MDY vs NPO: Correlation
Measured on weekly returns over the past three years, SPDR S&P MidCap 400 ETF (MDY) and Enpro Inc. (NPO) carry a correlation of 0.69, a strong link.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are MDY and NPO?
Over the past 3 years, MDY and NPO moved with a correlation of 0.69, which is strong. The past 12 months show a weaker link (0.56) than the 3-year average (0.69). Over 5 years the correlation is 0.68, and the annualized covariance of weekly returns is 392.8 %².
Within MDY's tracked universe of 359 assets, NPO comes in at #70 by 3-year correlation. Their recent paths diverged sharply: over the last 12 months NPO outperformed by 18.8 percentage points (+18.3% for MDY against +37.1% for NPO). One caveat on sizing: NPO is 2.1 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 NPO: side by side
| MDY (SPDR S&P MidCap 400 ETF) | NPO (Enpro Inc.) | |
|---|---|---|
| 1-year return | +18.3% | +37.1% |
| 5-year return | +47.5% | +270.5% |
| Volatility (ann.) | 16.5% | 34.4% |
| Beta vs S&P 500 | 0.91 | 1.27 |
| Max drawdown (3Y) | -24.0% | -33.7% |
| Market cap | – | $6.5B |
| P/E (trailing) | – | 149.1 |
| Dividend yield | 1.02% | 0.41% |
| 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 | NPO |
|---|---|---|
| 2022 | -13.3% | -0.2% |
| 2023 | +16.1% | +45.6% |
| 2024 | +13.6% | +10.9% |
| 2025 | +7.2% | +25.0% |
| 2026 | +16.4% | +44.5% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are MDY and NPO good diversifiers for each other?
Only partially. A correlation of 0.69 means MDY and NPO 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 NPO?
The MDY/NPO correlation stands at 0.69 on a 3-year window (1 year: 0.56, 5 years: 0.68), computed from weekly returns as of 2026-08-27.
Is NPO a good diversifier for MDY?
Only partially. A correlation of 0.69 means MDY and NPO share most of their swings. Pairing them dampens volatility somewhat, but it will not protect against a common drawdown.
What does a correlation of 0.69 mean?
A reading of 0.69 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-npo.json
Embed this badge (it refreshes with the data), with attribution:
[](https://www.pairbook.io/pair/mdy-vs-npo/)
No key needed, free to use. Full endpoint list in the API documentation.
Related comparisons
Hubs: MDY correlations · NPO correlations
