SPY vs STRO: Correlation
SPDR S&P 500 ETF Trust (SPY) and Sutro Biopharma, Inc. (STRO) show a moderate relationship: their 3-year correlation of weekly returns is 0.45.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are SPY and STRO?
On 3 years of weekly data the SPY/STRO correlation comes out at 0.45, moderate. Lately the two have drifted apart, with the 1-year correlation at 0.29 versus 0.45 over 3 years. The 5-year figure is 0.37, and annualized covariance runs at 734.7 %².
Within SPY's tracked universe of 4755 assets, STRO comes in at #743 by 3-year correlation. The last year tells two different stories: STRO led by 116.2 percentage points, +20.6% for SPY against +136.8% for STRO. Note the risk asymmetry: STRO runs 7.8 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.
SPY vs STRO: side by side
| SPY (SPDR S&P 500 ETF Trust) | STRO (Sutro Biopharma, Inc.) | |
|---|---|---|
| 1-year return | +20.6% | +136.8% |
| 5-year return | +82.4% | -90.2% |
| Volatility (ann.) | 14.5% | 112.5% |
| Beta vs S&P 500 | 1.00 | 3.52 |
| Max drawdown (3Y) | -18.8% | -90.8% |
| Market cap | – | $0.4B |
| P/E (trailing) | – | – |
| Dividend yield | 1.01% | 0.00% |
| Expense ratio | 0.09% | – |
| Assets under management | $795.3B | – |
| Sector / category | ETF · US Large Cap | US Listed |
SPY, State Street Investment Management's Large Blend fund, carries $795.3B under management, 504 holdings, a 0.09% expense ratio, a 1.01% trailing dividend yield.
Year-by-year returns
| Year | SPY | STRO |
|---|---|---|
| 2022 | -18.2% | -45.7% |
| 2023 | +26.2% | -46.9% |
| 2024 | +24.9% | -57.1% |
| 2025 | +17.7% | -37.1% |
| 2026 | +13.7% | +84.2% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are SPY and STRO good diversifiers for each other?
A fair diversifier. At 0.45, enough of each asset's movement is its own that the pair has smoothed outcomes historically.
FAQ
What is the correlation between SPY and STRO?
The SPY/STRO correlation stands at 0.45 on a 3-year window (1 year: 0.29, 5 years: 0.37), computed from weekly returns as of 2026-08-27.
Is STRO a good diversifier for SPY?
A fair diversifier. At 0.45, enough of each asset's movement is its own that the pair has smoothed outcomes historically.
What does a correlation of 0.45 mean?
On the −1 to +1 scale, 0.45 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.
Use this data
$ curl https://www.pairbook.io/api/v1/pairs/spy-vs-stro.json
Drop this badge in a README or notebook; it updates with the data:
[](https://www.pairbook.io/pair/spy-vs-stro/)
No key needed, free to use. Full endpoint list in the API documentation.
Related comparisons
Hubs: SPY correlations · STRO correlations
