A federal judge ruled that the $37 billion merger between Aetna (CS) and Humana (CS) should not be allowed to go through on antitrust grounds, siding with the Justice Department, which had been seeking to block the deal. The deal is one of two mega-mergers proposed by the nation’s largest health insurers; both were challenged by the Obama administration. Another federal judge is expected to rule soon on the case involving Anthem and Cigna, the larger of the two deals, at $48 billion. Monday’s decision adds to the uncertainty facing the industry, with President Trump and the Republican-controlled Congress having vowed to repeal the Affordable Care Act and replace it with something else, the details of which are unknown. While the judge found that a merger of Aetna and Humana would not be in the interest of its consumers, companies are likely to remain interested in future combinations. Insurers view mergers as a way to gain greater clout in negotiations with hospitals and doctors, according to a report in the New York Times. An Aetna spokesman said the company was reviewing the opinion and “is giving serious consideration to an appeal.” Humana did not respond to an email seeking comment. If the deal falls apart, Aetna would have to pay Humana $1 billion, according to the terms of the merger agreement. To read more, visit www.nytimes.com/2017/01/23/business/dealbook/aetna-humana-deal-blocked.html.