IWM vs MASS: Correlation
iShares Russell 2000 ETF (IWM) and 908 Devices Inc. (MASS) show a moderate relationship: their 3-year correlation of weekly returns is 0.46.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are IWM and MASS?
Across a 3-year window, the weekly returns of IWM and MASS correlate at 0.46, moderate. Recent behaviour matches the longer record: 0.49 over 1 year against 0.46 over 3. Stretching to 5 years gives 0.49, with an annualized covariance of 761.6 %².
Within IWM's tracked universe of 320 assets, MASS comes in at #270 by 3-year correlation. Their recent paths diverged sharply: over the last 12 months MASS outperformed by 47.8 percentage points (+28.4% for IWM against +76.2% for MASS). One caveat on sizing: MASS is 4.2 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.
IWM vs MASS: side by side
| IWM (iShares Russell 2000 ETF) | MASS (908 Devices Inc.) | |
|---|---|---|
| 1-year return | +28.4% | +76.2% |
| 5-year return | +41.5% | -69.9% |
| Volatility (ann.) | 19.8% | 82.7% |
| Beta vs S&P 500 | 1.06 | 1.55 |
| Max drawdown (3Y) | -27.5% | -84.9% |
| Market cap | – | $0.5B |
| 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 |
IWM, iShares's Small Blend fund, carries $80.1B under management, 1757 holdings, a 0.19% expense ratio, a 0.91% trailing dividend yield.
Year-by-year returns
| Year | IWM | MASS |
|---|---|---|
| 2022 | -20.5% | -70.5% |
| 2023 | +16.8% | +47.2% |
| 2024 | +11.4% | -80.4% |
| 2025 | +12.7% | +138.6% |
| 2026 | +22.3% | +111.4% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are IWM and MASS good diversifiers for each other?
Reasonably. At 0.46, IWM and MASS keep a meaningful degree of independence, and combining them has historically reduced portfolio volatility.
FAQ
What is the correlation between IWM and MASS?
The IWM/MASS correlation stands at 0.46 on a 3-year window (1 year: 0.49, 5 years: 0.49), computed from weekly returns as of 2026-08-27.
Is MASS a good diversifier for IWM?
Reasonably. At 0.46, IWM and MASS keep a meaningful degree of independence, and combining them has historically reduced portfolio volatility.
What does a correlation of 0.46 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.
Use this data
$ curl https://www.pairbook.io/api/v1/pairs/iwm-vs-mass.json
Drop this badge in a README or notebook; it updates with the data:
[](https://www.pairbook.io/pair/iwm-vs-mass/)
Free with attribution; caching and terms are described in the API documentation.
Related comparisons
Hubs: IWM correlations · MASS correlations
