FCEL vs NBBK: Correlation
Measured on weekly returns over the past three years, FuelCell Energy, Inc. (FCEL) and NB Bancorp, Inc. (NBBK) carry a correlation of -0.22, a negative link.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are FCEL and NBBK?
Across a 3-year window, the weekly returns of FCEL and NBBK correlate at -0.22, negative, meaning they tend to move in opposite directions. The past 12 months show a weaker link (-0.34) than the 3-year average (-0.22). Stretching to 5 years gives n/a, with an annualized covariance of -666.1 %².
NBBK is close to the least connected end of FCEL's tracked universe, ranking #9 of 11. Correlation aside, the last 12 months split them widely, with FCEL ahead by 323.8 points (+343.1% versus +19.3%). Note the risk asymmetry: FCEL runs 4.0 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.
FCEL vs NBBK: side by side
| FCEL (FuelCell Energy, Inc.) | NBBK (NB Bancorp, Inc.) | |
|---|---|---|
| 1-year return | +343.1% | +19.3% |
| 5-year return | -89.6% | n/a |
| Volatility (ann.) | 109.1% | 27.6% |
| Beta vs S&P 500 | 1.17 | 0.84 |
| Max drawdown (3Y) | -93.0% | -24.7% |
| Market cap | $1.5B | $1.0B |
| P/E (trailing) | – | 14.7 |
| Dividend yield | 0.00% | 4.39% |
| Sector / category | US Listed | US Listed |
Year-by-year returns
| Year | FCEL | NBBK |
|---|---|---|
| 2022 | -46.5% | – |
| 2023 | -42.4% | – |
| 2024 | -81.2% | +34.3% |
| 2025 | -19.1% | +10.6% |
| 2026 | +164.3% | +13.9% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are FCEL and NBBK good diversifiers for each other?
By historical standards, yes. A correlation of -0.22 means the two rarely move for the same reasons.
FAQ
What is the correlation between FCEL and NBBK?
The FCEL/NBBK correlation stands at -0.22 on a 3-year window (1 year: -0.34, 5 years: n/a), computed from weekly returns as of 2026-08-27.
Is NBBK a good diversifier for FCEL?
By historical standards, yes. A correlation of -0.22 means the two rarely move for the same reasons.
What does a correlation of -0.22 mean?
A reading of -0.22 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/fcel-vs-nbbk.json
Drop this badge in a README or notebook; it updates with the data:
[](https://www.pairbook.io/pair/fcel-vs-nbbk/)
The core API is free. Terms and every endpoint in the API documentation.
Related comparisons
Hubs: FCEL correlations · NBBK correlations
