IRWD vs SPY: Correlation
How closely do Ironwood Pharmaceuticals, Inc. (IRWD) and SPDR S&P 500 ETF Trust (SPY) trade together? Their weekly returns over three years give a correlation of 0.13, which is weak.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are IRWD and SPY?
Across a 3-year window, the weekly returns of IRWD and SPY correlate at 0.13, weak. Recent behaviour matches the longer record: 0.17 over 1 year against 0.13 over 3. Stretching to 5 years gives 0.13, with an annualized covariance of 170.1 %².
Out of 10 assets tracked against IRWD, SPY lands near the bottom at #6. Their recent paths diverged sharply: over the last 12 months IRWD outperformed by 215.9 percentage points (+236.5% for IRWD against +20.6% for SPY). One caveat on sizing: IRWD is 6.1 times as volatile as the other leg, so an equal-dollar split is far from equal-risk.
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.
IRWD vs SPY: side by side
| IRWD (Ironwood Pharmaceuticals, Inc.) | SPY (SPDR S&P 500 ETF Trust) | |
|---|---|---|
| 1-year return | +236.5% | +20.6% |
| 5-year return | -68.1% | +82.4% |
| Volatility (ann.) | 88.3% | 14.5% |
| Beta vs S&P 500 | 0.81 | 1.00 |
| Max drawdown (3Y) | -96.3% | -18.8% |
| Market cap | $0.7B | – |
| P/E (trailing) | 5.4 | – |
| 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 | IRWD | SPY |
|---|---|---|
| 2022 | +6.3% | -18.2% |
| 2023 | -7.7% | +26.2% |
| 2024 | -61.3% | +24.9% |
| 2025 | -23.9% | +17.7% |
| 2026 | +25.8% | +13.7% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are IRWD and SPY good diversifiers for each other?
Yes. With a correlation of 0.13, IRWD and SPY have moved largely independently, which makes them a genuinely diversifying pair by historical standards.
FAQ
What is the correlation between IRWD and SPY?
As of 2026-08-27, the correlation of weekly returns between IRWD and SPY is 0.13 over 3 years, 0.17 over 1 year and 0.13 over 5 years.
Is SPY a good diversifier for IRWD?
Yes. With a correlation of 0.13, IRWD and SPY have moved largely independently, which makes them a genuinely diversifying pair by historical standards.
What does a correlation of 0.13 mean?
Correlation ranges from −1 to +1. Values near +1 mean two assets move together, near 0 that they move independently, and negative values that they tend to move in opposite directions. It measures co-movement, not performance.
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Related comparisons
Hubs: IRWD correlations · SPY correlations
