CI vs MRK: Correlation
How closely do Cigna (CI) and Merck & Co. (MRK) trade together? Their weekly returns over three years give a correlation of 0.34, which is moderate.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are CI and MRK?
Over the past 3 years, CI and MRK moved with a correlation of 0.34, which is moderate. Little has changed lately, as the 1-year reading of 0.38 lands near the 3-year figure. Over 5 years the correlation is 0.35, and the annualized covariance of weekly returns is 255.5 %².
By 3-year correlation, MRK places #17 of the 30 assets tracked against CI. Correlation aside, the last 12 months split them widely, with MRK ahead by 89.2 points (-5.4% versus +83.8%). Across three years, the rolling one-year figure varied moderately, from 0.16 to 0.52.
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.
CI vs MRK: side by side
| CI (Cigna) | MRK (Merck & Co.) | |
|---|---|---|
| 1-year return | -5.4% | +83.8% |
| 5-year return | +46.7% | +128.5% |
| Volatility (ann.) | 26.7% | 27.9% |
| Beta vs S&P 500 | 0.22 | 0.28 |
| Max drawdown (3Y) | -32.1% | -43.4% |
| Market cap | $73.4B | $368.9B |
| P/E (trailing) | 11.6 | 121.6 |
| Dividend yield | 2.19% | 2.17% |
| Sector / category | Health Care | Health Care |
Year-by-year returns
| Year | CI | MRK |
|---|---|---|
| 2022 | +46.7% | +49.4% |
| 2023 | -8.0% | +1.0% |
| 2024 | -6.3% | -6.3% |
| 2025 | +1.7% | +9.8% |
| 2026 | +2.0% | +44.1% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are CI and MRK good diversifiers for each other?
A fair diversifier. At 0.34, enough of each asset's movement is its own that the pair has smoothed outcomes historically.
FAQ
What is the correlation between CI and MRK?
Using weekly returns as of 2026-08-27: 0.34 over 3 years, with 0.38 over the last year and 0.35 over 5 years.
Is MRK a good diversifier for CI?
A fair diversifier. At 0.34, enough of each asset's movement is its own that the pair has smoothed outcomes historically.
What does a correlation of 0.34 mean?
On the −1 to +1 scale, 0.34 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/ci-vs-mrk.json
Drop this badge in a README or notebook; it updates with the data:
[](https://www.pairbook.io/pair/ci-vs-mrk/)
No key needed, free to use. Full endpoint list in the API documentation.
Related comparisons
Hubs: CI correlations · MRK correlations
