MDY vs OSK: Correlation
Measured on weekly returns over the past three years, SPDR S&P MidCap 400 ETF (MDY) and Oshkosh Corporation (Holding Company) (OSK) carry a correlation of 0.68, a strong link.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are MDY and OSK?
On 3 years of weekly data the MDY/OSK correlation comes out at 0.68, strong. The relationship has been stable: the 1-year correlation (0.65) sits close to the 3-year figure. The 5-year figure is 0.69, and annualized covariance runs at 417.6 %².
By 3-year correlation, OSK places #84 of the 359 assets tracked against MDY. The trailing year gives MDY the advantage: +18.3% versus +11.0%, a 7.3-point spread. One caveat on sizing: OSK is 2.2 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.
MDY vs OSK: side by side
| MDY (SPDR S&P MidCap 400 ETF) | OSK (Oshkosh Corporation (Holding Company)) | |
|---|---|---|
| 1-year return | +18.3% | +11.0% |
| 5-year return | +47.5% | +47.4% |
| Volatility (ann.) | 16.5% | 37.0% |
| Beta vs S&P 500 | 0.91 | 1.14 |
| Max drawdown (3Y) | -24.0% | -36.7% |
| Market cap | – | $9.7B |
| P/E (trailing) | – | 18.1 |
| Dividend yield | 1.02% | 1.37% |
| Expense ratio | 0.23% | – |
| Assets under management | $26.5B | – |
| Sector / category | ETF · US Small & Mid Cap | US Listed |
On the fund side, MDY sits in the Mid-Cap Blend category at State Street Investment Management, with $26.5B under management, 400 holdings, a 0.23% expense ratio, a 1.02% trailing dividend yield.
Year-by-year returns
| Year | MDY | OSK |
|---|---|---|
| 2022 | -13.3% | -20.5% |
| 2023 | +16.1% | +25.2% |
| 2024 | +13.6% | -10.8% |
| 2025 | +7.2% | +34.5% |
| 2026 | +16.4% | +26.2% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Fund exposure
OSK represents 0.27% of MDY's portfolio, so part of any move in MDY is OSK itself, and the correlation between them is partly mechanical.
Are MDY and OSK good diversifiers for each other?
Somewhat, no more. With 0.68 correlation, most large moves hit both names, and the diversification benefit stays modest.
FAQ
What is the correlation between MDY and OSK?
As of 2026-08-27, the correlation of weekly returns between MDY and OSK is 0.68 over 3 years, 0.65 over 1 year and 0.69 over 5 years.
Is OSK a good diversifier for MDY?
Somewhat, no more. With 0.68 correlation, most large moves hit both names, and the diversification benefit stays modest.
What does a correlation of 0.68 mean?
A reading of 0.68 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: MDY correlations · OSK correlations
