MDY vs RMT: Correlation
Measured on weekly returns over the past three years, SPDR S&P MidCap 400 ETF (MDY) and Royce Micro-Cap Trust, Inc. (RMT) carry a correlation of 0.89, a very strong link.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are MDY and RMT?
On 3 years of weekly data the MDY/RMT correlation comes out at 0.89, very strong, meaning they move nearly in lockstep. Recent behaviour matches the longer record: 0.85 over 1 year against 0.89 over 3. The 5-year figure is 0.91, and annualized covariance runs at 302.3 %².
Within MDY's tracked universe of 359 assets, RMT comes in at #7 by 3-year correlation. Correlation aside, the last 12 months split them widely, with RMT ahead by 30.1 points (+18.3% versus +48.4%).
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 RMT: side by side
| MDY (SPDR S&P MidCap 400 ETF) | RMT (Royce Micro-Cap Trust, Inc.) | |
|---|---|---|
| 1-year return | +18.3% | +48.4% |
| 5-year return | +47.5% | +80.1% |
| Volatility (ann.) | 16.5% | 20.5% |
| Beta vs S&P 500 | 0.91 | 1.09 |
| Max drawdown (3Y) | -24.0% | -26.4% |
| Market cap | – | $0.8B |
| P/E (trailing) | – | 8.5 |
| Dividend yield | 1.02% | 5.57% |
| Expense ratio | 0.23% | – |
| Assets under management | $26.5B | – |
| Sector / category | ETF · US Small & Mid Cap | US Listed |
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 | RMT |
|---|---|---|
| 2022 | -13.3% | -16.8% |
| 2023 | +16.1% | +15.8% |
| 2024 | +13.6% | +14.0% |
| 2025 | +7.2% | +16.1% |
| 2026 | +16.4% | +39.6% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are MDY and RMT good diversifiers for each other?
Not really. At 0.89, the two trade almost as one position, and owning both buys little extra protection.
FAQ
What is the correlation between MDY and RMT?
As of 2026-08-27, the correlation of weekly returns between MDY and RMT is 0.89 over 3 years, 0.85 over 1 year and 0.91 over 5 years.
Is RMT a good diversifier for MDY?
Not really. At 0.89, the two trade almost as one position, and owning both buys little extra protection.
What does a correlation of 0.89 mean?
Correlation ranges from −1 to +1. Values near +1 mean two assets move together, near 0 that they move independently, and negative values that they tend to move in opposite directions. It measures co-movement, not performance.
Use this data
$ curl https://www.pairbook.io/api/v1/pairs/mdy-vs-rmt.json
Markdown for the live badge, attribution link included:
[](https://www.pairbook.io/pair/mdy-vs-rmt/)
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Related comparisons
Hubs: MDY correlations · RMT correlations
