Medicare Advantage: National Carriers Expand Market Share While Regional Carriers Without Affiliation Decline, 2012-23.

This study examined the evolving landscape of insurer competition in the Medicare Advantage (MA) program from both national and local perspectives. Data from the Centers for Medicare and Medicaid Services revealed that the MA market has become more concentrated. National carriers expanded their national market share significantly from 2012 to 2023, whereas the collective market share of regional carriers without affiliation to Blue Cross and Blue Shield organizations declined because of acquisitions. For example, the combined national market share of national carriers increased from 46 percent in 2012 to 66 percent in 2023, while the combined national market share of non-Blue regional carriers decreased from 25 percent to 6 percent. Conversely, concentration in local markets has declined but remains highly concentrated, and evidence suggests that further declines may be unlikely. Specifically, declines in local market concentration have been limited to markets with low MA penetration. Once MA penetration exceeds 20 percent, further MA growth is not associated with further drops in concentration, on average. Thus, policy makers should be aware that MA program reforms that assume MA markets are competitive are unlikely to achieve program goals without ensuring the competitiveness of those markets.