DIA vs MDY: Correlation & Overlap
How closely do SPDR Dow Jones Industrial Average ETF (DIA) and SPDR S&P MidCap 400 ETF (MDY) trade together? Their weekly returns over three years give a correlation of 0.86, which is very strong. Looking through to holdings, 0% of the two portfolios is the same by weight.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are DIA and MDY?
On 3 years of weekly data the DIA/MDY correlation comes out at 0.86, very strong, meaning they move nearly in lockstep. Little has changed lately, as the 1-year reading of 0.81 lands near the 3-year figure. The 5-year figure is 0.88, and annualized covariance runs at 185.8 %².
By 3-year correlation, MDY places #17 of the 116 assets tracked against DIA. Twelve-month performance is nearly a tie, at +19.2% for DIA and +18.3% for MDY. Stability stands out here, with the rolling one-year correlation confined to 0.80 through 0.92.
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.
DIA vs MDY: side by side
| DIA (SPDR Dow Jones Industrial Average ETF) | MDY (SPDR S&P MidCap 400 ETF) | |
|---|---|---|
| 1-year return | +19.2% | +18.3% |
| 5-year return | +64.8% | +47.5% |
| Volatility (ann.) | 13.0% | 16.5% |
| Beta vs S&P 500 | 0.79 | 0.91 |
| Max drawdown (3Y) | -16.0% | -24.0% |
| Dividend yield | 1.37% | 1.02% |
| Expense ratio | 0.16% | 0.23% |
| Assets under management | $45.2B | $26.5B |
| Sector / category | ETF · US Large Cap | ETF · US Small & Mid Cap |
DIA is a Large Value fund from State Street Investment Management: $45.2B under management, 30 holdings, a 0.16% expense ratio, a 1.37% trailing dividend yield. 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.
Portfolio overlap between DIA and MDY
The two portfolios are largely distinct, with 0 holdings in common adding up to 0% of fund weight. Where correlation shows the co-movement, the overlap shows its source.
Largest positions held only by DIA: GS (11.56%), CAT (9.13%), MSFT (5.51%), AMGN (4.89%), UNH (4.45%). Only by MDY: TWLO (0.95%), P (0.94%), ILMN (0.93%), FTI (0.83%), ATI (0.80%).
Overlap = sum of the smaller of the two weights across common holdings, from issuer disclosures as of 2026-08-26.
Year-by-year returns
| Year | DIA | MDY |
|---|---|---|
| 2022 | -7.0% | -13.3% |
| 2023 | +16.0% | +16.1% |
| 2024 | +14.8% | +13.6% |
| 2025 | +14.7% | +7.2% |
| 2026 | +12.3% | +16.4% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are DIA and MDY good diversifiers for each other?
Not really. At 0.86, the two trade almost as one position, and owning both buys little extra protection.
FAQ
What is the correlation between DIA and MDY?
As of 2026-08-27, the correlation of weekly returns between DIA and MDY is 0.86 over 3 years, 0.81 over 1 year and 0.88 over 5 years.
Is MDY a good diversifier for DIA?
Not really. At 0.86, the two trade almost as one position, and owning both buys little extra protection.
How much do DIA and MDY overlap?
Per the issuers' own portfolio disclosures (2026-08-26), the overlap is 0% by weight over 0 common positions.
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Related comparisons
Hubs: DIA correlations · MDY correlations
