ACLS vs SPY: Correlation
Axcelis Technologies, Inc. (ACLS) and SPDR S&P 500 ETF Trust (SPY) show a moderate relationship: their 3-year correlation of weekly returns is 0.44.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are ACLS and SPY?
Across a 3-year window, the weekly returns of ACLS and SPY correlate at 0.44, moderate. Lately the two have drifted apart, with the 1-year correlation at 0.23 versus 0.44 over 3 years. Stretching to 5 years gives 0.53, with an annualized covariance of 327.3 %².
Out of 11 assets tracked against ACLS, SPY lands near the bottom at #7. The last year tells two different stories: ACLS led by 28.8 percentage points, +49.4% for ACLS against +20.6% for SPY. Note the risk asymmetry: ACLS runs 3.6 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.
ACLS vs SPY: side by side
| ACLS (Axcelis Technologies, Inc.) | SPY (SPDR S&P 500 ETF Trust) | |
|---|---|---|
| 1-year return | +49.4% | +20.6% |
| 5-year return | +140.5% | +82.4% |
| Volatility (ann.) | 51.6% | 14.5% |
| Beta vs S&P 500 | 1.57 | 1.00 |
| Max drawdown (3Y) | -78.0% | -18.8% |
| Market cap | $3.8B | – |
| P/E (trailing) | 40.4 | – |
| 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 | ACLS | SPY |
|---|---|---|
| 2022 | +6.4% | -18.2% |
| 2023 | +63.4% | +26.2% |
| 2024 | -46.1% | +24.9% |
| 2025 | +15.0% | +17.7% |
| 2026 | +52.4% | +13.7% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are ACLS and SPY good diversifiers for each other?
Reasonably. At 0.44, ACLS and SPY keep a meaningful degree of independence, and combining them has historically reduced portfolio volatility.
FAQ
What is the correlation between ACLS and SPY?
The ACLS/SPY correlation stands at 0.44 on a 3-year window (1 year: 0.23, 5 years: 0.53), computed from weekly returns as of 2026-08-27.
Is SPY a good diversifier for ACLS?
Reasonably. At 0.44, ACLS and SPY keep a meaningful degree of independence, and combining them has historically reduced portfolio volatility.
What does a correlation of 0.44 mean?
A reading of 0.44 sits on a scale from −1 (opposite moves) through 0 (unrelated) to +1 (identical moves). Correlation captures direction, not magnitude or performance.
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Related comparisons
Hubs: ACLS correlations · SPY correlations
