NSSC vs SPY: Correlation
How closely do NAPCO Security Technologies, Inc. (NSSC) and SPDR S&P 500 ETF Trust (SPY) trade together? Their weekly returns over three years give a correlation of 0.41, which is moderate.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are NSSC and SPY?
Across a 3-year window, the weekly returns of NSSC and SPY correlate at 0.41, moderate. The relationship has been stable: the 1-year correlation (0.40) sits close to the 3-year figure. Stretching to 5 years gives 0.40, with an annualized covariance of 304.4 %².
By 3-year correlation, SPY places #7 of the 14 assets tracked against NSSC. Correlation aside, the last 12 months split them widely, with SPY ahead by 27.4 points (-6.8% versus +20.6%). Note the risk asymmetry: NSSC runs 3.5 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.
NSSC vs SPY: side by side
| NSSC (NAPCO Security Technologies, Inc.) | SPY (SPDR S&P 500 ETF Trust) | |
|---|---|---|
| 1-year return | -6.8% | +20.6% |
| 5-year return | +91.1% | +82.4% |
| Volatility (ann.) | 51.3% | 14.5% |
| Beta vs S&P 500 | 1.46 | 1.00 |
| Max drawdown (3Y) | -65.4% | -18.8% |
| Market cap | $1.3B | – |
| P/E (trailing) | 29.6 | – |
| Dividend yield | 1.62% | 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 | NSSC | SPY |
|---|---|---|
| 2022 | +10.0% | -18.2% |
| 2023 | +25.6% | +26.2% |
| 2024 | +5.0% | +24.9% |
| 2025 | +19.2% | +17.7% |
| 2026 | -14.7% | +13.7% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are NSSC and SPY good diversifiers for each other?
Yes, to a useful degree: a correlation of 0.41 leaves real independence between the two, which historically damped combined volatility.
FAQ
What is the correlation between NSSC and SPY?
The NSSC/SPY correlation stands at 0.41 on a 3-year window (1 year: 0.40, 5 years: 0.40), computed from weekly returns as of 2026-08-27.
Is SPY a good diversifier for NSSC?
Yes, to a useful degree: a correlation of 0.41 leaves real independence between the two, which historically damped combined volatility.
What does a correlation of 0.41 mean?
On the −1 to +1 scale, 0.41 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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Hubs: NSSC correlations · SPY correlations
