The proposed merger between health insurers Aetna and Humana would greatly reduce market competition for Medicare Advantage beneficiaries in the markets they serve, according to a new analysis by the Center for American Progress. “The Medicare Advantage market is currently highly concentrated,” the report notes. “CAP’s analysis of the overlap between Aetna and Humana in Medicare Advantage markets adds to other analyses that show that the proposed merger between the two companies would only exacerbate this trend, likely resulting in higher premiums for seniors and higher costs for the Medicare program.”