UnitedHealth Group Inc. said Wednesday that it has completed its $9 billion purchase of Cypress-based PacifiCare Health Systems Inc.

Minnetonka, Minn.-based UnitedHealth earlier this week won approvals for the deal from federal antitrust and California insurance regulators, including California Insurance Commissioner John Garamendi, who extracted concessions from the companies similar to those reached in last year’s acquisition of Thousand Oaks-based WellPoint Health Networks by Anthem Inc.

The companies agreed to U.S. Justice Department requirements that PacifiCare divest businesses in other states that overlap with UnitedHealth’s and change an agreement with a Blue Shield subsidiary in California.

Garamendi and the California Department of Managed Health Care required the companies to guarantee that California premiums would not increase to pay for the merger and that high-quality care would continue for PacifiCare’s members. The company also will make a total $250 million in investments and charitable contributions toward improving healthcare services in underserved communities.

Howard Phanstiel, PacifiCare’s chief executive officer, will become an executive vice president for UnitedHealth.

UnitedHealth is the No. 2 health insurer in the U.S., covering 53.8 million people nationwide through its own programs and those it manages through other firms. PacifiCare has 14.5 million members in its health and specialty plans.