IJR vs IWM: 47% overlap
iShares Core S&P Small-Cap ETF and iShares Russell 2000 ETF share 47.3% of their portfolios by weight — computed as Σ min(wA, wB) over every holding both funds own.
You would hold two tickers and get the diversification of 1.5. Two funds that shared nothing would score 2.0; two identical funds score 1.0.
Top shared holdings
IJR and IWM hold 540 of the same securities. The ten contributing most to the overlap figure:
| Holding | in IJR | in IWM | Δ |
|---|---|---|---|
| VSAT | 0.6% | 0.3% | 0.3% |
| ALKS | 0.5% | 0.3% | 0.2% |
| ESE | 0.5% | 0.3% | 0.2% |
| GKOS | 0.5% | 0.3% | 0.2% |
| PTGX | 0.5% | 0.3% | 0.2% |
| AGX | 0.5% | 0.3% | 0.2% |
| SNEX | 0.4% | 0.3% | 0.2% |
| SM | 0.4% | 0.3% | 0.2% |
| RHP | 0.5% | 0.3% | 0.2% |
| TGTX | 0.4% | 0.3% | 0.2% |
Where IJR and IWM differ
Sector weights as a share of each fund, ordered by the size of the gap rather than the size of the sector — two funds that overlap heavily still usually diverge somewhere.
| Sector | IJR | IWM | Δ |
|---|---|---|---|
| Health Care | 10.5% | 19.9% | −9.4pp |
| Consumer Discretionary | 13.8% | 9.4% | +4.3pp |
| Industrials | 18.5% | 14.7% | +3.8pp |
| Cash and/or Derivatives | 2.1% | 0.2% | +1.9pp |
| Consumer Staples | 3.8% | 2.2% | +1.6pp |
| Financials | 17.8% | 19.0% | −1.2pp |
| Communication Services | 3.6% | 2.5% | +1.1pp |
| Energy | 5.3% | 6.1% | −0.8pp |
Δ is IJR minus IWM, in percentage points. Sector data is not published by every issuer, so “Unclassified” is a real category rather than a gap in the table.
What each fund holds alone
17.1% of IJR by weight, held in no part of IWM.
52.1% of IWM by weight, held in no part of IJR.
A large count with a small weight is the usual shape: the positions one fund adds are typically its smallest ones.
Concentration and cost
| IJR | IWM | |
|---|---|---|
| Top 10 holdings | 6.6% | 3.3% |
| Positions held | 603 | 1,967 |
| Cost per $10,000 held, per year | $6 | $19 |
Cost is the expense ratio applied to $10,000; it excludes any brokerage commission, bid-ask spread or tax consequence. Figures are facts about the funds, not a suggestion about which to hold.
Frequently asked
How much do IJR and IWM overlap?
IJR and IWM overlap 47.3% by portfolio weight — moderate overlap. They share 540 holdings. The figure comes from current issuer holdings files (IJR as of 2026-07-23, IWM as of 2026-07-23).
How is the overlap between IJR and IWM calculated?
As the sum of the smaller weight in each fund, over every holding both funds own: Σ min(wA, wB). If IJR holds a stock at 6% and IWM holds the same stock at 4%, 4% counts as shared. The result is bounded between 0% and 100%, and it is computed after looking through any fund-of-funds to the underlying holdings.
Is it redundant to hold both IJR and IWM?
That depends on your goals — we state facts, not advice. At 47.3% overlap, each fund still contributes meaningfully distinct exposure.
What does IJR own that IWM doesn't?
IJR holds 603 positions and IWM holds 1,967; 62 of IJR's positions don't appear in IWM at all, and they are 17.1% of IJR by weight.
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Related comparisons
Sources: issuer holdings files, IJR as of 2026-07-23, IWM as of 2026-07-23. Weights are fractions of each fund. Diagnostics, not advice.