IWR vs SPY: Holdings Overlap
IWRiShares Russell Mid-Cap ETF
iShares · 806 holdings · $57.6B · as of 2026-03-31
SPYState Street® SPDR® S&P 500® ETF Trust
State Street (SPDR) · 504 holdings · $812.0B · as of 2026-08-06
Holdings snapshots are 128 days apart (IWR: 2026-03-31, SPY: 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 SPY?
iShares Russell Mid-Cap ETF (IWR, by iShares) holds 806 positions; State Street® SPDR® S&P 500® ETF Trust (SPY, by State Street (SPDR)) holds 504. They have 303 holdings in common, and by portfolio weight the two funds are 14.4% identical. In practical terms the pair is lightly overlapping, with most of each portfolio distinct.
- Overlap by Weight
- 14.4%Sum of the smaller weight of each shared holding
- Shared Holdings
- 303IWR holds 806 · SPY holds 504
- Weight in Shared Holdings
- IWR 67%·SPY 15%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
503 of 806 positions (33.1% of the fund) are not held by SPY. Showing the top 30 by weight.
Sector Breakdown
| Sector | IWR | SPY |
|---|---|---|
| Information Technology | 13.0% | 37.6% |
| Industrials | 18.7% | 8.8% |
| Financials | 13.6% | 12.3% |
| Consumer Discretionary | 10.8% | 9.3% |
| Communication Services | 3.6% | 9.7% |
| Other Sectors | 39.9% | 22.3% |
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% |
| SPY | +3.4% | +14.0% | +23.7% | +21.2% | +13.3% | +15.3% | 0.97% |
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 SPY →
Shared Holdings(303)
The top 10 shared positions account for 12% of the overlap, led by SNDK, WDC and GLW.
 SNDKSandisk Corporation COM | 0.72% | 0.28% | 0.28% |
|---|---|---|---|
 WDCWestern Digital Corp. COM | 0.73% | 0.23% | 0.23% |
 GLWCorning Incorporated COM | 0.84% | 0.19% | 0.19% |
 HWMHowmet Aerospace Inc COM | 0.73% | 0.17% | 0.17% |
 BNYThe Bank of New York Mellon Corp. COM | 0.65% | 0.16% | 0.16% |
 VRTVertiv Holdings Co., Class A | 0.76% | 0.16% | 0.16% |
 PWRQuanta Services, Inc. COM | 0.64% | 0.15% | 0.15% |
 VLOValero Energy Corp. COM | 0.60% | 0.14% | 0.14% |
 CMICummins Inc. COM | 0.59% | 0.13% | 0.13% |
 MPCMarathon Petroleum Corp. COM | 0.58% | 0.13% | 0.13% |
 PSXPhillips 66 COM | 0.58% | 0.12% | 0.12% |
 ROSTRoss Stores Inc COM | 0.55% | 0.12% | 0.12% |
 RCLRoyal Caribbean Group COM USD0.01 | 0.55% | 0.12% | 0.12% |
 DDOGDatadog, Inc., Class A | 0.29% | 0.11% | 0.11% |
 HLTHilton Worldwide Holdings Inc COM | 0.55% | 0.11% | 0.11% |
 URIUnited Rentals, Inc. COM | 0.37% | 0.11% | 0.11% |
 SPGSimon Property Group Inc COM | 0.48% | 0.11% | 0.11% |
 HOODRobinhood Markets, Inc., Class A | 0.42% | 0.11% | 0.11% |
 ALLThe Allstate Corporation COM | 0.43% | 0.11% | 0.11% |
 HPEHewlett Packard Enterprise Co. COM | 0.25% | 0.10% | 0.10% |
 DLRDigital Realty Trust Inc. COM | 0.49% | 0.10% | 0.10% |
 MPWRMonolithic Power Systems Inc. COM | 0.40% | 0.10% | 0.10% |
 WBDWarner Bros. Discovery Inc. COM SER A | 0.51% | 0.10% | 0.10% |
 COHRCoherent Corp COM | 0.33% | 0.10% | 0.10% |
 LITELumentum Holdings Inc. COM | 0.39% | 0.10% | 0.10% |
Showing the top 250 of 303 shared holdings by overlap weight.
Frequently Asked Questions
How much do IWR and SPY overlap?
IWR and SPY overlap by 14.4% of portfolio weight. They share 303 holdings (IWR holds 806 positions and SPY holds 504), based on each fund's latest SEC-reported holdings.
Is it redundant to own both IWR and SPY?
The two portfolios are 14.4% 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 IWR and SPY?
The largest positions held by both funds are SNDK, WDC, GLW, HWM and BNY. Together the top 10 shared positions account for 12% of the total overlap.
What does IWR own that SPY doesn't?
503 positions (33.1% of IWR) are unique to IWR, led by NET, LNG and EA. In the other direction, 201 positions (84.9% of SPY) are unique to SPY.