ACIW vs HSTM: Correlation
How closely do ACI Worldwide, Inc. (ACIW) and HealthStream, Inc. (HSTM) trade together? Their weekly returns over three years give a correlation of 0.50, which is moderate.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are ACIW and HSTM?
Over the past 3 years, ACIW and HSTM moved with a correlation of 0.50, which is moderate. The relationship has been stable: the 1-year correlation (0.51) sits close to the 3-year figure. Over 5 years the correlation is 0.44, and the annualized covariance of weekly returns is 483.5 %².
By 3-year correlation, HSTM places #8 of the 20 assets tracked against ACIW. Over the last 12 months ACIW came out ahead by 9.6 percentage points (+11.8% against +2.2%).
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.
ACIW vs HSTM: side by side
| ACIW (ACI Worldwide, Inc.) | HSTM (HealthStream, Inc.) | |
|---|---|---|
| 1-year return | +11.8% | +2.2% |
| 5-year return | +69.0% | -1.6% |
| Volatility (ann.) | 35.3% | 27.4% |
| Beta vs S&P 500 | 1.07 | 0.54 |
| Max drawdown (3Y) | -35.0% | -41.4% |
| Market cap | $5.5B | $0.8B |
| P/E (trailing) | 24.3 | 40.0 |
| Dividend yield | 0.00% | 0.46% |
| Sector / category | US Listed | US Listed |
Year-by-year returns
| Year | ACIW | HSTM |
|---|---|---|
| 2022 | -33.7% | -5.8% |
| 2023 | +33.0% | +9.3% |
| 2024 | +69.6% | +18.1% |
| 2025 | -7.9% | -27.1% |
| 2026 | +13.4% | +25.5% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are ACIW and HSTM good diversifiers for each other?
Only partially. A correlation of 0.50 means ACIW and HSTM 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 ACIW and HSTM?
As of 2026-08-27, the correlation of weekly returns between ACIW and HSTM is 0.50 over 3 years, 0.51 over 1 year and 0.44 over 5 years.
Is HSTM a good diversifier for ACIW?
Only partially. A correlation of 0.50 means ACIW and HSTM 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?
On the −1 to +1 scale, 0.50 describes how much the two returns move together: +1 is lockstep, 0 is independence, negative values mean opposite directions. It says nothing about which performed better.
Use this data
$ curl https://www.pairbook.io/api/v1/pairs/aciw-vs-hstm.json
Drop this badge in a README or notebook; it updates with the data:
[](https://www.pairbook.io/pair/aciw-vs-hstm/)
No key needed, free to use. Full endpoint list in the API documentation.
Related comparisons
Hubs: ACIW correlations · HSTM correlations
