MDY vs RAIL: Correlation
How closely do SPDR S&P MidCap 400 ETF (MDY) and Freightcar America, Inc. (RAIL) trade together? Their weekly returns over three years give a correlation of 0.40, which is moderate.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are MDY and RAIL?
On 3 years of weekly data the MDY/RAIL correlation comes out at 0.40, moderate. Little has changed lately, as the 1-year reading of 0.36 lands near the 3-year figure. The 5-year figure is 0.39, and annualized covariance runs at 496.9 %².
Among the 359 assets we track against MDY, RAIL ranks #344 by 3-year correlation. The last year tells two different stories: MDY led by 34.4 percentage points, +18.3% for MDY against -16.1% for RAIL. One caveat on sizing: RAIL is 4.6 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 RAIL: side by side
| MDY (SPDR S&P MidCap 400 ETF) | RAIL (Freightcar America, Inc.) | |
|---|---|---|
| 1-year return | +18.3% | -16.1% |
| 5-year return | +47.5% | +36.6% |
| Volatility (ann.) | 16.5% | 75.3% |
| Beta vs S&P 500 | 0.91 | 1.84 |
| Max drawdown (3Y) | -24.0% | -71.7% |
| Market cap | – | $0.2B |
| 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 | RAIL |
|---|---|---|
| 2022 | -13.3% | -13.3% |
| 2023 | +16.1% | -15.6% |
| 2024 | +13.6% | +231.9% |
| 2025 | +7.2% | +23.5% |
| 2026 | +16.4% | -34.6% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are MDY and RAIL good diversifiers for each other?
Yes, to a useful degree: a correlation of 0.40 leaves real independence between the two, which historically damped combined volatility.
FAQ
What is the correlation between MDY and RAIL?
The MDY/RAIL correlation stands at 0.40 on a 3-year window (1 year: 0.36, 5 years: 0.39), computed from weekly returns as of 2026-08-27.
Is RAIL a good diversifier for MDY?
Yes, to a useful degree: a correlation of 0.40 leaves real independence between the two, which historically damped combined volatility.
What does a correlation of 0.40 mean?
A reading of 0.40 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-rail.json
Drop this badge in a README or notebook; it updates with the data:
[](https://www.pairbook.io/pair/mdy-vs-rail/)
Free with attribution; caching and terms are described in the API documentation.
Related comparisons
Hubs: MDY correlations · RAIL correlations
