BLDP vs STK: Correlation
Measured on weekly returns over the past three years, Ballard Power Systems, Inc. (BLDP) and Columbia Seligman Premium Technology Growth Fund Inc (STK) carry a correlation of 0.50, a moderate link.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are BLDP and STK?
On 3 years of weekly data the BLDP/STK correlation comes out at 0.50, moderate. Little has changed lately, as the 1-year reading of 0.57 lands near the 3-year figure. The 5-year figure is 0.54, and annualized covariance runs at 871.6 %².
Within BLDP's tracked universe of 23 assets, STK comes in at #4 by 3-year correlation. The last year tells two different stories: STK led by 61.0 percentage points, +15.8% for BLDP against +76.8% for STK. One caveat on sizing: BLDP is 2.5 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.
BLDP vs STK: side by side
| BLDP (Ballard Power Systems, Inc.) | STK (Columbia Seligman Premium Technology Growth Fund Inc) | |
|---|---|---|
| 1-year return | +15.8% | +76.8% |
| 5-year return | -85.8% | +153.2% |
| Volatility (ann.) | 66.3% | 26.4% |
| Beta vs S&P 500 | 1.62 | 1.51 |
| Max drawdown (3Y) | -76.4% | -26.6% |
| Market cap | $0.7B | – |
| P/E (trailing) | – | 5.9 |
| Dividend yield | 0.00% | 0.00% |
| Sector / category | US Listed | US Listed |
Year-by-year returns
| Year | BLDP | STK |
|---|---|---|
| 2022 | -61.9% | -30.4% |
| 2023 | -22.8% | +49.2% |
| 2024 | -55.1% | +17.7% |
| 2025 | +53.0% | +24.9% |
| 2026 | -7.9% | +47.2% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are BLDP and STK good diversifiers for each other?
Only partially. A correlation of 0.50 means BLDP and STK share most of their swings. Pairing them dampens volatility somewhat, but it will not protect against a common drawdown.
FAQ
What is the correlation between BLDP and STK?
Using weekly returns as of 2026-08-27: 0.50 over 3 years, with 0.57 over the last year and 0.54 over 5 years.
Is STK a good diversifier for BLDP?
Only partially. A correlation of 0.50 means BLDP and STK share most of their swings. Pairing them dampens volatility somewhat, but it will not protect against a common drawdown.
What does a correlation of 0.50 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/bldp-vs-stk.json
Embed this badge (it refreshes with the data), with attribution:
[](https://www.pairbook.io/pair/bldp-vs-stk/)
No key needed, free to use. Full endpoint list in the API documentation.
Related comparisons
Hubs: BLDP correlations · STK correlations
