ATMU vs MDY: Correlation
Measured on weekly returns over the past three years, Atmus Filtration Technologies Inc. (ATMU) and SPDR S&P MidCap 400 ETF (MDY) carry a correlation of 0.65, a strong link.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are ATMU and MDY?
On 3 years of weekly data the ATMU/MDY correlation comes out at 0.65, strong. The link has loosened recently: the 1-year correlation (0.53) runs below the 3-year figure (0.65). The 5-year figure is n/a, and annualized covariance runs at 344.8 %².
MDY is one of the assets that tracks ATMU most closely: it ranks #2 out of the 12 assets we track against ATMU. On 12-month performance MDY holds a 8.4-point edge, +9.9% against +18.3%. One caveat on sizing: ATMU 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.
ATMU vs MDY: side by side
| ATMU (Atmus Filtration Technologies Inc.) | MDY (SPDR S&P MidCap 400 ETF) | |
|---|---|---|
| 1-year return | +9.9% | +18.3% |
| 5-year return | n/a | +47.5% |
| Volatility (ann.) | 32.4% | 16.5% |
| Beta vs S&P 500 | 1.02 | 0.91 |
| Max drawdown (3Y) | -30.2% | -24.0% |
| Market cap | $4.0B | – |
| P/E (trailing) | 19.0 | – |
| Dividend yield | 0.45% | 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 | ATMU | MDY |
|---|---|---|
| 2022 | – | -13.3% |
| 2023 | – | +16.1% |
| 2024 | +67.3% | +13.6% |
| 2025 | +33.2% | +7.2% |
| 2026 | -5.8% | +16.4% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are ATMU and MDY good diversifiers for each other?
Only partially. A correlation of 0.65 means ATMU and MDY share most of their swings. Pairing them dampens volatility somewhat, but it will not protect against a common drawdown.
FAQ
What is the correlation between ATMU and MDY?
Using weekly returns as of 2026-08-27: 0.65 over 3 years, with 0.53 over the last year and n/a over 5 years.
Is MDY a good diversifier for ATMU?
Only partially. A correlation of 0.65 means ATMU and MDY share most of their swings. Pairing them dampens volatility somewhat, but it will not protect against a common drawdown.
What does a correlation of 0.65 mean?
Correlation ranges from −1 to +1. Values near +1 mean two assets move together, near 0 that they move independently, and negative values that they tend to move in opposite directions. It measures co-movement, not performance.
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Related comparisons
Hubs: ATMU correlations · MDY correlations
