ACIU vs SPY: Correlation
Measured on weekly returns over the past three years, AC Immune SA (ACIU) and SPDR S&P 500 ETF Trust (SPY) carry a correlation of 0.25, a weak link.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are ACIU and SPY?
Over the past 3 years, ACIU and SPY moved with a correlation of 0.25, which is weak. The link has loosened recently: the 1-year correlation (0.12) runs below the 3-year figure (0.25). Over 5 years the correlation is 0.28, and the annualized covariance of weekly returns is 251.0 %².
SPY is close to the least connected end of ACIU's tracked universe, ranking #7 of 11. The trailing year gives ACIU the advantage: +30.9% versus +20.6%, a 10.3-point spread. Note the risk asymmetry: ACIU runs 4.8 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.
ACIU vs SPY: side by side
| ACIU (AC Immune SA) | SPY (SPDR S&P 500 ETF Trust) | |
|---|---|---|
| 1-year return | +30.9% | +20.6% |
| 5-year return | -61.2% | +82.4% |
| Volatility (ann.) | 69.0% | 14.5% |
| Beta vs S&P 500 | 1.20 | 1.00 |
| Max drawdown (3Y) | -70.4% | -18.8% |
| Market cap | $0.3B | – |
| 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 | ACIU | SPY |
|---|---|---|
| 2022 | -58.8% | -18.2% |
| 2023 | +145.1% | +26.2% |
| 2024 | -46.0% | +24.9% |
| 2025 | +16.3% | +17.7% |
| 2026 | -13.7% | +13.7% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are ACIU and SPY good diversifiers for each other?
A fair diversifier. At 0.25, enough of each asset's movement is its own that the pair has smoothed outcomes historically.
FAQ
What is the correlation between ACIU and SPY?
Using weekly returns as of 2026-08-27: 0.25 over 3 years, with 0.12 over the last year and 0.28 over 5 years.
Is SPY a good diversifier for ACIU?
A fair diversifier. At 0.25, enough of each asset's movement is its own that the pair has smoothed outcomes historically.
What does a correlation of 0.25 mean?
On the −1 to +1 scale, 0.25 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/aciu-vs-spy.json
Embed this badge (it refreshes with the data), with attribution:
[](https://www.pairbook.io/pair/aciu-vs-spy/)
Free with attribution; caching and terms are described in the API documentation.
Related comparisons
Hubs: ACIU correlations · SPY correlations
