MCRB vs SPY: Correlation
Measured on weekly returns over the past three years, Seres Therapeutics, Inc. (MCRB) and SPDR S&P 500 ETF Trust (SPY) carry a correlation of 0.19, a weak link.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are MCRB and SPY?
Over the past 3 years, MCRB and SPY moved with a correlation of 0.19, which is weak. Little has changed lately, as the 1-year reading of 0.12 lands near the 3-year figure. Over 5 years the correlation is 0.19, and the annualized covariance of weekly returns is 288.3 %².
SPY is close to the least connected end of MCRB's tracked universe, ranking #7 of 11. The last year tells two different stories: SPY led by 94.4 percentage points, -73.8% for MCRB against +20.6% for SPY. Note the risk asymmetry: MCRB runs 7.1 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.
MCRB vs SPY: side by side
| MCRB (Seres Therapeutics, Inc.) | SPY (SPDR S&P 500 ETF Trust) | |
|---|---|---|
| 1-year return | -73.8% | +20.6% |
| 5-year return | -96.0% | +82.4% |
| Volatility (ann.) | 103.2% | 14.5% |
| Beta vs S&P 500 | 1.38 | 1.00 |
| Max drawdown (3Y) | -94.0% | -18.8% |
| Market cap | – | – |
| P/E (trailing) | – | – |
| Dividend yield | 0.00% | 1.01% |
| Expense ratio | – | 0.09% |
| Assets under management | – | $795.3B |
| Sector / category | US Listed | ETF · US Large Cap |
SPY is a Large Blend fund from State Street Investment Management: $795.3B under management, 504 holdings, a 0.09% expense ratio, a 1.01% trailing dividend yield.
Year-by-year returns
| Year | MCRB | SPY |
|---|---|---|
| 2022 | -32.8% | -18.2% |
| 2023 | -75.0% | +26.2% |
| 2024 | -40.6% | +24.9% |
| 2025 | -10.5% | +17.7% |
| 2026 | -66.7% | +13.7% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are MCRB and SPY good diversifiers for each other?
Yes: at 0.19, the two have gone their own ways historically, which is what genuine diversification looks like.
FAQ
What is the correlation between MCRB and SPY?
The MCRB/SPY correlation stands at 0.19 on a 3-year window (1 year: 0.12, 5 years: 0.19), computed from weekly returns as of 2026-08-27.
Is SPY a good diversifier for MCRB?
Yes: at 0.19, the two have gone their own ways historically, which is what genuine diversification looks like.
What does a correlation of 0.19 mean?
On the −1 to +1 scale, 0.19 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.
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Related comparisons
Hubs: MCRB correlations · SPY correlations
