IWM vs VBIAX: 1% overlap
iShares Russell 2000 ETF and Vanguard Balanced Index Admiral share 0.6% of their portfolios by weight — computed as Σ min(wA, wB) over every holding both funds own.
Different holding dates. These holdings were published about 4 months apart — VBIAX as of 2026-03-31, the rest through 2026-07-23. Each fund is compared using its most recent file, so any trading in between shows up as a difference.
You would hold two tickers and get the diversification of 2.0. Two funds that shared nothing would score 2.0; two identical funds score 1.0.
Top shared holdings
IWM and VBIAX hold 195 of the same securities. The ten contributing most to the overlap figure:
| Holding | in IWM | in VBIAX | Δ |
|---|---|---|---|
| CASH | 0.2% | 1.8% | 1.6% |
| MOG-A | 0.4% | 0.0% | 0.4% |
| FCFS | 0.3% | 0.0% | 0.3% |
| CMC | 0.2% | 0.0% | 0.2% |
| TEX | 0.3% | 0.0% | 0.2% |
| RIG | 0.2% | 0.0% | 0.2% |
| BTSG | 0.4% | 0.0% | 0.4% |
| VLY | 0.2% | 0.0% | 0.2% |
| MUR | 0.2% | 0.0% | 0.2% |
| BCPC | 0.2% | 0.0% | 0.2% |
Where IWM and VBIAX 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 | VBIAX | Δ |
|---|---|---|---|
| Unclassified | 0.0% | 55.1% | −55.1pp |
| Treasuries | 0.0% | 19.1% | −19.1pp |
| Health Care | 19.9% | 1.2% | +18.7pp |
| Financials | 19.0% | 3.6% | +15.4pp |
| Industrials | 14.7% | 0.7% | +14.0pp |
| Information Technology | 12.8% | 1.0% | +11.9pp |
| Consumer Discretionary | 9.4% | 0.5% | +8.9pp |
| MBS Pass-Through | 0.0% | 8.1% | −8.1pp |
Δ is IWM minus VBIAX, 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
83.7% of IWM by weight, held in no part of VBIAX.
98.7% of VBIAX 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 | VBIAX | |
|---|---|---|
| Top 10 holdings | 3.3% | 45.2% |
| Positions held | 1,967 | 5,119 |
| Cost per $10,000 held, per year | $19 | $7 |
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 VBIAX overlap?
IWM and VBIAX overlap 0.6% by portfolio weight — largely distinct portfolios. They share 195 holdings. The figure comes from current issuer holdings files (IWM as of 2026-07-23, VBIAX as of 2026-03-31).
How is the overlap between IWM and VBIAX 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 VBIAX 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 VBIAX?
That depends on your goals — we state facts, not advice. At 0.6% overlap, each fund still contributes meaningfully distinct exposure.
What does IWM own that VBIAX doesn't?
IWM holds 1,967 positions and VBIAX holds 5,119; 1,771 of IWM's positions don't appear in VBIAX at all, and they are 83.7% of IWM by weight.
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Related comparisons
Sources: issuer holdings files, IWM as of 2026-07-23, VBIAX as of 2026-03-31. Weights are fractions of each fund. Diagnostics, not advice.