MDY vs WSC: Correlation
How closely do SPDR S&P MidCap 400 ETF (MDY) and WillScot Holdings Corporation (WSC) trade together? Their weekly returns over three years give a correlation of 0.63, which is strong.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are MDY and WSC?
Across a 3-year window, the weekly returns of MDY and WSC correlate at 0.63, strong. The relationship has been stable: the 1-year correlation (0.64) sits close to the 3-year figure. Stretching to 5 years gives 0.62, with an annualized covariance of 479.1 %².
Within MDY's tracked universe of 359 assets, WSC comes in at #142 by 3-year correlation. The last year tells two different stories: MDY led by 33.2 percentage points, +18.3% for MDY against -14.9% for WSC. One caveat on sizing: WSC is 2.8 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 WSC: side by side
| MDY (SPDR S&P MidCap 400 ETF) | WSC (WillScot Holdings Corporation) | |
|---|---|---|
| 1-year return | +18.3% | -14.9% |
| 5-year return | +47.5% | -27.7% |
| Volatility (ann.) | 16.5% | 45.9% |
| Beta vs S&P 500 | 0.91 | 1.72 |
| Max drawdown (3Y) | -24.0% | -70.7% |
| Market cap | – | $3.8B |
| P/E (trailing) | – | – |
| Dividend yield | 1.02% | 1.31% |
| Expense ratio | 0.23% | – |
| Assets under management | $26.5B | – |
| Sector / category | ETF · US Small & Mid Cap | US Listed |
On the fund side, MDY sits in the Mid-Cap Blend category at State Street Investment Management, with $26.5B under management, 400 holdings, a 0.23% expense ratio, a 1.02% trailing dividend yield.
Year-by-year returns
| Year | MDY | WSC |
|---|---|---|
| 2022 | -13.3% | +10.6% |
| 2023 | +16.1% | -1.5% |
| 2024 | +13.6% | -24.8% |
| 2025 | +7.2% | -43.1% |
| 2026 | +16.4% | +11.9% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are MDY and WSC good diversifiers for each other?
Only partially. A correlation of 0.63 means MDY and WSC 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 WSC?
The MDY/WSC correlation stands at 0.63 on a 3-year window (1 year: 0.64, 5 years: 0.62), computed from weekly returns as of 2026-08-27.
Is WSC a good diversifier for MDY?
Only partially. A correlation of 0.63 means MDY and WSC share most of their swings. Pairing them dampens volatility somewhat, but it will not protect against a common drawdown.
What does a correlation of 0.63 mean?
On the −1 to +1 scale, 0.63 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-wsc.json
Markdown for the live badge, attribution link included:
[](https://www.pairbook.io/pair/mdy-vs-wsc/)
The core API is free. Terms and every endpoint in the API documentation.
Related comparisons
Hubs: MDY correlations · WSC correlations
