Sens. Richard Blumenthal (D-CT), Al Franken (D-MN), Elizabeth Warren (D-MA), Sherrod Brown (D-OH), Edward Markey (D-MA), Dianne Feinstein (D-CA) and Mazie Hirono (D-HI) today urged the Department of Justice to challenge the proposed mergers of health insurance companies Aetna and Humana and Anthem and Cigna. “Highly concentrated markets rarely benefit consumers,” the senators said in a letter to Assistant Attorney General Renata Hesse. “[A]nd we believe that merging four of the five largest national health insurers will likely increase premium prices and health care costs to consumers and businesses, diminish competition and choice, and decrease access to quality health care.” The senators highlight the anticompetitive harm posed in the Medicare Advantage market from the Aetna-Humana merger, and the drastically reduced competition across Blue Cross Blue Shield and non-Blue markets that would result from the Anthem-Cigna merger. They also call into question the effectiveness of divestitures as a remedy for restoring competition, noting that “they have so clearly failed in the recent past.” The senators’ recommendations to DOJ echo and directly reference views expressed by the AHA in numerous communications on the issue.