MDY vs NNBR: Correlation
Measured on weekly returns over the past three years, SPDR S&P MidCap 400 ETF (MDY) and NN, Inc. (NNBR) carry a correlation of 0.50, a moderate link.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are MDY and NNBR?
On 3 years of weekly data the MDY/NNBR correlation comes out at 0.50, moderate. Little has changed lately, as the 1-year reading of 0.42 lands near the 3-year figure. The 5-year figure is 0.43, and annualized covariance runs at 631.6 %².
Within MDY's tracked universe of 359 assets, NNBR comes in at #294 by 3-year correlation. The last year tells two different stories: NNBR led by 21.7 percentage points, +18.3% for MDY against +40.0% for NNBR. Risk is not evenly split, since NNBR carries 4.6 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 NNBR: side by side
| MDY (SPDR S&P MidCap 400 ETF) | NNBR (NN, Inc.) | |
|---|---|---|
| 1-year return | +18.3% | +40.0% |
| 5-year return | +47.5% | -34.0% |
| Volatility (ann.) | 16.5% | 76.0% |
| Beta vs S&P 500 | 0.91 | 2.49 |
| Max drawdown (3Y) | -24.0% | -77.8% |
| Market cap | – | $0.3B |
| P/E (trailing) | – | – |
| Dividend yield | 1.02% | 0.00% |
| 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 | NNBR |
|---|---|---|
| 2022 | -13.3% | -63.4% |
| 2023 | +16.1% | +166.7% |
| 2024 | +13.6% | -18.3% |
| 2025 | +7.2% | -60.9% |
| 2026 | +16.4% | +178.9% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are MDY and NNBR good diversifiers for each other?
Somewhat, no more. With 0.50 correlation, most large moves hit both names, and the diversification benefit stays modest.
FAQ
What is the correlation between MDY and NNBR?
As of 2026-08-27, the correlation of weekly returns between MDY and NNBR is 0.50 over 3 years, 0.42 over 1 year and 0.43 over 5 years.
Is NNBR a good diversifier for MDY?
Somewhat, no more. With 0.50 correlation, most large moves hit both names, and the diversification benefit stays modest.
What does a correlation of 0.50 mean?
A reading of 0.50 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-nnbr.json
Drop this badge in a README or notebook; it updates with the data:
[](https://www.pairbook.io/pair/mdy-vs-nnbr/)
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Related comparisons
Hubs: MDY correlations · NNBR correlations
