The country’s largest physician lobbying group has come out against a proposed merger between Aetna and CVS.

The American Medical Association (AMA) announced its formal opposition during a hearing Tuesday before the California Department of Insurance.

AMA said it is concerned the proposed merger will result in reduced competition in the insurance market.

ADVERTISEMENT

“The AMA has come to the conclusion that this merger would likely substantially lessen competition in many health care markets, to the detriment of patients,” AMA President Barbara McAneny said in prepared testimony released by the group.

If approved, the $69 billion merger of the nation’s largest pharmacy and third-largest health insurer could have major implications for the industry. It is expected to close in the second half of this year, pending regulatory approval by the Department of Justice.

The AMA said it will release a memo later this month giving more specific analysis of its opposition.

But in a statement, McAneny highlighted some initial areas of concern, including an anticipated increase in drug spending and out-of-pocket costs for patients, as well as higher insurance premiums and a reduction in the quality of insurance.

CVS and Aetna executives have said the deal will decrease costs for consumers.

“The combined company will be well-positioned to reshape the consumer health care experience, putting people at the center of health care delivery to ensure they have access to high-quality, more affordable care where they are, when they need it," CVS Health President and CEO Larry Merlo said in a statement in March, when the merger was approved by shareholders.