BOLD vs SPY: Correlation
Boundless Bio, Inc. (BOLD) and SPDR S&P 500 ETF Trust (SPY) show a weak relationship: their 3-year correlation of weekly returns is 0.25.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are BOLD and SPY?
On 3 years of weekly data the BOLD/SPY correlation comes out at 0.25, weak. Lately the two have drifted apart, with the 1-year correlation at 0.05 versus 0.25 over 3 years. The 5-year figure is n/a, and annualized covariance runs at 334.2 %².
Among the 18 assets we track against BOLD, SPY sits near the bottom by co-movement, at rank #14. The last year tells two different stories: BOLD led by 130.3 percentage points, +150.9% for BOLD against +20.6% for SPY. Note the risk asymmetry: BOLD runs 6.3 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.
BOLD vs SPY: side by side
| BOLD (Boundless Bio, Inc.) | SPY (SPDR S&P 500 ETF Trust) | |
|---|---|---|
| 1-year return | +150.9% | +20.6% |
| 5-year return | n/a | +82.4% |
| Volatility (ann.) | 90.9% | 14.5% |
| Beta vs S&P 500 | 1.60 | 1.00 |
| Max drawdown (3Y) | -92.9% | -18.8% |
| Market cap | $0.1B | – |
| 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 | BOLD | SPY |
|---|---|---|
| 2022 | – | -18.2% |
| 2023 | – | +26.2% |
| 2024 | – | +24.9% |
| 2025 | -58.6% | +17.7% |
| 2026 | +138.3% | +13.7% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are BOLD and SPY good diversifiers for each other?
Yes, to a useful degree: a correlation of 0.25 leaves real independence between the two, which historically damped combined volatility.
FAQ
What is the correlation between BOLD and SPY?
The BOLD/SPY correlation stands at 0.25 on a 3-year window (1 year: 0.05, 5 years: n/a), computed from weekly returns as of 2026-08-27.
Is SPY a good diversifier for BOLD?
Yes, to a useful degree: a correlation of 0.25 leaves real independence between the two, which historically damped combined volatility.
What does a correlation of 0.25 mean?
A reading of 0.25 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: BOLD correlations · SPY correlations
