A federal judge on Wednesday blocked the proposed merger between health-insurance giants Anthem and Cigna. The $54 billion agreement, according to Judge Amy Berman Jackson, would likely have led to price increases due to less competition. Along with a proposed merger between Aetna and Humana that was struck down last month, the Anthem-Cigna deal would have reduced the number of national insurers from five to three. The Justice Department filed a lawsuit last July in an effort to block the merger.