IRON vs SPY: Correlation
Measured on weekly returns over the past three years, Disc Medicine, Inc. (IRON) and SPDR S&P 500 ETF Trust (SPY) carry a correlation of 0.41, a moderate link.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are IRON and SPY?
On 3 years of weekly data the IRON/SPY correlation comes out at 0.41, moderate. The past 12 months show a weaker link (0.28) than the 3-year average (0.41). The 5-year figure is 0.25, and annualized covariance runs at 355.0 %².
Among the 15 assets we track against IRON, SPY ranks #6 by 3-year correlation. The last year tells two different stories: IRON led by 17.1 percentage points, +37.7% for IRON against +20.6% for SPY. Risk is not evenly split, since IRON carries 4.1 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.
IRON vs SPY: side by side
| IRON (Disc Medicine, Inc.) | SPY (SPDR S&P 500 ETF Trust) | |
|---|---|---|
| 1-year return | +37.7% | +20.6% |
| 5-year return | -32.4% | +82.4% |
| Volatility (ann.) | 59.7% | 14.5% |
| Beta vs S&P 500 | 1.70 | 1.00 |
| Max drawdown (3Y) | -64.8% | -18.8% |
| Market cap | $3.2B | – |
| 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 | IRON | SPY |
|---|---|---|
| 2022 | -77.2% | -18.2% |
| 2023 | +190.4% | +26.2% |
| 2024 | +9.8% | +24.9% |
| 2025 | +25.3% | +17.7% |
| 2026 | +4.0% | +13.7% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are IRON and SPY good diversifiers for each other?
A fair diversifier. At 0.41, enough of each asset's movement is its own that the pair has smoothed outcomes historically.
FAQ
What is the correlation between IRON and SPY?
As of 2026-08-27, the correlation of weekly returns between IRON and SPY is 0.41 over 3 years, 0.28 over 1 year and 0.25 over 5 years.
Is SPY a good diversifier for IRON?
A fair diversifier. At 0.41, enough of each asset's movement is its own that the pair has smoothed outcomes historically.
What does a correlation of 0.41 mean?
A reading of 0.41 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: IRON correlations · SPY correlations
