Medicare Advantage plans enrolled a record 9.8 million beneficiaries, more than one in five of the nation’s 44 million people on Medicare as of April 2008. That represents an increase of more than 800,000 beneficiaries in just four months, continuing a period of unprecedented growth for private plans in Medicare since 2003.

This issue brief, prepared for the Kaiser Family Foundation by Marsha Gold of Mathematica Policy Research, Inc., analyzes recent developments in the Medicare Advantage marketplace, including plan choices available to beneficiaries and enrollment trends by plan type and geography.

The brief also examines market share for the companies offering Medicare Advantage plans and the role Medicare Advantage plans play in providing employer-sponsored retiree health benefits.

 Issue Brief (.pdf)