Marilyn Tavenner is about to make an unprecedented move: From head of Medicare, to the nation’s top lobbyist for private insurers — in just six months.

Four-hospital UCLA Health said Friday that cyber criminals hit part of its network that contains the records of an estimated 4.5 million people.

Without another pool of potential enrollees, the Affordable Care Act likely will face enrollment stagnation -- and that could threaten the country's steadily falling uninsured rate.

Marilyn B. Tavenner, the former Obama administration official in charge of the rollout of HealthCare.gov, was chosen on Wednesday to be the top lobbyist for the nation’s health insurance industry.

More than a dozen other states that expanded their Medicaid programs under the ACA also have seen enrollment surpass expectations.

San Francisco will begin offering subsidies to thousands of city residents who are struggling to purchase health insurance, Mayor Ed Lee announced Friday.