IWM vs VB: 25% overlap
iShares Russell 2000 ETF and Vanguard Small-Cap ETF share 25.2% 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 1.7. Two funds that shared nothing would score 2.0; two identical funds score 1.0.
Top shared holdings
IWM and VB hold 682 of the same securities. The ten contributing most to the overlap figure:
| Holding | in IWM | in VB | Δ |
|---|---|---|---|
| CASH | 0.2% | 1.7% | 1.6% |
| MOG-A | 0.4% | 0.1% | 0.2% |
| HUT | 0.4% | 0.1% | 0.2% |
| VSAT | 0.3% | 0.1% | 0.2% |
| CYTK | 0.3% | 0.1% | 0.2% |
| BTSG | 0.4% | 0.1% | 0.2% |
| MXL | 0.3% | 0.1% | 0.1% |
| AGX | 0.3% | 0.1% | 0.1% |
| KRYS | 0.3% | 0.1% | 0.1% |
| UMBF | 0.3% | 0.1% | 0.2% |
Where IWM and VB 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 | IWM | VB | Δ |
|---|---|---|---|
| Health Care | 19.9% | 11.9% | +7.9pp |
| Industrials | 14.7% | 21.0% | −6.3pp |
| Financials | 19.0% | 12.7% | +6.3pp |
| Information Technology | 12.8% | 16.1% | −3.3pp |
| Energy | 6.1% | 3.7% | +2.4pp |
| Cash and/or Derivatives | 0.2% | 1.7% | −1.6pp |
| Consumer Staples | 2.2% | 3.5% | −1.3pp |
| Real Estate | 5.9% | 7.1% | −1.2pp |
Δ is IWM minus VB, 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
31.1% of IWM by weight, held in no part of VB.
73.2% of VB by weight, held in no part of IWM.
A large count with a small weight is the usual shape: the positions one fund adds are typically its smallest ones.
Concentration and cost
| IWM | VB | |
|---|---|---|
| Top 10 holdings | 3.3% | 5.6% |
| Positions held | 1,967 | 1,308 |
| Cost per $10,000 held, per year | $19 | $3 |
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 IWM and VB overlap?
IWM and VB overlap 25.2% by portfolio weight — moderate overlap. They share 682 holdings. The figure comes from current issuer holdings files (IWM as of 2026-07-23, VB as of 2026-06-30).
How is the overlap between IWM and VB calculated?
As the sum of the smaller weight in each fund, over every holding both funds own: Σ min(wA, wB). If IWM holds a stock at 6% and VB 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 IWM and VB?
That depends on your goals — we state facts, not advice. At 25.2% overlap, each fund still contributes meaningfully distinct exposure.
What does IWM own that VB doesn't?
IWM holds 1,967 positions and VB holds 1,308; 1,284 of IWM's positions don't appear in VB at all, and they are 31.1% of IWM by weight.
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Related comparisons
Sources: issuer holdings files, IWM as of 2026-07-23, VB as of 2026-06-30. Weights are fractions of each fund. Diagnostics, not advice.