IWR vs MDY: Holdings Overlap
IWRiShares Russell Mid-Cap ETF
iShares · 806 holdings · $57.6B · 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 (IWR: 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 IWR and MDY?
iShares Russell Mid-Cap ETF (IWR, by iShares) holds 806 positions; State Street® SPDR® S&P MIDCAP 400® ETF Trust (MDY, by State Street (SPDR)) holds 399. They have 298 holdings in common, and by portfolio weight the two funds are 20.3% identical. In practical terms the pair is lightly overlapping, with most of each portfolio distinct.
- Overlap by Weight
- 20.3%Sum of the smaller weight of each shared holding
- Shared Holdings
- 298IWR holds 806 · MDY holds 399
- Weight in Shared Holdings
- IWR 20%·MDY 85%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 IWR
508 of 806 positions (79.5% of the fund) are not held by MDY. Showing the top 30 by weight.
Sector Breakdown
| Sector | IWR | MDY |
|---|---|---|
| Industrials | 18.7% | 25.9% |
| Financials | 13.6% | 16.0% |
| Information Technology | 13.0% | 15.6% |
| Consumer Discretionary | 10.8% | 11.6% |
| Health Care | 9.2% | 10.3% |
| Other Sectors | 34.3% | 25.7% |
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.
Performance
| Fund | 1M | YTD | 1Y | 3Y (ann.) | 5Y (ann.) | 10Y (ann.) | Yield |
|---|---|---|---|---|---|---|---|
| IWR | +2.9% | +18.1% | +23.0% | +16.4% | +8.5% | +11.6% | 1.12% |
| 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 IWR vs MDY →
Shared Holdings(298)
The top 10 shared positions account for 9% of the overlap, led by FTI, UTHR and CW.
 FTITechnipFMC plc | 0.22% | 0.76% | 0.22% |
|---|---|---|---|
 UTHRUnited Therapeutics Corporation | 0.20% | 0.62% | 0.20% |
 CWCurtiss-Wright Corporation | 0.20% | 0.72% | 0.20% |
 XPOXPO, Inc. | 0.18% | 0.63% | 0.18% |
 RGLDRoyal Gold, Inc. | 0.17% | 0.49% | 0.17% |
 WWDWoodward, Inc. | 0.17% | 0.60% | 0.17% |
 USFDUS Foods Holding Corp. | 0.16% | 0.64% | 0.16% |
 BURLBurlington Stores, Inc. | 0.16% | 0.64% | 0.16% |
 MTZMasTec, Inc. | 0.16% | 0.44% | 0.16% |
 ATIATI, Inc. | 0.16% | 0.83% | 0.16% |
 CRSCarpenter Technology Corporation | 0.15% | 0.76% | 0.15% |
 ILMNIllumina, Inc. | 0.15% | 0.80% | 0.15% |
 NVTnVent Electric plc | 0.15% | 0.72% | 0.15% |
 BWXTBWX Technologies, Inc. | 0.15% | 0.42% | 0.15% |
 PEverpure, Inc., Class A | 0.15% | 0.75% | 0.15% |
 TWLOTwilio, Inc., Class A | 0.14% | 0.80% | 0.14% |
 RBARB Global, Inc. | 0.14% | 0.47% | 0.14% |
 ENTGEntegris, Inc. | 0.14% | 0.59% | 0.14% |
 AAAlcoa Corporation | 0.14% | 0.68% | 0.14% |
 OVVOvintiv, Inc. | 0.14% | 0.45% | 0.14% |
 RBCRBC Bearings Incorporated | 0.13% | 0.49% | 0.13% |
 THCTenet Healthcare Corporation | 0.13% | 0.60% | 0.13% |
 ITTITT, Inc. | 0.13% | 0.52% | 0.13% |
 RSReliance, Inc. | 0.13% | 0.58% | 0.13% |
 MKSIMKS, Inc. | 0.12% | 0.54% | 0.12% |
Showing the top 250 of 298 shared holdings by overlap weight.
Frequently Asked Questions
How much do IWR and MDY overlap?
IWR and MDY overlap by 20.3% of portfolio weight. They share 298 holdings (IWR holds 806 positions and MDY holds 399), based on each fund's latest SEC-reported holdings.
Is it redundant to own both IWR and MDY?
The two portfolios are 20.3% 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 IWR and MDY?
The largest positions held by both funds are FTI, UTHR, CW, XPO and RGLD. Together the top 10 shared positions account for 9% of the total overlap.
What does IWR own that MDY doesn't?
508 positions (79.5% of IWR) are unique to IWR, led by GLW, VRT and HWM. In the other direction, 101 positions (20.5% of MDY) are unique to MDY.