IWM vs VTSAX: 4% overlap
iShares Russell 2000 ETF and Vanguard Total Stock Market Index Admiral share 4.3% 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 2.0. Two funds that shared nothing would score 2.0; two identical funds score 1.0.
Top shared holdings
IWM and VTSAX hold 1,823 of the same securities. The ten contributing most to the overlap figure:
| Holding | in IWM | in VTSAX | Δ |
|---|---|---|---|
| CASH | 0.2% | 0.6% | 0.5% |
| MOG-A | 0.4% | 0.0% | 0.4% |
| HUT | 0.4% | 0.0% | 0.4% |
| VSAT | 0.3% | 0.0% | 0.3% |
| CYTK | 0.3% | 0.0% | 0.3% |
| BTSG | 0.4% | 0.0% | 0.3% |
| MXL | 0.3% | 0.0% | 0.2% |
| AGX | 0.3% | 0.0% | 0.3% |
| KRYS | 0.3% | 0.0% | 0.3% |
| UMBF | 0.3% | 0.0% | 0.3% |
Where IWM and VTSAX 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 | VTSAX | Δ |
|---|---|---|---|
| Information Technology | 12.8% | 35.2% | −22.4pp |
| Health Care | 19.9% | 9.5% | +10.3pp |
| Financials | 19.0% | 11.9% | +7.2pp |
| Communication Services | 2.5% | 9.1% | −6.5pp |
| Industrials | 14.7% | 10.4% | +4.3pp |
| Real Estate | 5.9% | 2.2% | +3.7pp |
| Energy | 6.1% | 3.1% | +3.0pp |
| Materials | 4.2% | 2.0% | +2.2pp |
Δ is IWM minus VTSAX, 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
4.9% of IWM by weight, held in no part of VTSAX.
95.2% of VTSAX 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 | VTSAX | |
|---|---|---|
| Top 10 holdings | 3.3% | 31.9% |
| Positions held | 1,967 | 3,495 |
| Cost per $10,000 held, per year | $19 | $4 |
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 VTSAX overlap?
IWM and VTSAX overlap 4.3% by portfolio weight — largely distinct portfolios. They share 1,823 holdings. The figure comes from current issuer holdings files (IWM as of 2026-07-23, VTSAX as of 2026-06-30).
How is the overlap between IWM and VTSAX 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 VTSAX 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 VTSAX?
That depends on your goals — we state facts, not advice. At 4.3% overlap, each fund still contributes meaningfully distinct exposure.
What does IWM own that VTSAX doesn't?
IWM holds 1,967 positions and VTSAX holds 3,495; 143 of IWM's positions don't appear in VTSAX at all, and they are 4.9% of IWM by weight.
You probably hold more than two funds
This page compares IWM and VTSAX. Paste your whole portfolio — brokerage, 401(k), IRA — and see the overlap across every fund at once, plus what you actually own underneath them and your own Effective Funds number. Free, no account, nothing stored.
X-ray my portfolio — free →Watch IWM vs VTSAX
We re-read both funds’ published holdings every weeknight. Leave an address and we'll tell you when what's inside actually changes.
Not sending yet — email alerts are built but switched off, and you'll be among the first when they turn on. No spam, one-click unsubscribe.
Related comparisons
Sources: issuer holdings files, IWM as of 2026-07-23, VTSAX as of 2026-06-30. Weights are fractions of each fund. Diagnostics, not advice.