MDY vs RSP: Correlation & Overlap
How closely do SPDR S&P MidCap 400 ETF (MDY) and Invesco S&P 500 Equal Weight ETF (RSP) trade together? Their weekly returns over three years give a correlation of 0.95, which is very strong. By holdings, the two funds overlap 0% by weight.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are MDY and RSP?
Across a 3-year window, the weekly returns of MDY and RSP correlate at 0.95, very strong, meaning they move nearly in lockstep. Little has changed lately, as the 1-year reading of 0.89 lands near the 3-year figure. Stretching to 5 years gives 0.96, with an annualized covariance of 206.5 %².
RSP is one of the assets that tracks MDY most closely: it ranks #2 out of the 359 assets we track against MDY. Twelve-month performance is nearly a tie, at +18.3% for MDY and +19.2% for RSP. Stability stands out here, with the rolling one-year correlation confined to 0.90 through 0.97.
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 RSP: side by side
| MDY (SPDR S&P MidCap 400 ETF) | RSP (Invesco S&P 500 Equal Weight ETF) | |
|---|---|---|
| 1-year return | +18.3% | +19.2% |
| 5-year return | +47.5% | +53.9% |
| Volatility (ann.) | 16.5% | 13.2% |
| Beta vs S&P 500 | 0.91 | 0.77 |
| Max drawdown (3Y) | -24.0% | -17.8% |
| Dividend yield | 1.02% | 1.49% |
| Expense ratio | 0.23% | 0.20% |
| Assets under management | $26.5B | $97.3B |
| Sector / category | ETF · US Small & Mid Cap | ETF · US Large Cap |
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. On the fund side, RSP sits in the Large Blend category at Invesco, with $97.3B under management, 505 holdings, a 0.20% expense ratio, a 1.49% trailing dividend yield.
Portfolio overlap between MDY and RSP
The two portfolios are largely distinct. Weighing the shared positions, 0% of the two funds is identical, spread across 0 common holdings. That shared book is a large part of why the returns line up.
Largest positions held only by MDY: TWLO (0.95%), P (0.94%), ILMN (0.93%), FTI (0.83%), ATI (0.80%). Only by RSP: MRNA (0.61%), ZBRA (0.31%), CRL (0.29%), DASH (0.29%), EXPE (0.28%).
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 | MDY | RSP |
|---|---|---|
| 2022 | -13.3% | -11.6% |
| 2023 | +16.1% | +13.7% |
| 2024 | +13.6% | +12.8% |
| 2025 | +7.2% | +11.2% |
| 2026 | +16.4% | +16.5% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are MDY and RSP good diversifiers for each other?
No: a correlation of 0.95 means MDY and RSP tend to fall together, which is precisely when diversification is supposed to help.
FAQ
What is the correlation between MDY and RSP?
Using weekly returns as of 2026-08-27: 0.95 over 3 years, with 0.89 over the last year and 0.96 over 5 years.
Is RSP a good diversifier for MDY?
No: a correlation of 0.95 means MDY and RSP tend to fall together, which is precisely when diversification is supposed to help.
How much do MDY and RSP overlap?
0% by weight, across 0 common holdings, based on issuer-disclosed portfolios as of 2026-08-26.
Use this data
$ curl https://www.pairbook.io/api/v1/pairs/mdy-vs-rsp.json
Embed this badge (it refreshes with the data), with attribution:
[](https://www.pairbook.io/pair/mdy-vs-rsp/)
No key needed, free to use. Full endpoint list in the API documentation.
Related comparisons
Hubs: MDY correlations · RSP correlations
