc. 0.27%
- Alkermes plc 0.27%
Only in MDY
326 total- Twilio Inc. Class A 1.30%
- Okta Inc. Class A 1.01%
- U.S. Dollar 0.89%
- nVent Electric plc 0.79%
- TechnipFMC plc 0.77%
- ATI Inc 0.75%
- Entegris Inc. 0.73%
- United Therapeutics Corporation 0.67%
- MACOM Technology Solutions Holdings Inc. 0.64%
- TD SYNNEX Corporation 0.64%
Related comparisons
More comparisons with IWM
- IWM vs DFAC · U.S. Core Equity 2 Portfolio-ETF Class Shares 10.1%
- IWM vs IJJ · iShares S&P Mid-Cap 400 Value ETF 9.5%
- IWM vs DON · WisdomTree U.S. MidCap Dividend Fund 8.8%
- IWM vs BBMC · JPMorgan BetaBuilders U.S. Mid Cap Equity ETF 7.5%
- IWM vs CALF · Pacer US Small Cap Cash Cows 100 ETF 7.3%
- IWM vs AVUS · Avantis US Equity ETF 6.3%
More comparisons with MDY
- MDY vs IWD · iShares Russell 1000 Value ETF 6.8%
- MDY vs VTI · Vanguard Morningstar Total Stock Market ETF 5.0%
- MDY vs ITOT · iShares Core S&P Total U.S. Stock Market ETF 4.8%
- MDY vs SCHB · Schwab U.S. Broad Market ETF 4.6%
- MDY vs VYM · Vanguard High Dividend Yield Index Fund ETF Shares 4.4%
- MDY vs DGRO · iShares Core Dividend Growth ETF 4.0%
Percentages are holdings overlap with the named fund.
Open IWM or MDY at a brokerage
Both funds trade commission-free at major US brokerages.
Affiliate links — opening an account through these earns PlainIndex a one-time referral. Scoring is computed before any affiliate consideration; see our methodology and funding disclosure.
Holdings overlap is the sum of min(weight_a, weight_b) over positions
matched on ISIN (CUSIP fallback). Methodology: see
/methodology/.
Comparing two funds doesn't endorse swapping one for the other. Tax-lot history, account type, and personal goals matter — PlainIndex publishes data and methodology, not investment advice.