NPK vs SPY: Correlation
Measured on weekly returns over the past three years, National Presto Industries, Inc. (NPK) and SPDR S&P 500 ETF Trust (SPY) carry a correlation of 0.35, a moderate link.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are NPK and SPY?
Over the past 3 years, NPK and SPY moved with a correlation of 0.35, which is moderate. The past 12 months show a weaker link (0.16) than the 3-year average (0.35). Over 5 years the correlation is 0.40, and the annualized covariance of weekly returns is 146.2 %².
SPY is close to the least connected end of NPK's tracked universe, ranking #6 of 10. Correlation aside, the last 12 months split them widely, with NPK ahead by 23.6 points (+44.2% versus +20.6%). Risk is not evenly split, since NPK 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.
NPK vs SPY: side by side
| NPK (National Presto Industries, Inc.) | SPY (SPDR S&P 500 ETF Trust) | |
|---|---|---|
| 1-year return | +44.2% | +20.6% |
| 5-year return | +115.3% | +82.4% |
| Volatility (ann.) | 28.9% | 14.5% |
| Beta vs S&P 500 | 0.70 | 1.00 |
| Max drawdown (3Y) | -23.3% | -18.8% |
| Market cap | $1.1B | – |
| P/E (trailing) | 25.2 | – |
| Dividend yield | 0.66% | 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 | NPK | SPY |
|---|---|---|
| 2022 | -11.8% | -18.2% |
| 2023 | +23.8% | +26.2% |
| 2024 | +29.9% | +24.9% |
| 2025 | +9.6% | +17.7% |
| 2026 | +44.8% | +13.7% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are NPK and SPY good diversifiers for each other?
Reasonably. At 0.35, NPK and SPY keep a meaningful degree of independence, and combining them has historically reduced portfolio volatility.
FAQ
What is the correlation between NPK and SPY?
Using weekly returns as of 2026-08-27: 0.35 over 3 years, with 0.16 over the last year and 0.40 over 5 years.
Is SPY a good diversifier for NPK?
Reasonably. At 0.35, NPK and SPY keep a meaningful degree of independence, and combining them has historically reduced portfolio volatility.
What does a correlation of 0.35 mean?
On the −1 to +1 scale, 0.35 describes how much the two returns move together: +1 is lockstep, 0 is independence, negative values mean opposite directions. It says nothing about which performed better.
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Related comparisons
Hubs: NPK correlations · SPY correlations
