IBB vs PULM: Correlation
How closely do iShares Biotechnology ETF (IBB) and Pulmatrix, Inc. (PULM) trade together? Their weekly returns over three years give a correlation of -0.17, which is negative.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are IBB and PULM?
Across a 3-year window, the weekly returns of IBB and PULM correlate at -0.17, negative, meaning they tend to move in opposite directions. The link has tightened recently: the 1-year correlation (0.20) runs above the 3-year figure (-0.17). Stretching to 5 years gives -0.08, with an annualized covariance of -519.2 %².
Within IBB's tracked universe of 168 assets, PULM comes in at #160 by 3-year correlation. Their recent paths diverged sharply: over the last 12 months IBB outperformed by 124.1 percentage points (+55.4% for IBB against -68.7% for PULM). Risk is not evenly split, since PULM carries 7.0 times the volatility of the other side.
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 PULM: side by side
| IBB (iShares Biotechnology ETF) | PULM (Pulmatrix, Inc.) | |
|---|---|---|
| 1-year return | +55.4% | -68.7% |
| 5-year return | +26.6% | -90.6% |
| Volatility (ann.) | 20.7% | 144.8% |
| Beta vs S&P 500 | 0.81 | -0.18 |
| Max drawdown (3Y) | -24.9% | -88.1% |
| Market cap | – | – |
| P/E (trailing) | – | – |
| Dividend yield | 0.22% | 0.00% |
| Expense ratio | 0.44% | – |
| Assets under management | $9.2B | – |
| Sector / category | ETF · Thematic | US Listed |
IBB, iShares's Health fund, carries $9.2B under management, 235 holdings, a 0.44% expense ratio, a 0.22% trailing dividend yield.
Year-by-year returns
| Year | IBB | PULM |
|---|---|---|
| 2022 | -13.7% | -55.7% |
| 2023 | +3.8% | -52.1% |
| 2024 | -2.4% | +275.3% |
| 2025 | +28.0% | -68.1% |
| 2026 | +27.4% | -31.8% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are IBB and PULM good diversifiers for each other?
Yes. With a correlation of -0.17, IBB and PULM have moved largely independently, which makes them a genuinely diversifying pair by historical standards.
FAQ
What is the correlation between IBB and PULM?
As of 2026-08-27, the correlation of weekly returns between IBB and PULM is -0.17 over 3 years, 0.20 over 1 year and -0.08 over 5 years.
Is PULM a good diversifier for IBB?
Yes. With a correlation of -0.17, IBB and PULM have moved largely independently, which makes them a genuinely diversifying pair by historical standards.
What does a correlation of -0.17 mean?
Correlation ranges from −1 to +1. Values near +1 mean two assets move together, near 0 that they move independently, and negative values that they tend to move in opposite directions. It measures co-movement, not performance.
Use this data
$ curl https://www.pairbook.io/api/v1/pairs/ibb-vs-pulm.json
Embed this badge (it refreshes with the data), with attribution:
[](https://www.pairbook.io/pair/ibb-vs-pulm/)
The core API is free. Terms and every endpoint in the API documentation.
Related comparisons
Hubs: IBB correlations · PULM correlations
