Medicare enrollees tend to flock to one to three Medicare Advantage carriers in each market.
Researchers at the Henry J. Kaiser Family Foundation, Menlo Park, Calif., have published that conclusion in a report based on analysis of federal Medicare Advantage enrollment data.
In 14 states and the District of Columbia, one carrier enrolls more than half the Medicare Advantage enrollees, researchers say.
In most other states, two or three carriers cover a majority of the enrollees.