Enrollment in private health insurance plans in the individual (coverage sold directly to individuals), small group (coverage offered by small employers), and large group (coverage offered by large employers) markets has historically been highly concentrated among a small number of issuers. GAO found that this pattern continued in 2017 and 2018. Overall individual and small group markets have become more concentrated in recent years. The national median market share of the top three issuers increased by approximately 8 and 5 percentage points, respectively, from 2015 through 2018. With these increases, the median concentration was at least 94 percent in both markets in 2018.
Read the full article: GAO: Private Health Insurance Markets Remained Concentrated through 2018, with Increases in the Individual and Small Group Markets //
Source: https://www.gao.gov/products/GAO-21-34#summary