OPTT vs SPY: Correlation
How closely do Ocean Power Technologies, Inc. (OPTT) and SPDR S&P 500 ETF Trust (SPY) trade together? Their weekly returns over three years give a correlation of 0.20, which is weak.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are OPTT and SPY?
On 3 years of weekly data the OPTT/SPY correlation comes out at 0.20, weak. The past 12 months show a tighter link (0.43) than the 3-year average (0.20). The 5-year figure is 0.22, and annualized covariance runs at 518.4 %².
Among the 10 assets we track against OPTT, SPY sits near the bottom by co-movement, at rank #6. Correlation aside, the last 12 months split them widely, with SPY ahead by 87.5 points (-66.9% versus +20.6%). One caveat on sizing: OPTT is 12.2 times as volatile as the other leg, so an equal-dollar split is far from equal-risk.
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.
OPTT vs SPY: side by side
| OPTT (Ocean Power Technologies, Inc.) | SPY (SPDR S&P 500 ETF Trust) | |
|---|---|---|
| 1-year return | -66.9% | +20.6% |
| 5-year return | -91.7% | +82.4% |
| Volatility (ann.) | 176.9% | 14.5% |
| Beta vs S&P 500 | 2.48 | 1.00 |
| Max drawdown (3Y) | -91.3% | -18.8% |
| Market cap | – | – |
| P/E (trailing) | – | – |
| Dividend yield | 0.00% | 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 | OPTT | SPY |
|---|---|---|
| 2022 | -69.6% | -18.2% |
| 2023 | -28.9% | +26.2% |
| 2024 | +218.8% | +24.9% |
| 2025 | -70.6% | +17.7% |
| 2026 | -40.4% | +13.7% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are OPTT and SPY good diversifiers for each other?
Yes, to a useful degree: a correlation of 0.20 leaves real independence between the two, which historically damped combined volatility.
FAQ
What is the correlation between OPTT and SPY?
Using weekly returns as of 2026-08-27: 0.20 over 3 years, with 0.43 over the last year and 0.22 over 5 years.
Is SPY a good diversifier for OPTT?
Yes, to a useful degree: a correlation of 0.20 leaves real independence between the two, which historically damped combined volatility.
What does a correlation of 0.20 mean?
A reading of 0.20 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: OPTT correlations · SPY correlations
