ERII vs QQQ: Correlation
How closely do Energy Recovery, Inc. (ERII) and Invesco QQQ Trust (QQQ) trade together? Their weekly returns over three years give a correlation of 0.35, which is moderate.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are ERII and QQQ?
Over the past 3 years, ERII and QQQ moved with a correlation of 0.35, which is moderate. The link has loosened recently: the 1-year correlation (0.21) runs below the 3-year figure (0.35). Over 5 years the correlation is 0.44, and the annualized covariance of weekly returns is 354.0 %².
Out of 11 assets tracked against ERII, QQQ lands near the bottom at #8. Their recent paths diverged sharply: over the last 12 months QQQ outperformed by 72.1 percentage points (-45.8% for ERII against +26.3% for QQQ). One caveat on sizing: ERII is 2.6 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.
ERII vs QQQ: side by side
| ERII (Energy Recovery, Inc.) | QQQ (Invesco QQQ Trust) | |
|---|---|---|
| 1-year return | -45.8% | +26.3% |
| 5-year return | -60.7% | +95.4% |
| Volatility (ann.) | 51.2% | 19.6% |
| Beta vs S&P 500 | 1.44 | 1.28 |
| Max drawdown (3Y) | -72.4% | -22.8% |
| Market cap | $0.4B | – |
| P/E (trailing) | 30.4 | – |
| Dividend yield | 0.00% | 0.44% |
| Expense ratio | – | 0.18% |
| Assets under management | – | $452.8B |
| Sector / category | US Listed | ETF · US Growth & Tech |
QQQ is a Large Growth fund from Invesco: $452.8B under management, 104 holdings, a 0.18% expense ratio, a 0.44% trailing dividend yield.
Year-by-year returns
| Year | ERII | QQQ |
|---|---|---|
| 2022 | -4.7% | -32.6% |
| 2023 | -8.1% | +54.9% |
| 2024 | -22.0% | +25.6% |
| 2025 | -8.2% | +20.8% |
| 2026 | -41.4% | +17.7% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are ERII and QQQ good diversifiers for each other?
Reasonably. At 0.35, ERII and QQQ keep a meaningful degree of independence, and combining them has historically reduced portfolio volatility.
FAQ
What is the correlation between ERII and QQQ?
The ERII/QQQ correlation stands at 0.35 on a 3-year window (1 year: 0.21, 5 years: 0.44), computed from weekly returns as of 2026-08-27.
Is QQQ a good diversifier for ERII?
Reasonably. At 0.35, ERII and QQQ keep a meaningful degree of independence, and combining them has historically reduced portfolio volatility.
What does a correlation of 0.35 mean?
A reading of 0.35 sits on a scale from −1 (opposite moves) through 0 (unrelated) to +1 (identical moves). Correlation captures direction, not magnitude or performance.
Use this data
$ curl https://www.pairbook.io/api/v1/pairs/erii-vs-qqq.json
Embed this badge (it refreshes with the data), with attribution:
[](https://www.pairbook.io/pair/erii-vs-qqq/)
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Related comparisons
Hubs: ERII correlations · QQQ correlations
