IBB vs IEFA: Correlation & Overlap
Measured on weekly returns over the past three years, iShares Biotechnology ETF (IBB) and iShares Core MSCI EAFE ETF (IEFA) carry a correlation of 0.59, a moderate link. By holdings, the two funds overlap 0.4% by weight.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are IBB and IEFA?
On 3 years of weekly data the IBB/IEFA correlation comes out at 0.59, moderate. The link has loosened recently: the 1-year correlation (0.46) runs below the 3-year figure (0.59). The 5-year figure is 0.62, and annualized covariance runs at 183.0 %².
By 3-year correlation, IEFA places #38 of the 168 assets tracked against IBB. Their recent paths diverged sharply: over the last 12 months IBB outperformed by 33.6 percentage points (+55.4% for IBB against +21.8% for IEFA). The rolling one-year correlation moved between 0.52 and 0.79 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 IEFA: side by side
| IBB (iShares Biotechnology ETF) | IEFA (iShares Core MSCI EAFE ETF) | |
|---|---|---|
| 1-year return | +55.4% | +21.8% |
| 5-year return | +26.6% | +54.5% |
| Volatility (ann.) | 20.7% | 15.0% |
| Beta vs S&P 500 | 0.81 | 0.77 |
| Max drawdown (3Y) | -24.9% | -13.8% |
| Dividend yield | 0.22% | 3.35% |
| Expense ratio | 0.44% | 0.07% |
| Assets under management | $9.2B | $190.1B |
| Sector / category | ETF · Thematic | ETF · International |
IBB, iShares's Health fund, carries $9.2B under management, 235 holdings, a 0.44% expense ratio, a 0.22% trailing dividend yield. IEFA, iShares's Foreign Large Blend fund, carries $190.1B under management, 1620 holdings, a 0.07% expense ratio, a 3.35% trailing dividend yield.
Portfolio overlap between IBB and IEFA
The two portfolios are largely distinct. Weighing the shared positions, 0.4% of the two funds is identical, spread across 4 common holdings. That shared book is a large part of why the returns line up.
| Common holding | Weight in IBB | Weight in IEFA |
|---|---|---|
| ARGX | 3.76% | 0.25% |
| GMAB | 1.22% | 0.08% |
| ABVX | 0.52% | 0.03% |
| EBS | 0.02% | 0.17% |
Largest positions held only by IBB: AMGN (8.43%), VRTX (7.89%), GILD (7.10%), REGN (5.68%), MRNA (3.76%). Only by IEFA: ASML (2.57%), HSBA (1.35%), ROP (1.22%), SAN (1.17%), NOVN (1.10%).
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 | IBB | IEFA |
|---|---|---|
| 2022 | -13.7% | -15.2% |
| 2023 | +3.8% | +18.0% |
| 2024 | -2.4% | +3.3% |
| 2025 | +28.0% | +32.1% |
| 2026 | +27.4% | +14.5% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are IBB and IEFA good diversifiers for each other?
Only partially. A correlation of 0.59 means IBB and IEFA share most of their swings. Pairing them dampens volatility somewhat, but it will not protect against a common drawdown.
FAQ
What is the correlation between IBB and IEFA?
The IBB/IEFA correlation stands at 0.59 on a 3-year window (1 year: 0.46, 5 years: 0.62), computed from weekly returns as of 2026-08-27.
Is IEFA a good diversifier for IBB?
Only partially. A correlation of 0.59 means IBB and IEFA share most of their swings. Pairing them dampens volatility somewhat, but it will not protect against a common drawdown.
How much do IBB and IEFA 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/ibb-vs-iefa.json
Drop this badge in a README or notebook; it updates with the data:
[](https://www.pairbook.io/pair/ibb-vs-iefa/)
The core API is free. Terms and every endpoint in the API documentation.
Related comparisons
Hubs: IBB correlations · IEFA correlations
