MRTN vs SPY: Correlation
How closely do Marten Transport, Ltd. (MRTN) and SPDR S&P 500 ETF Trust (SPY) trade together? Their weekly returns over three years give a correlation of 0.39, which is moderate.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are MRTN and SPY?
Across a 3-year window, the weekly returns of MRTN and SPY correlate at 0.39, moderate. Lately the two have drifted apart, with the 1-year correlation at 0.17 versus 0.39 over 3 years. Stretching to 5 years gives 0.36, with an annualized covariance of 162.3 %².
Within MRTN's tracked universe of 21 assets, SPY comes in at #16 by 3-year correlation. Neither side won the trailing year by much: +23.4% against +20.6%. Risk is not evenly split, since MRTN carries 2.0 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.
MRTN vs SPY: side by side
| MRTN (Marten Transport, Ltd.) | SPY (SPDR S&P 500 ETF Trust) | |
|---|---|---|
| 1-year return | +23.4% | +20.6% |
| 5-year return | -1.0% | +82.4% |
| Volatility (ann.) | 28.6% | 14.5% |
| Beta vs S&P 500 | 0.78 | 1.00 |
| Max drawdown (3Y) | -54.8% | -18.8% |
| Market cap | $1.2B | – |
| P/E (trailing) | 96.4 | – |
| Dividend yield | 1.66% | 1.01% |
| Expense ratio | – | 0.09% |
| Assets under management | – | $795.3B |
| Sector / category | US Listed | ETF · US Large Cap |
SPY is a Large Blend fund from State Street Investment Management: $795.3B under management, 504 holdings, a 0.09% expense ratio, a 1.01% trailing dividend yield.
Year-by-year returns
| Year | MRTN | SPY |
|---|---|---|
| 2022 | +16.7% | -18.2% |
| 2023 | +7.3% | +26.2% |
| 2024 | -24.6% | +24.9% |
| 2025 | -25.7% | +17.7% |
| 2026 | +28.1% | +13.7% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are MRTN and SPY good diversifiers for each other?
Reasonably. At 0.39, MRTN and SPY keep a meaningful degree of independence, and combining them has historically reduced portfolio volatility.
FAQ
What is the correlation between MRTN and SPY?
The MRTN/SPY correlation stands at 0.39 on a 3-year window (1 year: 0.17, 5 years: 0.36), computed from weekly returns as of 2026-08-27.
Is SPY a good diversifier for MRTN?
Reasonably. At 0.39, MRTN and SPY keep a meaningful degree of independence, and combining them has historically reduced portfolio volatility.
What does a correlation of 0.39 mean?
A reading of 0.39 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: MRTN correlations · SPY correlations
