MDY vs PNR: Correlation
How closely do SPDR S&P MidCap 400 ETF (MDY) and Pentair (PNR) 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 MDY and PNR?
Across a 3-year window, the weekly returns of MDY and PNR correlate at 0.63, strong. The link has loosened recently: the 1-year correlation (0.29) runs below the 3-year figure (0.63). Stretching to 5 years gives 0.69, with an annualized covariance of 293.5 %².
Within MDY's tracked universe of 359 assets, PNR comes in at #141 by 3-year correlation. Their recent paths diverged sharply: over the last 12 months MDY outperformed by 60.8 percentage points (+18.3% for MDY against -42.5% for PNR). The relationship is regime-dependent: the rolling one-year correlation swung between 0.31 and 0.87 over the past three years, so this pair behaves very differently depending on the market environment. Note the risk asymmetry: PNR runs 1.7 times the annualized volatility of the other leg, so equal-weighting the two is not an equal-risk position.
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 PNR: side by side
| MDY (SPDR S&P MidCap 400 ETF) | PNR (Pentair) | |
|---|---|---|
| 1-year return | +18.3% | -42.5% |
| 5-year return | +47.5% | -14.1% |
| Volatility (ann.) | 16.5% | 28.2% |
| Beta vs S&P 500 | 0.91 | 1.07 |
| Max drawdown (3Y) | -24.0% | -45.0% |
| Market cap | – | $9.9B |
| P/E (trailing) | – | 16.2 |
| Dividend yield | 1.02% | 1.65% |
| Expense ratio | 0.23% | – |
| Assets under management | $26.5B | – |
| Sector / category | ETF · US Small & Mid Cap | Industrials |
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 | PNR |
|---|---|---|
| 2022 | -13.3% | -37.4% |
| 2023 | +16.1% | +64.2% |
| 2024 | +13.6% | +40.0% |
| 2025 | +7.2% | +4.5% |
| 2026 | +16.4% | -39.8% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are MDY and PNR good diversifiers for each other?
Only partially. A correlation of 0.63 means MDY and PNR 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 MDY and PNR?
The MDY/PNR correlation stands at 0.63 on a 3-year window (1 year: 0.29, 5 years: 0.69), computed from weekly returns as of 2026-08-27.
Is PNR a good diversifier for MDY?
Only partially. A correlation of 0.63 means MDY and PNR share most of their swings. Pairing them dampens volatility somewhat, but it will not protect against a common drawdown.
What does a correlation of 0.63 mean?
A reading of 0.63 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-pnr.json
Drop this badge in a README or notebook; it updates with the data:
[](https://www.pairbook.io/pair/mdy-vs-pnr/)
No key needed, free to use. Full endpoint list in the API documentation.
Related comparisons
Hubs: MDY correlations · PNR correlations
