Medicare Advantage beneficiaries enroll in only a few plans

Nationwide, 283 insurers have some form of contract to sponsor a Medicare Advantage or other prepaid group plan. MA plans are set up geographically. That means that 99 percent of beneficiaries have a choice of plans to choose from, according to report by the Kaiser Family Foundation called Strategies for Simplifying the Medicare Advantage Market.

Yet while many insurers participate in the individual MA market, national enrollment tends to be concentrated with a small number of insurers. One in three individual enrollees is in a plan sponsored by either UnitedHealthcare (18 percent) or Humana (15 percent). These and nine other insurers account for more than half of all enrollment. Another 16 percent of enrollees are involved with insurers that are independently owned by a Blue Cross & Blue Shield affiliate.

MA enrollment by insurer or affiliate, 2009

Note: Excludes group and special needs plans. Only enrollees in authorized MA plans are included.

Source: The Henry J. Kaiser Family Foundation, Strategies for Simplifying the Medicare Advantage Market, July 2009