A new report from the consulting firm Oliver Wyman finds that "more than two-thirds of the U.S. population now live in localities served by
accountable care organizations (ACOs) and more than 40 percent live in areas served by two or more."

Read the research brief online at: http://www.oliverwyman.com/content/dam/oliver-wyman/global/en/files/insights/health-life-sciences/2014/April/NYC-MKT08001-034%20(4).pdf

Interesting quote on page 2:

"Current enrollments are problematic, Gandhi explains, because most ACOs are
currently at an early stage of development, offering care that differs very little
from traditional healthcare providers. But the fact that they are reimbursed
differently than traditional fee-for-service providers means that they can begin
to profit from eliminating unnecessary services and replacing treatment with
prevention—something fee-for-service providers cannot do."