Standard & Poor's NetAdvantage Industry Surveys - Healthcare: Managed Care and Healthcare: Facilities. - Information Desk1 - This is an excellent overview of recent changes and the current state of the industry. NetAdvantage provides the latest 5 years. Horn Library has older paper copies in the Periodical Stacks and the most current at Library Information Desk 1.
Massachusetts Hospitals Association - Particularly interesting are Collaboration Activity, Publications (including HMO Enrollment Trends), Reports, In the News archives, and Links to Other Sources. Some reports are for members only.
Factiva - first use the Revise Publications feature to search only Massachusetts papers. For your search strategy you might want to try entering (boston or massachusetts) and atleast15 hmo$ or something similar. Vary the number to narrow or expand results. Or focus on a particular HMO or issue.