IWM vs STRO: Correlation
iShares Russell 2000 ETF (IWM) and Sutro Biopharma, Inc. (STRO) show a moderate relationship: their 3-year correlation of weekly returns is 0.52.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are IWM and STRO?
Across a 3-year window, the weekly returns of IWM and STRO correlate at 0.52, moderate. Lately the two have drifted apart, with the 1-year correlation at 0.29 versus 0.52 over 3 years. Stretching to 5 years gives 0.45, with an annualized covariance of 1156.5 %².
Within IWM's tracked universe of 320 assets, STRO comes in at #211 by 3-year correlation. The last year tells two different stories: STRO led by 108.4 percentage points, +28.4% for IWM against +136.8% for STRO. Risk is not evenly split, since STRO carries 5.7 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.
IWM vs STRO: side by side
| IWM (iShares Russell 2000 ETF) | STRO (Sutro Biopharma, Inc.) | |
|---|---|---|
| 1-year return | +28.4% | +136.8% |
| 5-year return | +41.5% | -90.2% |
| Volatility (ann.) | 19.8% | 112.5% |
| Beta vs S&P 500 | 1.06 | 3.52 |
| Max drawdown (3Y) | -27.5% | -90.8% |
| Market cap | – | $0.4B |
| P/E (trailing) | – | – |
| Dividend yield | 0.91% | 0.00% |
| Expense ratio | 0.19% | – |
| Assets under management | $80.1B | – |
| Sector / category | ETF · US Small & Mid Cap | US Listed |
On the fund side, IWM sits in the Small Blend category at iShares, with $80.1B under management, 1757 holdings, a 0.19% expense ratio, a 0.91% trailing dividend yield.
Year-by-year returns
| Year | IWM | STRO |
|---|---|---|
| 2022 | -20.5% | -45.7% |
| 2023 | +16.8% | -46.9% |
| 2024 | +11.4% | -57.1% |
| 2025 | +12.7% | -37.1% |
| 2026 | +22.3% | +84.2% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are IWM and STRO good diversifiers for each other?
Somewhat, no more. With 0.52 correlation, most large moves hit both names, and the diversification benefit stays modest.
FAQ
What is the correlation between IWM and STRO?
The IWM/STRO correlation stands at 0.52 on a 3-year window (1 year: 0.29, 5 years: 0.45), computed from weekly returns as of 2026-08-27.
Is STRO a good diversifier for IWM?
Somewhat, no more. With 0.52 correlation, most large moves hit both names, and the diversification benefit stays modest.
What does a correlation of 0.52 mean?
On the −1 to +1 scale, 0.52 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/iwm-vs-stro.json
Drop this badge in a README or notebook; it updates with the data:
[](https://www.pairbook.io/pair/iwm-vs-stro/)
No key needed, free to use. Full endpoint list in the API documentation.
Related comparisons
Hubs: IWM correlations · STRO correlations
