Health insurers' outlook continues to be negative as the sector faces new regulations, heightened political pressure and a weak economy, which are expected to squeeze earnings, one major ratings agency said.

Moody's Investors Service said in a report that insurance provisions of the Patient Protection and Affordable Care Act that go into effect this year could limit insurers' income. Analysts described 2011 “as a transition year” for insurers as companies grapple with new medical-loss ratio regulations, which require 85% of large group premiums and 80% of small group and individual premiums to be spent on patient care.

Flat Medicare Advantage reimbursement levels for 2011, to be followed by cuts next year, could squeeze insurers' margins, the report said. Insurers have moved to diversify to increase revenue and income not affected by changes under the reform law, analysts said. The sector also faces greater oversight and political pressure regarding insurers' premium increases.

Insurers also face threats to enrollment from the economy, according to the report. The weak job market and possible further layoffs in the public sector this year could leave more households without employment, the source of health insurance for many, the report said. Struggling employers and households may not be willing or able to pay for care even as providers seek pay increases to increase revenue.