IEX vs MDY: Correlation
Measured on weekly returns over the past three years, IDEX Corporation (IEX) and SPDR S&P MidCap 400 ETF (MDY) carry a correlation of 0.72, a strong link.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are IEX and MDY?
Over the past 3 years, IEX and MDY moved with a correlation of 0.72, which is strong. Little has changed lately, as the 1-year reading of 0.64 lands near the 3-year figure. Over 5 years the correlation is 0.70, and the annualized covariance of weekly returns is 276.6 %².
Few assets follow IEX as closely as MDY, which ranks #2 of 40 tracked partners. Correlation aside, the last 12 months split them widely, with IEX ahead by 24.7 points (+43.0% versus +18.3%). The link looks structural: the rolling one-year correlation barely moved, holding between 0.63 and 0.79.
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.
IEX vs MDY: side by side
| IEX (IDEX Corporation) | MDY (SPDR S&P MidCap 400 ETF) | |
|---|---|---|
| 1-year return | +43.0% | +18.3% |
| 5-year return | +10.5% | +47.5% |
| Volatility (ann.) | 23.3% | 16.5% |
| Beta vs S&P 500 | 0.89 | 0.91 |
| Max drawdown (3Y) | -34.6% | -24.0% |
| Market cap | $17.2B | – |
| P/E (trailing) | 33.8 | – |
| Dividend yield | 1.23% | 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 | IEX | MDY |
|---|---|---|
| 2022 | -2.2% | -13.3% |
| 2023 | -3.8% | +16.1% |
| 2024 | -2.4% | +13.6% |
| 2025 | -13.7% | +7.2% |
| 2026 | +32.9% | +16.4% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are IEX and MDY good diversifiers for each other?
Only partially. A correlation of 0.72 means IEX 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 IEX and MDY?
As of 2026-08-27, the correlation of weekly returns between IEX and MDY is 0.72 over 3 years, 0.64 over 1 year and 0.70 over 5 years.
Is MDY a good diversifier for IEX?
Only partially. A correlation of 0.72 means IEX 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 0.72 mean?
A reading of 0.72 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: IEX correlations · MDY correlations
