Federal judge blocks Aetna-Humana health insurance megamerger http://wpo.st/OegT2 A federal judge has prohibited the merger of two health insurance giants, Aetna and Humana, upholding the Justice Department's decision that the $37 billion deal would hurt competition. "The Court is unpersuaded that the efficiencies generated by the merger will be sufficient to mitigate the anticompetitive effects for consumers in the challenged markets," U.S. District Judge John D. Bates wrote in his 158-page opinion. In July, the Justice Department sued to block the merger, arguing that it would reduce competition in the Medicare Advantage market and in the exchanges set up under the Affordable Care Act.