PETS vs SPY: Correlation
PetMed Express, Inc. (PETS) and SPDR S&P 500 ETF Trust (SPY) show a weak relationship: their 3-year correlation of weekly returns is 0.22.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are PETS and SPY?
Across a 3-year window, the weekly returns of PETS and SPY correlate at 0.22, weak. Little has changed lately, as the 1-year reading of 0.15 lands near the 3-year figure. Stretching to 5 years gives 0.24, with an annualized covariance of 228.9 %².
SPY is close to the least connected end of PETS's tracked universe, ranking #6 of 10. Their recent paths diverged sharply: over the last 12 months SPY outperformed by 62.1 percentage points (-41.5% for PETS against +20.6% for SPY). Note the risk asymmetry: PETS runs 5.0 times the annualized volatility of the other leg, so equal-weighting the two is not an equal-risk position.
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.
PETS vs SPY: side by side
| PETS (PetMed Express, Inc.) | SPY (SPDR S&P 500 ETF Trust) | |
|---|---|---|
| 1-year return | -41.5% | +20.6% |
| 5-year return | -92.7% | +82.4% |
| Volatility (ann.) | 72.9% | 14.5% |
| Beta vs S&P 500 | 1.10 | 1.00 |
| Max drawdown (3Y) | -86.3% | -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 | PETS | SPY |
|---|---|---|
| 2022 | -25.8% | -18.2% |
| 2023 | -54.8% | +26.2% |
| 2024 | -36.2% | +24.9% |
| 2025 | -33.6% | +17.7% |
| 2026 | -42.2% | +13.7% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are PETS and SPY good diversifiers for each other?
Reasonably. At 0.22, PETS and SPY keep a meaningful degree of independence, and combining them has historically reduced portfolio volatility.
FAQ
What is the correlation between PETS and SPY?
Using weekly returns as of 2026-08-27: 0.22 over 3 years, with 0.15 over the last year and 0.24 over 5 years.
Is SPY a good diversifier for PETS?
Reasonably. At 0.22, PETS and SPY keep a meaningful degree of independence, and combining them has historically reduced portfolio volatility.
What does a correlation of 0.22 mean?
A reading of 0.22 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: PETS correlations · SPY correlations
