MDY vs MSA: Correlation
SPDR S&P MidCap 400 ETF (MDY) and MSA Safety Incorporated (MSA) show a strong relationship: their 3-year correlation of weekly returns is 0.62.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are MDY and MSA?
On 3 years of weekly data the MDY/MSA correlation comes out at 0.62, strong. The past 12 months show a weaker link (0.49) than the 3-year average (0.62). The 5-year figure is 0.65, and annualized covariance runs at 241.3 %².
By 3-year correlation, MSA places #151 of the 359 assets tracked against MDY. The trailing year gives MDY the advantage: +18.3% versus +11.4%, a 6.9-point spread.
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 MSA: side by side
| MDY (SPDR S&P MidCap 400 ETF) | MSA (MSA Safety Incorporated) | |
|---|---|---|
| 1-year return | +18.3% | +11.4% |
| 5-year return | +47.5% | +27.9% |
| Volatility (ann.) | 16.5% | 23.4% |
| Beta vs S&P 500 | 0.91 | 0.85 |
| Max drawdown (3Y) | -24.0% | -34.3% |
| Market cap | – | $7.4B |
| P/E (trailing) | – | 23.7 |
| Dividend yield | 1.02% | 1.12% |
| Expense ratio | 0.23% | – |
| Assets under management | $26.5B | – |
| Sector / category | ETF · US Small & Mid Cap | US Listed |
MDY is a Mid-Cap Blend fund from State Street Investment Management: $26.5B under management, 400 holdings, a 0.23% expense ratio, a 1.02% trailing dividend yield.
Year-by-year returns
| Year | MDY | MSA |
|---|---|---|
| 2022 | -13.3% | -3.1% |
| 2023 | +16.1% | +18.5% |
| 2024 | +13.6% | -0.7% |
| 2025 | +7.2% | -2.1% |
| 2026 | +16.4% | +20.7% |
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 MSA at a 0.19% weight, which makes a slice of this correlation mechanical rather than coincidental.
Are MDY and MSA good diversifiers for each other?
To a limited degree. At 0.62 the two still catch most of the same waves, so the pair smooths returns a little without insulating either from a shared selloff.
FAQ
What is the correlation between MDY and MSA?
As of 2026-08-27, the correlation of weekly returns between MDY and MSA is 0.62 over 3 years, 0.49 over 1 year and 0.65 over 5 years.
Is MSA a good diversifier for MDY?
To a limited degree. At 0.62 the two still catch most of the same waves, so the pair smooths returns a little without insulating either from a shared selloff.
What does a correlation of 0.62 mean?
Correlation ranges from −1 to +1. Values near +1 mean two assets move together, near 0 that they move independently, and negative values that they tend to move in opposite directions. It measures co-movement, not performance.
Use this data
$ curl https://www.pairbook.io/api/v1/pairs/mdy-vs-msa.json
Embed this badge (it refreshes with the data), with attribution:
[](https://www.pairbook.io/pair/mdy-vs-msa/)
No key needed, free to use. Full endpoint list in the API documentation.
Related comparisons
Hubs: MDY correlations · MSA correlations
