IBB vs VOO: Correlation & Overlap
How closely do iShares Biotechnology ETF (IBB) and Vanguard S&P 500 ETF (VOO) trade together? Their weekly returns over three years give a correlation of 0.56, which is moderate. The two funds also share 1.0% of their portfolios by weight.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are IBB and VOO?
Across a 3-year window, the weekly returns of IBB and VOO correlate at 0.56, moderate. Lately the two have drifted apart, with the 1-year correlation at 0.36 versus 0.56 over 3 years. Stretching to 5 years gives 0.62, with an annualized covariance of 167.6 %².
Among the 168 assets we track against IBB, VOO ranks #60 by 3-year correlation. Correlation aside, the last 12 months split them widely, with IBB ahead by 34.8 points (+55.4% versus +20.6%). The rolling one-year correlation moved between 0.39 and 0.84 over the past three years, a moderate range.
How is this computed?
Pearson correlation on weekly returns: ρ(A,B) = cov(rA, rB) / (σA · σB), over windows of 52, 156 and 260 weeks. Covariance is annualized (×52) and expressed in %². Full definitions on the methodology page.
IBB vs VOO: side by side
| IBB (iShares Biotechnology ETF) | VOO (Vanguard S&P 500 ETF) | |
|---|---|---|
| 1-year return | +55.4% | +20.6% |
| 5-year return | +26.6% | +83.0% |
| Volatility (ann.) | 20.7% | 14.4% |
| Beta vs S&P 500 | 0.81 | 0.99 |
| Max drawdown (3Y) | -24.9% | -18.7% |
| Dividend yield | 0.22% | 1.07% |
| Expense ratio | 0.44% | 0.03% |
| Assets under management | $9.2B | $1,686.9B |
| Sector / category | ETF · Thematic | ETF · US Large Cap |
IBB is a Health fund from iShares: $9.2B under management, 235 holdings, a 0.44% expense ratio, a 0.22% trailing dividend yield. VOO, Vanguard's Large Blend fund, carries $1,686.9B under management, 503 holdings, a 0.03% expense ratio, a 1.07% trailing dividend yield.
Portfolio overlap between IBB and VOO
The two portfolios are largely distinct. Weighing the shared positions, 1.0% of the two funds is identical, spread across 9 common holdings. That shared book is a large part of why the returns line up.
| Common holding | Weight in IBB | Weight in VOO |
|---|---|---|
| AMGN | 8.43% | 0.32% |
| GILD | 7.10% | 0.25% |
| VRTX | 7.89% | 0.19% |
| REGN | 5.68% | 0.12% |
| BIIB | 2.23% | 0.05% |
| INCY | 1.75% | 0.03% |
| MRNA | 3.76% | 0.03% |
| TECH | 0.78% | 0.02% |
| CRL | 0.97% | 0.02% |
Largest positions held only by IBB: ARGX (3.76%), NTRA (3.19%), RVMD (2.83%), ILMN (2.34%), ALNY (2.19%). Only by VOO: NVDA (7.56%), AAPL (7.05%), MSFT (5.37%), AMZN (4.13%), GOOGL (3.25%).
Overlap = sum of the smaller of the two weights across common holdings, from issuer disclosures as of 2026-08-26. Top 9 common positions shown.
Year-by-year returns
| Year | IBB | VOO |
|---|---|---|
| 2022 | -13.7% | -18.2% |
| 2023 | +3.8% | +26.3% |
| 2024 | -2.4% | +25.0% |
| 2025 | +28.0% | +17.8% |
| 2026 | +27.4% | +13.7% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are IBB and VOO good diversifiers for each other?
Somewhat, no more. With 0.56 correlation, most large moves hit both names, and the diversification benefit stays modest.
FAQ
What is the correlation between IBB and VOO?
The IBB/VOO correlation stands at 0.56 on a 3-year window (1 year: 0.36, 5 years: 0.62), computed from weekly returns as of 2026-08-27.
Is VOO a good diversifier for IBB?
Somewhat, no more. With 0.56 correlation, most large moves hit both names, and the diversification benefit stays modest.
How much do IBB and VOO overlap?
Per the issuers' own portfolio disclosures (2026-08-26), the overlap is 1.0% by weight over 9 common positions.
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