Pacificare, HPA Sign Merger: PacifiCare Health Systems Inc. said it has reached a definitive agreement to acquire Health Plan of America, forming one of the largest health maintenance organizations in the state. The merger, first announced on Sept. 3., is now subject to regulatory approval. Financial terms were not disclosed by the companies, but analysts have valued the deal at between $90 million and $95 million. Health Plan, headquartered in Orange, has 125,000 members. Cypress based-PacifiCare has more than 700,000 members in five states. The merger will make PacifiCare the state’s second-largest HMO in terms of revenue, after Kaiser Permanente, the company said.