AZZ vs MDY: Correlation
How closely do AZZ Inc. (AZZ) and SPDR S&P MidCap 400 ETF (MDY) trade together? Their weekly returns over three years give a correlation of 0.64, which is strong.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are AZZ and MDY?
Across a 3-year window, the weekly returns of AZZ and MDY correlate at 0.64, strong. Recent behaviour matches the longer record: 0.63 over 1 year against 0.64 over 3. Stretching to 5 years gives 0.66, with an annualized covariance of 344.2 %².
Few assets follow AZZ as closely as MDY, which ranks #1 of 11 tracked partners. Neither side won the trailing year by much: +20.8% against +18.3%. One caveat on sizing: AZZ is 2.0 times as volatile as the other leg, so an equal-dollar split is far from equal-risk.
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.
AZZ vs MDY: side by side
| AZZ (AZZ Inc.) | MDY (SPDR S&P MidCap 400 ETF) | |
|---|---|---|
| 1-year return | +20.8% | +18.3% |
| 5-year return | +177.7% | +47.5% |
| Volatility (ann.) | 32.5% | 16.5% |
| Beta vs S&P 500 | 1.09 | 0.91 |
| Max drawdown (3Y) | -23.7% | -24.0% |
| Market cap | $4.2B | – |
| P/E (trailing) | 21.5 | – |
| Dividend yield | 0.57% | 1.02% |
| Expense ratio | – | 0.23% |
| Assets under management | – | $26.5B |
| Sector / category | US Listed | ETF · US Small & Mid Cap |
MDY, State Street Investment Management's Mid-Cap Blend fund, carries $26.5B under management, 400 holdings, a 0.23% expense ratio, a 1.02% trailing dividend yield.
Year-by-year returns
| Year | AZZ | MDY |
|---|---|---|
| 2022 | -26.1% | -13.3% |
| 2023 | +46.8% | +16.1% |
| 2024 | +42.3% | +13.6% |
| 2025 | +31.9% | +7.2% |
| 2026 | +31.0% | +16.4% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are AZZ and MDY good diversifiers for each other?
Somewhat, no more. With 0.64 correlation, most large moves hit both names, and the diversification benefit stays modest.
FAQ
What is the correlation between AZZ and MDY?
Using weekly returns as of 2026-08-27: 0.64 over 3 years, with 0.63 over the last year and 0.66 over 5 years.
Is MDY a good diversifier for AZZ?
Somewhat, no more. With 0.64 correlation, most large moves hit both names, and the diversification benefit stays modest.
What does a correlation of 0.64 mean?
On the −1 to +1 scale, 0.64 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: AZZ correlations · MDY correlations
