MDY vs PRM: Correlation
How closely do SPDR S&P MidCap 400 ETF (MDY) and Perimeter Solutions, SA (PRM) trade together? Their weekly returns over three years give a correlation of 0.49, which is moderate.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are MDY and PRM?
On 3 years of weekly data the MDY/PRM correlation comes out at 0.49, moderate. Recent behaviour matches the longer record: 0.48 over 1 year against 0.49 over 3. The 5-year figure is 0.51, and annualized covariance runs at 396.5 %².
Within MDY's tracked universe of 359 assets, PRM comes in at #307 by 3-year correlation. Correlation aside, the last 12 months split them widely, with PRM ahead by 28.6 points (+18.3% versus +46.9%). Risk is not evenly split, since PRM carries 3.0 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 PRM: side by side
| MDY (SPDR S&P MidCap 400 ETF) | PRM (Perimeter Solutions, SA) | |
|---|---|---|
| 1-year return | +18.3% | +46.9% |
| 5-year return | +47.5% | +166.9% |
| Volatility (ann.) | 16.5% | 49.1% |
| Beta vs S&P 500 | 0.91 | 1.44 |
| Max drawdown (3Y) | -24.0% | -51.3% |
| Market cap | – | $5.2B |
| 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 | PRM |
|---|---|---|
| 2022 | -13.3% | -34.2% |
| 2023 | +16.1% | -49.7% |
| 2024 | +13.6% | +177.8% |
| 2025 | +7.2% | +115.4% |
| 2026 | +16.4% | +16.3% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are MDY and PRM good diversifiers for each other?
Reasonably. At 0.49, MDY and PRM keep a meaningful degree of independence, and combining them has historically reduced portfolio volatility.
FAQ
What is the correlation between MDY and PRM?
Using weekly returns as of 2026-08-27: 0.49 over 3 years, with 0.48 over the last year and 0.51 over 5 years.
Is PRM a good diversifier for MDY?
Reasonably. At 0.49, MDY and PRM keep a meaningful degree of independence, and combining them has historically reduced portfolio volatility.
What does a correlation of 0.49 mean?
On the −1 to +1 scale, 0.49 describes how much the two returns move together: +1 is lockstep, 0 is independence, negative values mean opposite directions. It says nothing about which performed better.
Use this data
$ curl https://www.pairbook.io/api/v1/pairs/mdy-vs-prm.json
Drop this badge in a README or notebook; it updates with the data:
[](https://www.pairbook.io/pair/mdy-vs-prm/)
No key needed, free to use. Full endpoint list in the API documentation.
Related comparisons
Hubs: MDY correlations · PRM correlations
