IWM vs SWTSX: 4% overlap
iShares Russell 2000 ETF and Schwab Total Stock Market Index share 3.9% 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 3 months apart — SWTSX as of 2026-04-30, 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 SWTSX hold 1,653 of the same securities. The ten contributing most to the overlap figure:
| Holding | in IWM | in SWTSX | Δ |
|---|---|---|---|
| CASH | 0.2% | 0.1% | 0.0% |
| AGX | 0.3% | 0.0% | 0.3% |
| UMBF | 0.3% | 0.0% | 0.3% |
| VSAT | 0.3% | 0.0% | 0.3% |
| CTRE | 0.3% | 0.0% | 0.3% |
| MOG-A | 0.4% | 0.0% | 0.4% |
| FLR | 0.2% | 0.0% | 0.2% |
| FCFS | 0.3% | 0.0% | 0.3% |
| LUMN | 0.2% | 0.0% | 0.2% |
| ESE | 0.3% | 0.0% | 0.3% |
Where IWM and SWTSX 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 | SWTSX | Δ |
|---|---|---|---|
| Information Technology | 12.8% | 32.3% | −19.4pp |
| Health Care | 19.9% | 8.7% | +11.2pp |
| Communication Services | 2.5% | 10.1% | −7.6pp |
| Financials | 19.0% | 11.9% | +7.2pp |
| Industrials | 14.7% | 9.4% | +5.3pp |
| Real Estate | 5.9% | 2.3% | +3.6pp |
| Unclassified | 0.0% | 3.4% | −3.4pp |
| Materials | 4.2% | 1.6% | +2.6pp |
Δ is IWM minus SWTSX, 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
9.2% of IWM by weight, held in no part of SWTSX.
95.9% of SWTSX 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 | SWTSX | |
|---|---|---|
| Top 10 holdings | 3.3% | 33.9% |
| Positions held | 1,967 | 2,939 |
| 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 SWTSX overlap?
IWM and SWTSX overlap 3.9% by portfolio weight — largely distinct portfolios. They share 1,653 holdings. The figure comes from current issuer holdings files (IWM as of 2026-07-23, SWTSX as of 2026-04-30).
How is the overlap between IWM and SWTSX 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 SWTSX 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 SWTSX?
That depends on your goals — we state facts, not advice. At 3.9% overlap, each fund still contributes meaningfully distinct exposure.
What does IWM own that SWTSX doesn't?
IWM holds 1,967 positions and SWTSX holds 2,939; 313 of IWM's positions don't appear in SWTSX at all, and they are 9.2% of IWM by weight.
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Related comparisons
Sources: issuer holdings files, IWM as of 2026-07-23, SWTSX as of 2026-04-30. Weights are fractions of each fund. Diagnostics, not advice.