A federal judge on Wednesday blocked a proposed $48 billion merger of Anthem and Cigna, derailing another effort by top health insurers to reshape the industry by combining.

The ruling, by Judge Amy Berman Jackson of the Federal District Court for the District of Columbia, came two weeks after another federal judge blocked a proposed $37 billion merger between Aetna and Humana on antitrust grounds.

Judge Jackson wrote in her order that she found the Justice Department’s arguments against the deal persuasive, and that putting Anthem and Cigna together would harm customers.

“The evidence has also shown that the merger is likely to result in higher prices, and that it will have other anticompetitive effects,” the judge wrote. “It will eliminate the two firms’ vigorous competition against each other for national accounts, reduce the number of national carriers available to respond to solicitations in the future, and diminish the prospects for innovation in the market.”