MCRB vs XBI: Correlation
Measured on weekly returns over the past three years, Seres Therapeutics, Inc. (MCRB) and SPDR S&P Biotech ETF (XBI) carry a correlation of 0.44, a moderate link.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are MCRB and XBI?
On 3 years of weekly data the MCRB/XBI correlation comes out at 0.44, moderate. Little has changed lately, as the 1-year reading of 0.46 lands near the 3-year figure. The 5-year figure is 0.42, and annualized covariance runs at 1246.6 %².
XBI is one of the assets that tracks MCRB most closely: it ranks #2 out of the 11 assets we track against MCRB. The last year tells two different stories: XBI led by 161.0 percentage points, -73.8% for MCRB against +87.2% for XBI. One caveat on sizing: MCRB is 3.7 times as volatile as the other leg, so an equal-dollar split is far from equal-risk.
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.
MCRB vs XBI: side by side
| MCRB (Seres Therapeutics, Inc.) | XBI (SPDR S&P Biotech ETF) | |
|---|---|---|
| 1-year return | -73.8% | +87.2% |
| 5-year return | -96.0% | +28.6% |
| Volatility (ann.) | 103.2% | 27.7% |
| Beta vs S&P 500 | 1.38 | 1.09 |
| Max drawdown (3Y) | -94.0% | -33.0% |
| Market cap | – | – |
| P/E (trailing) | – | – |
| Dividend yield | 0.00% | – |
| Sector / category | US Listed | ETF · Thematic |
Year-by-year returns
| Year | MCRB | XBI |
|---|---|---|
| 2022 | -32.8% | -25.9% |
| 2023 | -75.0% | +7.6% |
| 2024 | -40.6% | +1.0% |
| 2025 | -10.5% | +35.9% |
| 2026 | -66.7% | +38.1% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are MCRB and XBI good diversifiers for each other?
A fair diversifier. At 0.44, enough of each asset's movement is its own that the pair has smoothed outcomes historically.
FAQ
What is the correlation between MCRB and XBI?
As of 2026-08-27, the correlation of weekly returns between MCRB and XBI is 0.44 over 3 years, 0.46 over 1 year and 0.42 over 5 years.
Is XBI a good diversifier for MCRB?
A fair diversifier. At 0.44, enough of each asset's movement is its own that the pair has smoothed outcomes historically.
What does a correlation of 0.44 mean?
On the −1 to +1 scale, 0.44 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/mcrb-vs-xbi.json
Embed this badge (it refreshes with the data), with attribution:
[](https://www.pairbook.io/pair/mcrb-vs-xbi/)
The core API is free. Terms and every endpoint in the API documentation.
Related comparisons
Hubs: MCRB correlations · XBI correlations
