GWW vs MDY: Correlation
Measured on weekly returns over the past three years, W. W. Grainger (GWW) and SPDR S&P MidCap 400 ETF (MDY) carry a correlation of 0.53, a moderate link.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are GWW and MDY?
Across a 3-year window, the weekly returns of GWW and MDY correlate at 0.53, moderate. The link has loosened recently: the 1-year correlation (0.31) runs below the 3-year figure (0.53). Stretching to 5 years gives 0.59, with an annualized covariance of 204.7 %².
Among the 29 assets we track against GWW, MDY ranks #14 by 3-year correlation. On 12-month performance GWW holds a 12.7-point edge, +31.0% against +18.3%. On a rolling one-year basis the correlation drifted between 0.33 and 0.76, a moderate band.
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.
GWW vs MDY: side by side
| GWW (W. W. Grainger) | MDY (SPDR S&P MidCap 400 ETF) | |
|---|---|---|
| 1-year return | +31.0% | +18.3% |
| 5-year return | +219.4% | +47.5% |
| Volatility (ann.) | 23.3% | 16.5% |
| Beta vs S&P 500 | 0.74 | 0.91 |
| Max drawdown (3Y) | -24.5% | -24.0% |
| Market cap | $62.2B | – |
| P/E (trailing) | 34.0 | – |
| Dividend yield | 0.69% | 1.02% |
| Expense ratio | – | 0.23% |
| Assets under management | – | $26.5B |
| Sector / category | Industrials | ETF · US Small & Mid Cap |
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 | GWW | MDY |
|---|---|---|
| 2022 | +8.7% | -13.3% |
| 2023 | +50.5% | +16.1% |
| 2024 | +28.2% | +13.6% |
| 2025 | -3.4% | +7.2% |
| 2026 | +31.7% | +16.4% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are GWW and MDY good diversifiers for each other?
Only partially. A correlation of 0.53 means GWW and MDY 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 GWW and MDY?
As of 2026-08-27, the correlation of weekly returns between GWW and MDY is 0.53 over 3 years, 0.31 over 1 year and 0.59 over 5 years.
Is MDY a good diversifier for GWW?
Only partially. A correlation of 0.53 means GWW and MDY share most of their swings. Pairing them dampens volatility somewhat, but it will not protect against a common drawdown.
What does a correlation of 0.53 mean?
A reading of 0.53 sits on a scale from −1 (opposite moves) through 0 (unrelated) to +1 (identical moves). Correlation captures direction, not magnitude or performance.
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Related comparisons
Hubs: GWW correlations · MDY correlations
