MDY vs MTD: Correlation
How closely do SPDR S&P MidCap 400 ETF (MDY) and Mettler Toledo (MTD) trade together? Their weekly returns over three years give a correlation of 0.56, which is moderate.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are MDY and MTD?
Across a 3-year window, the weekly returns of MDY and MTD correlate at 0.56, moderate. Lately the two have drifted apart, with the 1-year correlation at 0.44 versus 0.56 over 3 years. Stretching to 5 years gives 0.64, with an annualized covariance of 288.5 %².
Within MDY's tracked universe of 359 assets, MTD comes in at #236 by 3-year correlation. Over the last 12 months MDY came out ahead by 8.8 percentage points (+18.3% against +9.5%). Across three years, the rolling one-year figure varied moderately, from 0.41 to 0.79. Risk is not evenly split, since MTD carries 1.9 times the volatility of the other side.
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 MTD: side by side
| MDY (SPDR S&P MidCap 400 ETF) | MTD (Mettler Toledo) | |
|---|---|---|
| 1-year return | +18.3% | +9.5% |
| 5-year return | +47.5% | -11.4% |
| Volatility (ann.) | 16.5% | 31.4% |
| Beta vs S&P 500 | 0.91 | 1.00 |
| Max drawdown (3Y) | -24.0% | -36.6% |
| Market cap | – | $28.2B |
| P/E (trailing) | – | 31.7 |
| Dividend yield | 1.02% | 0.00% |
| Expense ratio | 0.23% | – |
| Assets under management | $26.5B | – |
| Sector / category | ETF · US Small & Mid Cap | Health Care |
MDY is a Mid-Cap Blend fund from State Street Investment Management: $26.5B under management, 400 holdings, a 0.23% expense ratio, a 1.02% trailing dividend yield.
Year-by-year returns
| Year | MDY | MTD |
|---|---|---|
| 2022 | -13.3% | -14.8% |
| 2023 | +16.1% | -16.1% |
| 2024 | +13.6% | +0.9% |
| 2025 | +7.2% | +13.9% |
| 2026 | +16.4% | +0.9% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are MDY and MTD good diversifiers for each other?
Only partially. A correlation of 0.56 means MDY and MTD 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 MTD?
The MDY/MTD correlation stands at 0.56 on a 3-year window (1 year: 0.44, 5 years: 0.64), computed from weekly returns as of 2026-08-27.
Is MTD a good diversifier for MDY?
Only partially. A correlation of 0.56 means MDY and MTD share most of their swings. Pairing them dampens volatility somewhat, but it will not protect against a common drawdown.
What does a correlation of 0.56 mean?
A reading of 0.56 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-mtd.json
Embed this badge (it refreshes with the data), with attribution:
[](https://www.pairbook.io/pair/mdy-vs-mtd/)
The core API is free. Terms and every endpoint in the API documentation.
Related comparisons
Hubs: MDY correlations · MTD correlations
