U.S. District Judge John D. Bates has issued an opinion blocking the proposed mega-merger of insurance giants Aetna and Humana. He cited antitrust concerns, noting that efficiencies gained through such a merger wouldn't be sufficient to offset the anticompetitive effects for consumers.

The U.S. Justice Department sued to stop the merger in July amid concerns over the impact of reduced competition in the Medicare Advantage market and in some ACA exchanges. A spokesperson for Aetna said the company is currently reviewing options and considering an appeal. The current merger agreement is set to expire on Feb. 15.

In response to the decision, American Hospital Association President and CEO Rick Pollack released the following statement:

"Today's decision rightly puts the needs of patients first in ensuring they have access to healthcare coverage that is affordable. The Court's decision to halt the Aetna-Humana deal promises more than 2.7 million Medicare Advantage (MA) patients the benefits of greater competition, including lower out-of-pocket costs and more access to high-quality care. Humana is the second-largest Medicare Advantage insurer and Aetna the fourth with plans in more than 1,000 markets. If this deal had been allowed to proceed, it would have eliminated current competition as well as the possibility of future competition. Such consolidation would no doubt result in higher premiums and less choice. Competition in the insurance sector is essential to keeping Medicare Advantage healthy, growing and affordable for seniors; with today's decision the court affirmed the importance of those benefits."