Yahoo News: Aetna Inc.’s $37 billion deal to buy rival insurer Humana Inc. was blocked by a federal judge, thwarting one of two large mergers that would reshape the U.S. health-care landscape. Aetna said it was considering an appeal. The transaction would violate antitrust laws by reducing competition among insurers, U.S. District Judge John D. Bates in Washington ruled on Monday. With the deal defeated, Aetna owes Humana a $1 billion breakup fee under the terms of the merger agreement. Aetna countered that the Medicare market is much larger than the Justice Department claims because it includes both Medicare Advantage plans and original Medicare, providing more choice for seniors than the government portrayed. Competition on the exchanges isn’t an issue, they said, because Aetna withdrew from all 17 counties at issue in the government’s case.