CMS vs SO: Correlation
CMS Energy (CMS) and Southern Company (SO) show a very strong relationship: their 3-year correlation of weekly returns is 0.81.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are CMS and SO?
Across a 3-year window, the weekly returns of CMS and SO correlate at 0.81, very strong, meaning they move nearly in lockstep. The relationship has been stable: the 1-year correlation (0.86) sits close to the 3-year figure. Stretching to 5 years gives 0.85, with an annualized covariance of 216.3 %².
By 3-year correlation, SO places #6 of the 42 assets tracked against CMS. Twelve-month performance is nearly a tie, at -2.4% for CMS and -1.4% for SO. The rolling one-year correlation stayed in a tight band between 0.65 and 0.87 over the past three years, which points to a structural rather than episodic relationship.
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.
CMS vs SO: side by side
| CMS (CMS Energy) | SO (Southern Company) | |
|---|---|---|
| 1-year return | -2.4% | -1.4% |
| 5-year return | +23.8% | +62.6% |
| Volatility (ann.) | 16.2% | 16.5% |
| Beta vs S&P 500 | -0.01 | -0.02 |
| Max drawdown (3Y) | -13.2% | -15.0% |
| Market cap | $21.4B | $102.4B |
| P/E (trailing) | 20.8 | 21.7 |
| Dividend yield | 3.21% | 3.32% |
| Sector / category | Utilities | Utilities |
Year-by-year returns
| Year | CMS | SO |
|---|---|---|
| 2022 | +0.2% | +8.2% |
| 2023 | -5.2% | +2.2% |
| 2024 | +18.6% | +21.7% |
| 2025 | +8.1% | +9.5% |
| 2026 | +0.0% | +4.6% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are CMS and SO good diversifiers for each other?
No. With a correlation of 0.81, CMS and SO move nearly in lockstep, so holding both adds very little diversification.
FAQ
What is the correlation between CMS and SO?
The CMS/SO correlation stands at 0.81 on a 3-year window (1 year: 0.86, 5 years: 0.85), computed from weekly returns as of 2026-08-27.
Is SO a good diversifier for CMS?
No. With a correlation of 0.81, CMS and SO move nearly in lockstep, so holding both adds very little diversification.
What does a correlation of 0.81 mean?
On the −1 to +1 scale, 0.81 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: CMS correlations · SO correlations
