IWM vs VOO: how much do they really overlap?
IWM (iShares Russell 2000 ETF, tracking the Russell 2000) and VOO (Vanguard S&P 500 ETF, tracking the S&P 500) overlap by roughly 0% by weight. 0 of IWM's top 10 holdings also appear in VOO. A 50/50 blend of the two behaves like about 184 equally-weighted bets (diversification grade A). In short, the two funds hold almost none of the same securities — they are complementary, not redundant.
The same companies, in both funds
These 0 holdings appear in both IWM and VOO. The weight columns show how much of each fund each name represents.
| Holding | in IWM | in VOO |
|---|
Only in IWM
iShares Russell 2000 ETF — US small-cap. Its biggest holdings that VOO doesn’t have:
| MOGA MOOG INC CLASS A | 0.38% |
| HUT HUT CORP | 0.37% |
| VSAT VIASAT INC | 0.35% |
| BTSG BRIGHTSPRING HEALTH SERVICES INC | 0.35% |
| CYTK CYTOKINETICS INC | 0.35% |
| MXL MAXLINEAR INC | 0.34% |
| AGX ARGAN INC | 0.34% |
| UMBF UMB FINANCIAL CORP | 0.33% |
Only in VOO
Vanguard S&P 500 ETF — US large-cap. Its biggest holdings that IWM doesn’t have:
| NVDA NVIDIA Corp. | 7.89% |
| AAPL Apple Inc. | 7.05% |
| MSFT Microsoft Corp. | 5.14% |
| AMZN Amazon.com Inc. | 4.07% |
| GOOGL Alphabet Inc. Class A | 3.41% |
| AVGO Broadcom Inc. | 3.26% |
| GOOG Alphabet Inc. Class C | 2.71% |
| META Facebook Inc. Class A | 2.13% |
So — essentially different. Should you hold both?
IWM and VOO hold almost none of the same securities — they are complementary, not redundant. Held together they genuinely broaden your exposure — a 50/50 blend reaches ~184 effective positions (grade A), because they hold largely different securities.
Holdings as of — IWM: Jun 30, 2026 (iShares (BlackRock)); VOO: May 31, 2026 (Vanguard). Refreshed monthly. Overlap is measured across each fund’s largest holdings (top 50); the diffuse long tail barely moves the math.
See this for YOUR whole portfolio, free →IWM vs VOO — FAQ
- How much do IWM and VOO overlap?
- IWM and VOO overlap by approximately 0% measured by portfolio weight — that is the share of the smaller fund's holdings (by weight) that also sit inside the other. 0 of IWM's 10 largest holdings are also held by VOO. They share 0 of their listed top holdings in total.
- Is it redundant to hold both IWM and VOO?
- Because they hold almost none of the same securities — they are complementary, not redundant, holding both is not redundant — each fund covers largely different holdings, so together they broaden your exposure. A 50/50 blend has an effective 184 positions and a A diversification grade.
- What does VOO hold that IWM doesn't?
- VOO's largest holdings that IWM doesn't hold include NVDA, AAPL, MSFT, AMZN, GOOGL. Its category is US large-cap, versus IWM's US small-cap.
- Which is more concentrated, IWM or VOO?
- IWM's top 10 holdings are 26% of its listed weight; VOO's are 61%. The more concentrated fund leans harder on its largest names.