ACFN vs FSS: Correlation
How closely do Acorn Energy, Inc. (ACFN) and Federal Signal Corporation (FSS) trade together? Their weekly returns over three years give a correlation of 0.31, which is moderate.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are ACFN and FSS?
On 3 years of weekly data the ACFN/FSS correlation comes out at 0.31, moderate. The relationship has been stable: the 1-year correlation (0.33) sits close to the 3-year figure. The 5-year figure is 0.21, and annualized covariance runs at 785.1 %².
Within ACFN's tracked universe of 14 assets, FSS comes in at #6 by 3-year correlation. The last year tells two different stories: FSS led by 21.7 percentage points, -27.0% for ACFN against -5.3% for FSS. Note the risk asymmetry: ACFN runs 2.6 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.
ACFN vs FSS: side by side
| ACFN (Acorn Energy, Inc.) | FSS (Federal Signal Corporation) | |
|---|---|---|
| 1-year return | -27.0% | -5.3% |
| 5-year return | +122.5% | +203.9% |
| Volatility (ann.) | 81.3% | 31.2% |
| Beta vs S&P 500 | 0.68 | 1.02 |
| Max drawdown (3Y) | -58.1% | -31.5% |
| Market cap | $0.1B | $7.3B |
| P/E (trailing) | 33.9 | 26.2 |
| Dividend yield | 0.00% | 0.48% |
| Sector / category | US Listed | US Listed |
Year-by-year returns
| Year | ACFN | FSS |
|---|---|---|
| 2022 | -44.4% | +8.2% |
| 2023 | +8.8% | +66.3% |
| 2024 | +193.8% | +21.1% |
| 2025 | -15.6% | +18.2% |
| 2026 | +36.8% | +11.3% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are ACFN and FSS good diversifiers for each other?
A fair diversifier. At 0.31, enough of each asset's movement is its own that the pair has smoothed outcomes historically.
FAQ
What is the correlation between ACFN and FSS?
The ACFN/FSS correlation stands at 0.31 on a 3-year window (1 year: 0.33, 5 years: 0.21), computed from weekly returns as of 2026-08-27.
Is FSS a good diversifier for ACFN?
A fair diversifier. At 0.31, enough of each asset's movement is its own that the pair has smoothed outcomes historically.
What does a correlation of 0.31 mean?
A reading of 0.31 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: ACFN correlations · FSS correlations
