IWM vs MDY: Holdings Overlap
iShares · 1941 holdings · $82.2B · as of 2026-03-31
MDYState Street® SPDR® S&P MIDCAP 400® ETF Trust
State Street (SPDR) · 399 holdings · $27.1B · as of 2026-08-06
Holdings snapshots are 128 days apart (IWM: 2026-03-31, MDY: 2026-08-06). Weights and index membership change between snapshots, so the true current overlap is typically higher than shown. For funds tracking the same index, the gap can be 5–15 points.
How similar are IWM and MDY?
iShares Russell 2000 ETF (IWM, by iShares) holds 1941 positions; State Street® SPDR® S&P MIDCAP 400® ETF Trust (MDY, by State Street (SPDR)) holds 399. They have 95 holdings in common, and by portfolio weight the two funds are 17.4% identical. In practical terms the pair is lightly overlapping, with most of each portfolio distinct.
- Overlap by Weight
- 17.4%Sum of the smaller weight of each shared holding
- Shared Holdings
- 95IWM holds 1941 · MDY holds 399
- Weight in Shared Holdings
- IWM 20%·MDY 19%Share of each fund's weight in stocks both funds own
Based on each fund's latest official holdings. How is this calculated?
What makes each fund different
Only in IWM
1846 of 1941 positions (79.7% of the fund) are not held by MDY. Showing the top 30 by weight.
Sector Breakdown
| Sector | IWM | MDY |
|---|---|---|
| Industrials | 17.9% | 25.9% |
| Health Care | 16.6% | 10.3% |
| Financials | 15.3% | 16.0% |
| Information Technology | 13.6% | 15.6% |
| Consumer Discretionary | 8.0% | 11.6% |
| Other Sectors | 22.7% | 25.7% |
| Unclassified | 5.5% | 0.0% |
Share of each fund's portfolio weight by GICS-style sector, compiled from issuer fund data and our own classification of the holdings, not the issuers' published sector charts. “Unclassified” is weight we could not classify (5% of IWM, 0% of MDY).
Performance
| Fund | 1M | YTD | 1Y | 3Y (ann.) | 5Y (ann.) | 10Y (ann.) | Yield |
|---|---|---|---|---|---|---|---|
| IWM | +1.8% | +23.0% | +38.6% | +17.1% | +7.5% | +10.8% | 0.88% |
| MDY | +3.1% | +18.1% | +25.6% | +14.2% | +8.8% | +10.9% | 0.99% |
Total returns including dividends, from adjusted daily closes as of 2026-08-07. 3Y/5Y/10Y are annualized. Yield is trailing-12-month distributions over the last close. Past performance does not predict future results.
Project the growth of $10,000 in IWM vs MDY →
Shared Holdings(95)
The top 10 shared positions account for 21% of the overlap, led by FN, CDE and STRL.
 FNFabrinet | 0.64% | 0.53% | 0.53% |
|---|---|---|---|
 CDECoeur Mining, Inc. | 0.65% | 0.44% | 0.44% |
 STRLSterling Infrastructure, Inc. | 0.41% | 0.45% | 0.41% |
 NXTNextpower, Inc., Class A | 0.60% | 0.40% | 0.40% |
 TTMITTM Technologies, Inc. | 0.34% | 0.39% | 0.34% |
 AEISAdvanced Energy Industries, Inc. | 0.41% | 0.34% | 0.34% |
 DYDycom Industries, Inc. | 0.34% | 0.67% | 0.34% |
 KTOSKratos Defense & Security Solutions, Inc. | 0.43% | 0.29% | 0.29% |
 SPXCSPX Technologies, Inc. | 0.33% | 0.29% | 0.29% |
 HLHecla Mining Company | 0.40% | 0.29% | 0.29% |
 RMBSRambus, Inc. | 0.32% | 0.29% | 0.29% |
 ARWRArrowhead Pharmaceuticals, Inc. | 0.29% | 0.33% | 0.29% |
 ENSGEnsign Group, Inc. (The) | 0.38% | 0.29% | 0.29% |
 AHRAmerican Healthcare REIT, Inc. | 0.29% | 0.29% | 0.29% |
 MOG-AMoog, Inc., Class A | 0.28% | 0.64% | 0.28% |
 UMBFUMB Financial Corporation | 0.28% | 0.28% | 0.28% |
 WTSWatts Water Technologies, Inc., Class A | 0.27% | 0.28% | 0.27% |
 CYTKCytokinetics Incorporated | 0.27% | 0.30% | 0.27% |
 CTRECareTrust REIT, Inc. | 0.28% | 0.27% | 0.27% |
 SITMSiTime Corporation | 0.26% | 0.42% | 0.26% |
 VIAVViavi Solutions, Inc. | 0.26% | 0.26% | 0.26% |
 ONBOld National Bancorp | 0.26% | 0.25% | 0.25% |
 SMTCSemtech Corporation | 0.24% | 0.67% | 0.24% |
 HQYHealthEquity, Inc. | 0.24% | 0.24% | 0.24% |
 SANMSanmina Corporation | 0.24% | 0.30% | 0.24% |
Frequently Asked Questions
How much do IWM and MDY overlap?
IWM and MDY overlap by 17.4% of portfolio weight. They share 95 holdings (IWM holds 1941 positions and MDY holds 399), based on each fund's latest SEC-reported holdings.
Is it redundant to own both IWM and MDY?
The two portfolios are 17.4% identical by weight. Owning both is not redundant. Most of each portfolio is distinct, so the funds can serve different roles.
What are the biggest shared holdings of IWM and MDY?
The largest positions held by both funds are FN, CDE, STRL, NXT and TTMI. Together the top 10 shared positions account for 21% of the total overlap.
What does IWM own that MDY doesn't?
1846 positions (79.7% of IWM) are unique to IWM, led by BE, ECHO and CRDO. In the other direction, 304 positions (85.8% of MDY) are unique to MDY.