Federal regulators approve pharmacy benefit manager merger despite congressional objections

"The acquisition of Medco by Express Scripts will likely not change these dynamics: The merging parties are not particularly close competitors, the market today is not conducive to coordinated interaction, and there is little risk of the merged company exercising monopsony power," the commission said in a statement. "Under these circumstances, we lack a reason to believe that a violation of Section 7 of the Clayton Act has occurred or is likely to occur by means of Express Scripts' acquisition of Medco."

In her dissenting statement, Commissioner Julie Brill called the merger an industry "game changer" that creates a "merger to duopoly" between the new entity and CVS Caremark, "with few efficiencies and high entry barriers — something no court has ever approved."

Anticipating a prompt FTC decision, drug retailers last week filed suit and asked a federal court for a temporary restraining order blocking the merger until the court can issue a ruling.

After closing on the Medco acquisition, both Express Scripts Inc. and Medco Health Solutions Inc. are wholly owned subsidiaries of Express Scripts Holding Co.