EFA vs IBB: Correlation & Overlap
How closely do iShares MSCI EAFE ETF (EFA) and iShares Biotechnology ETF (IBB) trade together? Their weekly returns over three years give a correlation of 0.59, which is moderate. Looking through to holdings, 0.4% of the two portfolios is the same by weight.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are EFA and IBB?
Over the past 3 years, EFA and IBB moved with a correlation of 0.59, which is moderate. The past 12 months show a weaker link (0.45) than the 3-year average (0.59). Over 5 years the correlation is 0.62, and the annualized covariance of weekly returns is 181.5 %².
By 3-year correlation, IBB places #67 of the 109 assets tracked against EFA. Correlation aside, the last 12 months split them widely, with IBB ahead by 33.5 points (+21.9% versus +55.4%). Across three years, the rolling one-year figure varied moderately, from 0.51 to 0.79.
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.
EFA vs IBB: side by side
| EFA (iShares MSCI EAFE ETF) | IBB (iShares Biotechnology ETF) | |
|---|---|---|
| 1-year return | +21.9% | +55.4% |
| 5-year return | +56.7% | +26.6% |
| Volatility (ann.) | 14.9% | 20.7% |
| Beta vs S&P 500 | 0.77 | 0.81 |
| Max drawdown (3Y) | -14.1% | -24.9% |
| Dividend yield | 3.19% | 0.22% |
| Expense ratio | 0.32% | 0.44% |
| Assets under management | $78.0B | $9.2B |
| Sector / category | ETF · International | ETF · Thematic |
EFA is a Foreign Large Blend fund from iShares: $78.0B under management, 666 holdings, a 0.32% expense ratio, a 3.19% trailing dividend yield. IBB, iShares's Health fund, carries $9.2B under management, 235 holdings, a 0.44% expense ratio, a 0.22% trailing dividend yield.
Portfolio overlap between EFA and IBB
The two portfolios are largely distinct: 0.4% of the funds' weight sits in the same underlying holdings (4 common positions). Correlation tells you they move together; overlap tells you why.
| Common holding | Weight in EFA | Weight in IBB |
|---|---|---|
| ARGX | 0.29% | 3.76% |
| GMAB | 0.09% | 1.22% |
| ABVX | 0.03% | 0.52% |
| EBS | 0.20% | 0.02% |
Largest positions held only by EFA: ASML (2.99%), HSBA (1.57%), ROP (1.42%), SAN (1.38%), NOVN (1.28%). Only by IBB: AMGN (8.43%), VRTX (7.89%), GILD (7.10%), REGN (5.68%), MRNA (3.76%).
Overlap = sum of the smaller of the two weights across common holdings, from issuer disclosures as of 2026-08-26. Top 4 common positions shown.
Year-by-year returns
| Year | EFA | IBB |
|---|---|---|
| 2022 | -14.4% | -13.7% |
| 2023 | +18.4% | +3.8% |
| 2024 | +3.5% | -2.4% |
| 2025 | +31.5% | +28.0% |
| 2026 | +14.3% | +27.4% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are EFA and IBB good diversifiers for each other?
Somewhat, no more. With 0.59 correlation, most large moves hit both names, and the diversification benefit stays modest.
FAQ
What is the correlation between EFA and IBB?
As of 2026-08-27, the correlation of weekly returns between EFA and IBB is 0.59 over 3 years, 0.45 over 1 year and 0.62 over 5 years.
Is IBB a good diversifier for EFA?
Somewhat, no more. With 0.59 correlation, most large moves hit both names, and the diversification benefit stays modest.
How much do EFA and IBB overlap?
Per the issuers' own portfolio disclosures (2026-08-26), the overlap is 0.4% by weight over 4 common positions.
Use this data
$ curl https://www.pairbook.io/api/v1/pairs/efa-vs-ibb.json
Embed this badge (it refreshes with the data), with attribution:
[](https://www.pairbook.io/pair/efa-vs-ibb/)
No key needed, free to use. Full endpoint list in the API documentation.
Related comparisons
Hubs: EFA correlations · IBB correlations
