MDY vs RUSHB: Correlation
Measured on weekly returns over the past three years, SPDR S&P MidCap 400 ETF (MDY) and Rush Enterprises, Inc. (RUSHB) carry a correlation of 0.65, a strong link.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are MDY and RUSHB?
On 3 years of weekly data the MDY/RUSHB correlation comes out at 0.65, strong. The relationship has been stable: the 1-year correlation (0.61) sits close to the 3-year figure. The 5-year figure is 0.60, and annualized covariance runs at 327.6 %².
Within MDY's tracked universe of 359 assets, RUSHB comes in at #116 by 3-year correlation. The trailing year gives RUSHB the advantage: +18.3% versus +31.6%, a 13.3-point spread. One caveat on sizing: RUSHB is 1.9 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 RUSHB: side by side
| MDY (SPDR S&P MidCap 400 ETF) | RUSHB (Rush Enterprises, Inc.) | |
|---|---|---|
| 1-year return | +18.3% | +31.6% |
| 5-year return | +47.5% | +185.6% |
| Volatility (ann.) | 16.5% | 30.8% |
| Beta vs S&P 500 | 0.91 | 0.88 |
| Max drawdown (3Y) | -24.0% | -28.5% |
| Market cap | – | $9.0B |
| P/E (trailing) | – | 23.1 |
| Dividend yield | 1.02% | 0.99% |
| 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 | RUSHB |
|---|---|---|
| 2022 | -13.3% | +5.9% |
| 2023 | +16.1% | +43.4% |
| 2024 | +13.6% | +4.3% |
| 2025 | +7.2% | +4.8% |
| 2026 | +16.4% | +38.0% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are MDY and RUSHB good diversifiers for each other?
Only partially. A correlation of 0.65 means MDY and RUSHB 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 RUSHB?
The MDY/RUSHB correlation stands at 0.65 on a 3-year window (1 year: 0.61, 5 years: 0.60), computed from weekly returns as of 2026-08-27.
Is RUSHB a good diversifier for MDY?
Only partially. A correlation of 0.65 means MDY and RUSHB share most of their swings. Pairing them dampens volatility somewhat, but it will not protect against a common drawdown.
What does a correlation of 0.65 mean?
A reading of 0.65 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-rushb.json
Drop this badge in a README or notebook; it updates with the data:
[](https://www.pairbook.io/pair/mdy-vs-rushb/)
Free with attribution; caching and terms are described in the API documentation.
Related comparisons
Hubs: MDY correlations · RUSHB correlations
