MDY vs WCC: Correlation
How closely do SPDR S&P MidCap 400 ETF (MDY) and WESCO International, Inc. (WCC) trade together? Their weekly returns over three years give a correlation of 0.65, which is strong.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are MDY and WCC?
On 3 years of weekly data the MDY/WCC correlation comes out at 0.65, strong. The past 12 months show a weaker link (0.44) than the 3-year average (0.65). The 5-year figure is 0.70, and annualized covariance runs at 408.9 %².
Among the 359 assets we track against MDY, WCC ranks #120 by 3-year correlation. Their recent paths diverged sharply: over the last 12 months WCC outperformed by 37.1 percentage points (+18.3% for MDY against +55.4% for WCC). Note the risk asymmetry: WCC runs 2.3 times the annualized volatility of the other leg, so equal-weighting the two is not an equal-risk position.
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 WCC: side by side
| MDY (SPDR S&P MidCap 400 ETF) | WCC (WESCO International, Inc.) | |
|---|---|---|
| 1-year return | +18.3% | +55.4% |
| 5-year return | +47.5% | +203.7% |
| Volatility (ann.) | 16.5% | 38.3% |
| Beta vs S&P 500 | 0.91 | 1.59 |
| Max drawdown (3Y) | -24.0% | -37.4% |
| Market cap | – | $17.1B |
| P/E (trailing) | – | 24.0 |
| Dividend yield | 1.02% | 0.55% |
| 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 | WCC |
|---|---|---|
| 2022 | -13.3% | -4.9% |
| 2023 | +16.1% | +40.2% |
| 2024 | +13.6% | +5.1% |
| 2025 | +7.2% | +36.4% |
| 2026 | +16.4% | +43.8% |
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 WCC at a 0.46% weight, which makes a slice of this correlation mechanical rather than coincidental.
Are MDY and WCC good diversifiers for each other?
To a limited degree. At 0.65 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 WCC?
Using weekly returns as of 2026-08-27: 0.65 over 3 years, with 0.44 over the last year and 0.70 over 5 years.
Is WCC a good diversifier for MDY?
To a limited degree. At 0.65 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 0.65 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-wcc.json
Markdown for the live badge, attribution link included:
[](https://www.pairbook.io/pair/mdy-vs-wcc/)
No key needed, free to use. Full endpoint list in the API documentation.
Related comparisons
Hubs: MDY correlations · WCC correlations
