FSTR vs INSP: Correlation
Measured on weekly returns over the past three years, L.B. Foster Company (FSTR) and Inspire Medical Systems, Inc. (INSP) carry a correlation of -0.23, a negative link.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are FSTR and INSP?
Across a 3-year window, the weekly returns of FSTR and INSP correlate at -0.23, negative, meaning they tend to move in opposite directions. Recent behaviour matches the longer record: -0.31 over 1 year against -0.23 over 3. Stretching to 5 years gives -0.13, with an annualized covariance of -731.8 %².
Within FSTR's tracked universe of 16 assets, INSP comes in at #11 by 3-year correlation. The last year tells two different stories: FSTR led by 76.9 percentage points, +42.8% for FSTR against -34.1% for INSP.
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.
FSTR vs INSP: side by side
| FSTR (L.B. Foster Company) | INSP (Inspire Medical Systems, Inc.) | |
|---|---|---|
| 1-year return | +42.8% | -34.1% |
| 5-year return | +119.1% | -72.6% |
| Volatility (ann.) | 46.4% | 67.2% |
| Beta vs S&P 500 | 1.23 | 0.77 |
| Max drawdown (3Y) | -45.9% | -84.1% |
| Market cap | $0.4B | $1.8B |
| P/E (trailing) | 35.4 | 13.6 |
| Dividend yield | 0.00% | 0.00% |
| Sector / category | US Listed | US Listed |
Year-by-year returns
| Year | FSTR | INSP |
|---|---|---|
| 2022 | -29.6% | +9.5% |
| 2023 | +127.2% | -19.2% |
| 2024 | +22.3% | -8.9% |
| 2025 | +0.2% | -50.2% |
| 2026 | +40.4% | -34.1% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are FSTR and INSP good diversifiers for each other?
Yes. With a correlation of -0.23, FSTR and INSP have moved largely independently, which makes them a genuinely diversifying pair by historical standards.
FAQ
What is the correlation between FSTR and INSP?
As of 2026-08-27, the correlation of weekly returns between FSTR and INSP is -0.23 over 3 years, -0.31 over 1 year and -0.13 over 5 years.
Is INSP a good diversifier for FSTR?
Yes. With a correlation of -0.23, FSTR and INSP have moved largely independently, which makes them a genuinely diversifying pair by historical standards.
What does a correlation of -0.23 mean?
A reading of -0.23 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/fstr-vs-insp.json
Markdown for the live badge, attribution link included:
[](https://www.pairbook.io/pair/fstr-vs-insp/)
Free with attribution; caching and terms are described in the API documentation.
Related comparisons
Hubs: FSTR correlations · INSP correlations
