AME vs MDY: Correlation
How closely do Ametek (AME) and SPDR S&P MidCap 400 ETF (MDY) trade together? Their weekly returns over three years give a correlation of 0.63, which is strong.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are AME and MDY?
Across a 3-year window, the weekly returns of AME and MDY correlate at 0.63, strong. The relationship has been stable: the 1-year correlation (0.55) sits close to the 3-year figure. Stretching to 5 years gives 0.71, with an annualized covariance of 211.2 %².
By 3-year correlation, MDY places #8 of the 31 assets tracked against AME. On 12-month performance AME holds a 13.1-point edge, +31.4% against +18.3%. On a rolling one-year basis the correlation drifted between 0.47 and 0.78, a moderate band.
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.
AME vs MDY: side by side
| AME (Ametek) | MDY (SPDR S&P MidCap 400 ETF) | |
|---|---|---|
| 1-year return | +31.4% | +18.3% |
| 5-year return | +83.6% | +47.5% |
| Volatility (ann.) | 20.4% | 16.5% |
| Beta vs S&P 500 | 0.84 | 0.91 |
| Max drawdown (3Y) | -23.0% | -24.0% |
| Market cap | $55.9B | – |
| P/E (trailing) | 35.8 | – |
| Dividend yield | 0.53% | 1.02% |
| Expense ratio | – | 0.23% |
| Assets under management | – | $26.5B |
| Sector / category | Industrials | 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 | AME | MDY |
|---|---|---|
| 2022 | -4.3% | -13.3% |
| 2023 | +18.8% | +16.1% |
| 2024 | +10.0% | +13.6% |
| 2025 | +14.7% | +7.2% |
| 2026 | +19.1% | +16.4% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are AME and MDY good diversifiers for each other?
Somewhat, no more. With 0.63 correlation, most large moves hit both names, and the diversification benefit stays modest.
FAQ
What is the correlation between AME and MDY?
As of 2026-08-27, the correlation of weekly returns between AME and MDY is 0.63 over 3 years, 0.55 over 1 year and 0.71 over 5 years.
Is MDY a good diversifier for AME?
Somewhat, no more. With 0.63 correlation, most large moves hit both names, and the diversification benefit stays modest.
What does a correlation of 0.63 mean?
On the −1 to +1 scale, 0.63 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: AME correlations · MDY correlations
