PULM vs SPY: Correlation
Pulmatrix, Inc. (PULM) and SPDR S&P 500 ETF Trust (SPY) show a near-zero relationship: their 3-year correlation of weekly returns is -0.02.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are PULM and SPY?
Across a 3-year window, the weekly returns of PULM and SPY correlate at -0.02, near zero, meaning they move largely independently. The link has tightened recently: the 1-year correlation (0.15) runs above the 3-year figure (-0.02). Stretching to 5 years gives 0.06, with an annualized covariance of -37.1 %².
Within PULM's tracked universe of 37 assets, SPY comes in at #12 by 3-year correlation. Their recent paths diverged sharply: over the last 12 months SPY outperformed by 89.3 percentage points (-68.7% for PULM against +20.6% for SPY). Risk is not evenly split, since PULM carries 10.0 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.
PULM vs SPY: side by side
| PULM (Pulmatrix, Inc.) | SPY (SPDR S&P 500 ETF Trust) | |
|---|---|---|
| 1-year return | -68.7% | +20.6% |
| 5-year return | -90.6% | +82.4% |
| Volatility (ann.) | 144.8% | 14.5% |
| Beta vs S&P 500 | -0.18 | 1.00 |
| Max drawdown (3Y) | -88.1% | -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 | PULM | SPY |
|---|---|---|
| 2022 | -55.7% | -18.2% |
| 2023 | -52.1% | +26.2% |
| 2024 | +275.3% | +24.9% |
| 2025 | -68.1% | +17.7% |
| 2026 | -31.8% | +13.7% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are PULM and SPY good diversifiers for each other?
Yes: at -0.02, the two have gone their own ways historically, which is what genuine diversification looks like.
FAQ
What is the correlation between PULM and SPY?
The PULM/SPY correlation stands at -0.02 on a 3-year window (1 year: 0.15, 5 years: 0.06), computed from weekly returns as of 2026-08-27.
Is SPY a good diversifier for PULM?
Yes: at -0.02, the two have gone their own ways historically, which is what genuine diversification looks like.
What does a correlation of -0.02 mean?
On the −1 to +1 scale, -0.02 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: PULM correlations · SPY correlations
