MDY vs WTS: Correlation
How closely do SPDR S&P MidCap 400 ETF (MDY) and Watts Water Technologies, Inc. (WTS) trade together? Their weekly returns over three years give a correlation of 0.69, which is strong.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are MDY and WTS?
Over the past 3 years, MDY and WTS moved with a correlation of 0.69, which is strong. Little has changed lately, as the 1-year reading of 0.68 lands near the 3-year figure. Over 5 years the correlation is 0.70, and the annualized covariance of weekly returns is 282.2 %².
By 3-year correlation, WTS places #74 of the 359 assets tracked against MDY. The trailing year gives WTS the advantage: +18.3% versus +31.9%, a 13.6-point spread.
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 WTS: side by side
| MDY (SPDR S&P MidCap 400 ETF) | WTS (Watts Water Technologies, Inc.) | |
|---|---|---|
| 1-year return | +18.3% | +31.9% |
| 5-year return | +47.5% | +125.4% |
| Volatility (ann.) | 16.5% | 24.6% |
| Beta vs S&P 500 | 0.91 | 0.89 |
| Max drawdown (3Y) | -24.0% | -19.5% |
| Market cap | – | $12.4B |
| P/E (trailing) | – | 32.5 |
| Dividend yield | 1.02% | 0.58% |
| 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 | WTS |
|---|---|---|
| 2022 | -13.3% | -24.1% |
| 2023 | +16.1% | +43.6% |
| 2024 | +13.6% | -1.6% |
| 2025 | +7.2% | +36.8% |
| 2026 | +16.4% | +35.4% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Fund exposure
WTS represents 0.28% of MDY's portfolio, so part of any move in MDY is WTS itself, and the correlation between them is partly mechanical.
Are MDY and WTS good diversifiers for each other?
To a limited degree. At 0.69 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 WTS?
As of 2026-08-27, the correlation of weekly returns between MDY and WTS is 0.69 over 3 years, 0.68 over 1 year and 0.70 over 5 years.
Is WTS a good diversifier for MDY?
To a limited degree. At 0.69 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 0.69 mean?
A reading of 0.69 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
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Related comparisons
Hubs: MDY correlations · WTS correlations
