FZROX vs IWM: 4% overlap
Fidelity ZERO Total Market Index and iShares Russell 2000 ETF share 3.8% 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 — FZROX 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
FZROX and IWM hold 1,492 of the same securities. The ten contributing most to the overlap figure:
| Holding | in FZROX | in IWM | Δ |
|---|---|---|---|
| CASH | 0.6% | 0.2% | 0.5% |
| AGX | 0.0% | 0.3% | 0.3% |
| UMBF | 0.0% | 0.3% | 0.3% |
| VSAT | 0.0% | 0.3% | 0.3% |
| CTRE | 0.0% | 0.3% | 0.3% |
| FLR | 0.0% | 0.2% | 0.2% |
| MOG-A | 0.0% | 0.4% | 0.4% |
| FCFS | 0.0% | 0.3% | 0.3% |
| ESE | 0.0% | 0.3% | 0.3% |
| LUMN | 0.0% | 0.2% | 0.2% |
Where FZROX 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 | FZROX | IWM | Δ |
|---|---|---|---|
| Information Technology | 32.3% | 12.8% | +19.4pp |
| Health Care | 8.6% | 19.9% | −11.2pp |
| Communication Services | 10.1% | 2.5% | +7.6pp |
| Financials | 11.8% | 19.0% | −7.2pp |
| Industrials | 9.2% | 14.7% | −5.5pp |
| Unclassified | 3.8% | 0.0% | +3.8pp |
| Real Estate | 2.3% | 5.9% | −3.6pp |
| Materials | 1.6% | 4.2% | −2.6pp |
Δ is FZROX 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
96.1% of FZROX by weight, held in no part of IWM.
11.0% of IWM by weight, held in no part of FZROX.
A large count with a small weight is the usual shape: the positions one fund adds are typically its smallest ones.
Concentration and cost
| FZROX | IWM | |
|---|---|---|
| Top 10 holdings | 34.0% | 3.3% |
| Positions held | 2,685 | 1,967 |
| Cost per $10,000 held, per year | $0 | $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 FZROX and IWM overlap?
FZROX and IWM overlap 3.8% by portfolio weight — largely distinct portfolios. They share 1,492 holdings. The figure comes from current issuer holdings files (FZROX as of 2026-04-30, IWM as of 2026-07-23).
How is the overlap between FZROX and IWM calculated?
As the sum of the smaller weight in each fund, over every holding both funds own: Σ min(wA, wB). If FZROX 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 FZROX and IWM?
That depends on your goals — we state facts, not advice. At 3.8% overlap, each fund still contributes meaningfully distinct exposure.
What does FZROX own that IWM doesn't?
FZROX holds 2,685 positions and IWM holds 1,967; 1,192 of FZROX's positions don't appear in IWM at all, and they are 96.1% of FZROX by weight.
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Related comparisons
Sources: issuer holdings files, FZROX as of 2026-04-30, IWM as of 2026-07-23. Weights are fractions of each fund. Diagnostics, not advice.