Aetna has dropped its membership in America's Health Insurance Plans, the second major insurer to leave the trade group. UnitedHealth Group left AHIP last year.

The move comes amid consolidation and other changes roiling the industry following passage of the Affordable Care Act in 2010. Aetna's proposed acquisition of Humana is being scrutinized by regulators and opposed by some health care groups, including the American Medical Association. Two other AHIP members, Cigna and Anthem, are also seeking to merge.

Longtime CEO Karen Ignagni left AHIP last year to lead New York-based insurer EmblemHealth. Marilyn Tavenner became CEO in August. Tavenner had overseen writing many of the new rules implementing the health law as administrator of the Centers for Medicare and Medicaid Services.

AHIP reported revenue of $67 million in 2014, down from $71 million in 2012 and a whopping $185 million in 2010 when the health care law was being debated in Congress.

Statements from Aetna and AHIP were reported by multiple news organizations.

Aetna spokeswoman Cynthia Michener: "Aetna has decided not to renew our AHIP membership for 2016. We will continue to partner with groups that are working, as we are, toward expanding access to high-quality, affordable healthcare."

Tavenner: "AHIP's successful advocacy record speaks for itself. Our members depend on AHIP to advance their key priorities, to strengthen the public-private programs that provide coverage for millions of Americans, and to deliver solutions that improve access to high quality, affordable care for consumers."

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