IBB vs MCRB: Correlation
Measured on weekly returns over the past three years, iShares Biotechnology ETF (IBB) and Seres Therapeutics, Inc. (MCRB) carry a correlation of 0.39, a moderate link.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are IBB and MCRB?
Across a 3-year window, the weekly returns of IBB and MCRB correlate at 0.39, moderate. The relationship has been stable: the 1-year correlation (0.41) sits close to the 3-year figure. Stretching to 5 years gives 0.36, with an annualized covariance of 831.6 %².
Among the 168 assets we track against IBB, MCRB ranks #148 by 3-year correlation. The last year tells two different stories: IBB led by 129.2 percentage points, +55.4% for IBB against -73.8% for MCRB. Note the risk asymmetry: MCRB runs 5.0 times the annualized volatility of the other leg, so equal-weighting the two is not an equal-risk position.
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 MCRB: side by side
| IBB (iShares Biotechnology ETF) | MCRB (Seres Therapeutics, Inc.) | |
|---|---|---|
| 1-year return | +55.4% | -73.8% |
| 5-year return | +26.6% | -96.0% |
| Volatility (ann.) | 20.7% | 103.2% |
| Beta vs S&P 500 | 0.81 | 1.38 |
| Max drawdown (3Y) | -24.9% | -94.0% |
| 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 | MCRB |
|---|---|---|
| 2022 | -13.7% | -32.8% |
| 2023 | +3.8% | -75.0% |
| 2024 | -2.4% | -40.6% |
| 2025 | +28.0% | -10.5% |
| 2026 | +27.4% | -66.7% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are IBB and MCRB good diversifiers for each other?
A fair diversifier. At 0.39, enough of each asset's movement is its own that the pair has smoothed outcomes historically.
FAQ
What is the correlation between IBB and MCRB?
As of 2026-08-27, the correlation of weekly returns between IBB and MCRB is 0.39 over 3 years, 0.41 over 1 year and 0.36 over 5 years.
Is MCRB a good diversifier for IBB?
A fair diversifier. At 0.39, enough of each asset's movement is its own that the pair has smoothed outcomes historically.
What does a correlation of 0.39 mean?
On the −1 to +1 scale, 0.39 describes how much the two returns move together: +1 is lockstep, 0 is independence, negative values mean opposite directions. It says nothing about which performed better.
Use this data
$ curl https://www.pairbook.io/api/v1/pairs/ibb-vs-mcrb.json
Drop this badge in a README or notebook; it updates with the data:
[](https://www.pairbook.io/pair/ibb-vs-mcrb/)
The core API is free. Terms and every endpoint in the API documentation.
Related comparisons
Hubs: IBB correlations · MCRB correlations
