MDY vs OC: Correlation
Measured on weekly returns over the past three years, SPDR S&P MidCap 400 ETF (MDY) and Owens Corning Inc (OC) carry a correlation of 0.71, a strong link.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are MDY and OC?
Across a 3-year window, the weekly returns of MDY and OC correlate at 0.71, strong. The relationship has been stable: the 1-year correlation (0.70) sits close to the 3-year figure. Stretching to 5 years gives 0.69, with an annualized covariance of 411.7 %².
By 3-year correlation, OC places #59 of the 359 assets tracked against MDY. The last year tells two different stories: MDY led by 21.9 percentage points, +18.3% for MDY against -3.6% for OC. Risk is not evenly split, since OC carries 2.1 times the volatility of the other side.
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 OC: side by side
| MDY (SPDR S&P MidCap 400 ETF) | OC (Owens Corning Inc) | |
|---|---|---|
| 1-year return | +18.3% | -3.6% |
| 5-year return | +47.5% | +60.3% |
| Volatility (ann.) | 16.5% | 35.1% |
| Beta vs S&P 500 | 0.91 | 1.41 |
| Max drawdown (3Y) | -24.0% | -52.5% |
| Market cap | – | $11.4B |
| P/E (trailing) | – | – |
| Dividend yield | 1.02% | 2.10% |
| Expense ratio | 0.23% | – |
| Assets under management | $26.5B | – |
| Sector / category | ETF · US Small & Mid Cap | US Listed |
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 | MDY | OC |
|---|---|---|
| 2022 | -13.3% | -4.2% |
| 2023 | +16.1% | +77.2% |
| 2024 | +13.6% | +16.6% |
| 2025 | +7.2% | -33.0% |
| 2026 | +16.4% | +30.9% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Fund exposure
Keep in mind that MDY holds OC at a 0.32% weight, which makes a slice of this correlation mechanical rather than coincidental.
Are MDY and OC good diversifiers for each other?
Somewhat, no more. With 0.71 correlation, most large moves hit both names, and the diversification benefit stays modest.
FAQ
What is the correlation between MDY and OC?
As of 2026-08-27, the correlation of weekly returns between MDY and OC is 0.71 over 3 years, 0.70 over 1 year and 0.69 over 5 years.
Is OC a good diversifier for MDY?
Somewhat, no more. With 0.71 correlation, most large moves hit both names, and the diversification benefit stays modest.
What does a correlation of 0.71 mean?
A reading of 0.71 sits on a scale from −1 (opposite moves) through 0 (unrelated) to +1 (identical moves). Correlation captures direction, not magnitude or performance.
Use this data
$ curl https://www.pairbook.io/api/v1/pairs/mdy-vs-oc.json
Embed this badge (it refreshes with the data), with attribution:
[](https://www.pairbook.io/pair/mdy-vs-oc/)
The core API is free. Terms and every endpoint in the API documentation.
Related comparisons
Hubs: MDY correlations · OC correlations
